feat(vendor): support using an existing import map (#14836)

13 files changed, 1171 insertions, 249 deletions

diff --git a/cli/Cargo.toml b/cli/Cargo.toml
index 61063fd0b..56cae2090 100644
--- a/cli/Cargo.toml
+++ b/cli/Cargo.toml
@@ -71,7 +71,7 @@ env_logger = "=0.9.0"
 eszip = "=0.20.0"
 fancy-regex = "=0.9.0"
 http = "=0.2.6"
-import_map = "=0.9.0"
+import_map = "=0.11.0"
 indexmap = "1.8.1"
 jsonc-parser = { version = "=0.19.0", features = ["serde"] }
 libc = "=0.2.126"
diff --git a/cli/config_file.rs b/cli/config_file.rs
index 3644bb7c1..4b2596ba2 100644
--- a/cli/config_file.rs
+++ b/cli/config_file.rs
@@ -11,6 +11,7 @@ use deno_core::anyhow::bail;
 use deno_core::anyhow::Context;
 use deno_core::error::custom_error;
 use deno_core::error::AnyError;
+use deno_core::normalize_path;
 use deno_core::serde::Deserialize;
 use deno_core::serde::Serialize;
 use deno_core::serde::Serializer;
@@ -262,12 +263,12 @@ pub fn resolve_import_map_specifier(
           // file into a file path if possible and join the import map path to
           // the file path.
           if let Ok(config_file_path) = config_file.specifier.to_file_path() {
-            let import_map_file_path = config_file_path
+            let import_map_file_path = normalize_path(config_file_path
               .parent()
               .ok_or_else(|| {
                 anyhow!("Bad config file specifier: {}", config_file.specifier)
               })?
-              .join(&import_map_path);
+              .join(&import_map_path));
             ModuleSpecifier::from_file_path(import_map_file_path).unwrap()
           // otherwise if the config file is remote, we have no choice but to
           // use "import resolution" with the config file as the base.
diff --git a/cli/fs_util.rs b/cli/fs_util.rs
index fe0ef8857..578a2ec37 100644
--- a/cli/fs_util.rs
+++ b/cli/fs_util.rs
@@ -5,6 +5,7 @@ use deno_core::error::{uri_error, AnyError};
 pub use deno_core::normalize_path;
 use deno_core::ModuleSpecifier;
 use deno_runtime::deno_crypto::rand;
+use std::borrow::Cow;
 use std::env::current_dir;
 use std::fs::OpenOptions;
 use std::io::{Error, Write};
@@ -362,6 +363,44 @@ pub fn specifier_parent(specifier: &ModuleSpecifier) -> ModuleSpecifier {
   specifier
 }
 
+/// `from.make_relative(to)` but with fixes.
+pub fn relative_specifier(
+  from: &ModuleSpecifier,
+  to: &ModuleSpecifier,
+) -> Option<String> {
+  let is_dir = to.path().ends_with('/');
+
+  if is_dir && from == to {
+    return Some("./".to_string());
+  }
+
+  // workaround using parent directory until https://github.com/servo/rust-url/pull/754 is merged
+  let from = if !from.path().ends_with('/') {
+    if let Some(end_slash) = from.path().rfind('/') {
+      let mut new_from = from.clone();
+      new_from.set_path(&from.path()[..end_slash + 1]);
+      Cow::Owned(new_from)
+    } else {
+      Cow::Borrowed(from)
+    }
+  } else {
+    Cow::Borrowed(from)
+  };
+
+  // workaround for url crate not adding a trailing slash for a directory
+  // it seems to be fixed once a version greater than 2.2.2 is released
+  let mut text = from.make_relative(to)?;
+  if is_dir && !text.ends_with('/') && to.query().is_none() {
+    text.push('/');
+  }
+
+  Some(if text.starts_with("../") || text.starts_with("./") {
+    text
+  } else {
+    format!("./{}", text)
+  })
+}
+
 /// This function checks if input path has trailing slash or not. If input path
 /// has trailing slash it will return true else it will return false.
 pub fn path_has_trailing_slash(path: &Path) -> bool {
@@ -749,6 +788,39 @@ mod tests {
   }
 
   #[test]
+  fn test_relative_specifier() {
+    run_test("file:///from", "file:///to", Some("./to"));
+    run_test("file:///from", "file:///from/other", Some("./from/other"));
+    run_test("file:///from", "file:///from/other/", Some("./from/other/"));
+    run_test("file:///from", "file:///other/from", Some("./other/from"));
+    run_test("file:///from/", "file:///other/from", Some("../other/from"));
+    run_test("file:///from", "file:///other/from/", Some("./other/from/"));
+    run_test(
+      "file:///from",
+      "file:///to/other.txt",
+      Some("./to/other.txt"),
+    );
+    run_test(
+      "file:///from/test",
+      "file:///to/other.txt",
+      Some("../to/other.txt"),
+    );
+    run_test(
+      "file:///from/other.txt",
+      "file:///to/other.txt",
+      Some("../to/other.txt"),
+    );
+
+    fn run_test(from: &str, to: &str, expected: Option<&str>) {
+      let result = relative_specifier(
+        &ModuleSpecifier::parse(from).unwrap(),
+        &ModuleSpecifier::parse(to).unwrap(),
+      );
+      assert_eq!(result.as_deref(), expected);
+    }
+  }
+
+  #[test]
   fn test_path_has_trailing_slash() {
     #[cfg(not(windows))]
     {
diff --git a/cli/lsp/completions.rs b/cli/lsp/completions.rs
index b3e338faf..a41e26bf5 100644
--- a/cli/lsp/completions.rs
+++ b/cli/lsp/completions.rs
@@ -208,8 +208,8 @@ fn get_base_import_map_completions(
   import_map: &ImportMap,
 ) -> Vec<lsp::CompletionItem> {
   import_map
-    .imports_keys()
-    .iter()
+    .imports()
+    .keys()
     .map(|key| {
       // for some strange reason, keys that start with `/` get stored in the
       // import map as `file:///`, and so when we pull the keys out, we need to
@@ -253,7 +253,7 @@ fn get_import_map_completions(
   if !text.is_empty() {
     if let Some(import_map) = maybe_import_map {
       let mut items = Vec::new();
-      for key in import_map.imports_keys() {
+      for key in import_map.imports().keys() {
         // for some reason, the import_map stores keys that begin with `/` as
         // `file:///` in its index, so we have to reverse that here
         let key = if key.starts_with("file://") {
diff --git a/cli/proc_state.rs b/cli/proc_state.rs
index d90b3f952..2c454c0ee 100644
--- a/cli/proc_state.rs
+++ b/cli/proc_state.rs
@@ -51,7 +51,6 @@ use deno_runtime::deno_tls::rustls::RootCertStore;
 use deno_runtime::deno_web::BlobStore;
 use deno_runtime::inspector_server::InspectorServer;
 use deno_runtime::permissions::Permissions;
-use import_map::parse_from_json;
 use import_map::ImportMap;
 use log::warn;
 use std::collections::HashSet;
@@ -737,7 +736,12 @@ pub fn import_map_from_text(
   specifier: &Url,
   json_text: &str,
 ) -> Result<ImportMap, AnyError> {
-  let result = parse_from_json(specifier, json_text)?;
+  debug_assert!(
+    !specifier.as_str().contains("../"),
+    "Import map specifier incorrectly contained ../: {}",
+    specifier.as_str()
+  );
+  let result = import_map::parse_from_json(specifier, json_text)?;
   if !result.diagnostics.is_empty() {
     warn!(
       "Import map diagnostics:\n{}",
@@ -747,7 +751,7 @@ pub fn import_map_from_text(
         .map(|d| format!("  - {}", d))
         .collect::<Vec<_>>()
         .join("\n")
-    )
+    );
   }
   Ok(result.import_map)
 }
diff --git a/cli/resolver.rs b/cli/resolver.rs
index af0cc773c..30149278c 100644
--- a/cli/resolver.rs
+++ b/cli/resolver.rs
@@ -30,7 +30,7 @@ impl Resolver for ImportMapResolver {
     referrer: &ModuleSpecifier,
   ) -> ResolveResponse {
     match self.0.resolve(specifier, referrer) {
-      Ok(specifier) => ResolveResponse::Specifier(specifier),
+      Ok(resolved_specifier) => ResolveResponse::Specifier(resolved_specifier),
       Err(err) => ResolveResponse::Err(err.into()),
     }
   }
diff --git a/cli/tests/integration/vendor_tests.rs b/cli/tests/integration/vendor_tests.rs
index 5737f0365..7c106c79b 100644
--- a/cli/tests/integration/vendor_tests.rs
+++ b/cli/tests/integration/vendor_tests.rs
@@ -3,20 +3,19 @@
 use deno_core::serde_json;
 use deno_core::serde_json::json;
 use pretty_assertions::assert_eq;
-use std::fs;
 use std::path::PathBuf;
 use std::process::Stdio;
 use test_util as util;
 use test_util::TempDir;
 use util::http_server;
+use util::new_deno_dir;
 
 #[test]
 fn output_dir_exists() {
   let t = TempDir::new();
-  let vendor_dir = t.path().join("vendor");
-  fs::write(t.path().join("mod.ts"), "").unwrap();
-  fs::create_dir_all(&vendor_dir).unwrap();
-  fs::write(vendor_dir.join("mod.ts"), "").unwrap();
+  t.write("mod.ts", "");
+  t.create_dir_all("vendor");
+  t.write("vendor/mod.ts", "");
 
   let deno = util::deno_cmd()
     .current_dir(t.path())
@@ -76,15 +75,12 @@ fn output_dir_exists() {
 #[test]
 fn import_map_output_dir() {
   let t = TempDir::new();
-  let vendor_dir = t.path().join("vendor");
-  fs::write(t.path().join("mod.ts"), "").unwrap();
-  fs::create_dir_all(&vendor_dir).unwrap();
-  let import_map_path = vendor_dir.join("import_map.json");
-  fs::write(
-    &import_map_path,
+  t.write("mod.ts", "");
+  t.create_dir_all("vendor");
+  t.write(
+    "vendor/import_map.json",
     "{ \"imports\": { \"https://localhost/\": \"./localhost/\" }}",
-  )
-  .unwrap();
+  );
 
   let deno = util::deno_cmd()
     .current_dir(t.path())
@@ -92,7 +88,7 @@ fn import_map_output_dir() {
     .arg("vendor")
     .arg("--force")
     .arg("--import-map")
-    .arg(import_map_path)
+    .arg("vendor/import_map.json")
     .arg("mod.ts")
     .stdout(Stdio::piped())
     .stderr(Stdio::piped())
@@ -101,7 +97,14 @@ fn import_map_output_dir() {
   let output = deno.wait_with_output().unwrap();
   assert_eq!(
     String::from_utf8_lossy(&output.stderr).trim(),
-    "error: Using an import map found in the output directory is not supported.",
+    format!(
+      concat!(
+        "error: Specifying an import map file ({}) in the deno vendor ",
+        "output directory is not supported. Please specify no import ",
+        "map or one located outside this directory.",
+      ),
+      PathBuf::from("vendor").join("import_map.json").display(),
+    ),
   );
   assert!(!output.status.success());
 }
@@ -111,10 +114,10 @@ fn standard_test() {
   let _server = http_server();
   let t = TempDir::new();
   let vendor_dir = t.path().join("vendor2");
-  fs::write(
-    t.path().join("my_app.ts"),
+  t.write(
+    "my_app.ts",
     "import {Logger} from 'http://localhost:4545/vendor/query_reexport.ts?testing'; new Logger().log('outputted');",
-  ).unwrap();
+  );
 
   let deno = util::deno_cmd()
     .current_dir(t.path())
@@ -136,7 +139,7 @@ fn standard_test() {
         "Download http://localhost:4545/vendor/logger.ts?test\n",
         "{}",
       ),
-      success_text("2 modules", "vendor2", "my_app.ts"),
+      success_text("2 modules", "vendor2", true),
     )
   );
   assert_eq!(String::from_utf8_lossy(&output.stdout).trim(), "");
@@ -144,16 +147,14 @@ fn standard_test() {
 
   assert!(vendor_dir.exists());
   assert!(!t.path().join("vendor").exists());
-  let import_map: serde_json::Value = serde_json::from_str(
-    &fs::read_to_string(vendor_dir.join("import_map.json")).unwrap(),
-  )
-  .unwrap();
+  let import_map: serde_json::Value =
+    serde_json::from_str(&t.read_to_string("vendor2/import_map.json")).unwrap();
   assert_eq!(
     import_map,
     json!({
       "imports": {
-        "http://localhost:4545/": "./localhost_4545/",
         "http://localhost:4545/vendor/query_reexport.ts?testing": "./localhost_4545/vendor/query_reexport.ts",
+        "http://localhost:4545/": "./localhost_4545/",
       },
       "scopes": {
         "./localhost_4545/": {
@@ -169,7 +170,8 @@ fn standard_test() {
     .env("NO_COLOR", "1")
     .arg("run")
     .arg("--no-remote")
-    .arg("--no-check")
+    .arg("--check")
+    .arg("--quiet")
     .arg("--import-map")
     .arg("vendor2/import_map.json")
     .arg("my_app.ts")
@@ -207,7 +209,7 @@ fn remote_module_test() {
         "Download http://localhost:4545/vendor/logger.ts?test\n",
         "{}",
       ),
-      success_text("2 modules", "vendor/", "main.ts"),
+      success_text("2 modules", "vendor/", true),
     )
   );
   assert_eq!(String::from_utf8_lossy(&output.stdout).trim(), "");
@@ -217,10 +219,8 @@ fn remote_module_test() {
     .join("localhost_4545/vendor/query_reexport.ts")
     .exists());
   assert!(vendor_dir.join("localhost_4545/vendor/logger.ts").exists());
-  let import_map: serde_json::Value = serde_json::from_str(
-    &fs::read_to_string(vendor_dir.join("import_map.json")).unwrap(),
-  )
-  .unwrap();
+  let import_map: serde_json::Value =
+    serde_json::from_str(&t.read_to_string("vendor/import_map.json")).unwrap();
   assert_eq!(
     import_map,
     json!({
@@ -229,7 +229,7 @@ fn remote_module_test() {
       },
       "scopes": {
         "./localhost_4545/": {
-          "./localhost_4545/vendor/logger.ts?test": "./localhost_4545/vendor/logger.ts"
+          "./localhost_4545/vendor/logger.ts?test": "./localhost_4545/vendor/logger.ts",
         }
       }
     }),
@@ -237,49 +237,155 @@ fn remote_module_test() {
 }
 
 #[test]
-fn existing_import_map() {
+fn existing_import_map_no_remote() {
   let _server = http_server();
   let t = TempDir::new();
-  let vendor_dir = t.path().join("vendor");
-  fs::write(
-    t.path().join("mod.ts"),
+  t.write(
+    "mod.ts",
     "import {Logger} from 'http://localhost:4545/vendor/logger.ts';",
-  )
-  .unwrap();
-  fs::write(
-    t.path().join("imports.json"),
-    r#"{ "imports": { "http://localhost:4545/vendor/": "./logger/" } }"#,
-  )
-  .unwrap();
-  fs::create_dir(t.path().join("logger")).unwrap();
-  fs::write(t.path().join("logger/logger.ts"), "export class Logger {}")
+  );
+  let import_map_filename = "imports2.json";
+  let import_map_text =
+    r#"{ "imports": { "http://localhost:4545/vendor/": "./logger/" } }"#;
+  t.write(import_map_filename, &import_map_text);
+  t.create_dir_all("logger");
+  t.write("logger/logger.ts", "export class Logger {}");
+
+  let deno = util::deno_cmd()
+    .current_dir(t.path())
+    .env("NO_COLOR", "1")
+    .arg("vendor")
+    .arg("mod.ts")
+    .arg("--import-map")
+    .arg(import_map_filename)
+    .stderr(Stdio::piped())
+    .spawn()
     .unwrap();
+  let output = deno.wait_with_output().unwrap();
+  assert_eq!(
+    String::from_utf8_lossy(&output.stderr).trim(),
+    success_text("0 modules", "vendor/", false)
+  );
+  assert!(output.status.success());
+  // it should not have found any remote dependencies because
+  // the provided import map mapped it to a local directory
+  assert_eq!(t.read_to_string(import_map_filename), import_map_text);
+}
 
-  let status = util::deno_cmd()
+#[test]
+fn existing_import_map_mixed_with_remote() {
+  let _server = http_server();
+  let deno_dir = new_deno_dir();
+  let t = TempDir::new();
+  t.write(
+    "mod.ts",
+    "import {Logger} from 'http://localhost:4545/vendor/logger.ts';",
+  );
+
+  let status = util::deno_cmd_with_deno_dir(&deno_dir)
+    .current_dir(t.path())
+    .arg("vendor")
+    .arg("mod.ts")
+    .spawn()
+    .unwrap()
+    .wait()
+    .unwrap();
+  assert!(status.success());
+
+  assert_eq!(
+    t.read_to_string("vendor/import_map.json"),
+    r#"{
+  "imports": {
+    "http://localhost:4545/": "./localhost_4545/"
+  }
+}
+"#,
+  );
+
+  // make the import map specific to support vendoring mod.ts in the next step
+  t.write(
+    "vendor/import_map.json",
+    r#"{
+  "imports": {
+    "http://localhost:4545/vendor/logger.ts": "./localhost_4545/vendor/logger.ts"
+  }
+}
+"#,
+  );
+
+  t.write(
+    "mod.ts",
+    concat!(
+      "import {Logger} from 'http://localhost:4545/vendor/logger.ts';\n",
+      "import {Logger as OtherLogger} from 'http://localhost:4545/vendor/mod.ts';\n",
+    ),
+  );
+
+  // now vendor with the existing import map in a separate vendor directory
+  let deno = util::deno_cmd_with_deno_dir(&deno_dir)
+    .env("NO_COLOR", "1")
     .current_dir(t.path())
     .arg("vendor")
     .arg("mod.ts")
     .arg("--import-map")
-    .arg("imports.json")
+    .arg("vendor/import_map.json")
+    .arg("--output")
+    .arg("vendor2")
+    .stderr(Stdio::piped())
+    .spawn()
+    .unwrap();
+  let output = deno.wait_with_output().unwrap();
+  assert_eq!(
+    String::from_utf8_lossy(&output.stderr).trim(),
+    format!(
+      concat!("Download http://localhost:4545/vendor/mod.ts\n", "{}",),
+      success_text("1 module", "vendor2", true),
+    )
+  );
+  assert!(output.status.success());
+
+  // tricky scenario here where the output directory now contains a mapping
+  // back to the previous vendor location
+  assert_eq!(
+    t.read_to_string("vendor2/import_map.json"),
+    r#"{
+  "imports": {
+    "http://localhost:4545/vendor/logger.ts": "../vendor/localhost_4545/vendor/logger.ts",
+    "http://localhost:4545/": "./localhost_4545/"
+  },
+  "scopes": {
+    "./localhost_4545/": {
+      "./localhost_4545/vendor/logger.ts": "../vendor/localhost_4545/vendor/logger.ts"
+    }
+  }
+}
+"#,
+  );
+
+  // ensure it runs
+  let status = util::deno_cmd()
+    .current_dir(t.path())
+    .arg("run")
+    .arg("--check")
+    .arg("--no-remote")
+    .arg("--import-map")
+    .arg("vendor2/import_map.json")
+    .arg("mod.ts")
     .spawn()
     .unwrap()
     .wait()
     .unwrap();
   assert!(status.success());
-  // it should not have found any remote dependencies because
-  // the provided import map mapped it to a local directory
-  assert!(!vendor_dir.join("import_map.json").exists());
 }
 
 #[test]
 fn dynamic_import() {
   let _server = http_server();
   let t = TempDir::new();
-  let vendor_dir = t.path().join("vendor");
-  fs::write(
-    t.path().join("mod.ts"),
+  t.write(
+    "mod.ts",
     "import {Logger} from 'http://localhost:4545/vendor/dynamic.ts'; new Logger().log('outputted');",
-  ).unwrap();
+  );
 
   let status = util::deno_cmd()
     .current_dir(t.path())
@@ -290,10 +396,8 @@ fn dynamic_import() {
     .wait()
     .unwrap();
   assert!(status.success());
-  let import_map: serde_json::Value = serde_json::from_str(
-    &fs::read_to_string(vendor_dir.join("import_map.json")).unwrap(),
-  )
-  .unwrap();
+  let import_map: serde_json::Value =
+    serde_json::from_str(&t.read_to_string("vendor/import_map.json")).unwrap();
   assert_eq!(
     import_map,
     json!({
@@ -310,7 +414,8 @@ fn dynamic_import() {
     .arg("run")
     .arg("--allow-read=.")
     .arg("--no-remote")
-    .arg("--no-check")
+    .arg("--check")
+    .arg("--quiet")
     .arg("--import-map")
     .arg("vendor/import_map.json")
     .arg("mod.ts")
@@ -328,10 +433,10 @@ fn dynamic_import() {
 fn dynamic_non_analyzable_import() {
   let _server = http_server();
   let t = TempDir::new();
-  fs::write(
-    t.path().join("mod.ts"),
+  t.write(
+    "mod.ts",
     "import {Logger} from 'http://localhost:4545/vendor/dynamic_non_analyzable.ts'; new Logger().log('outputted');",
-  ).unwrap();
+  );
 
   let deno = util::deno_cmd()
     .current_dir(t.path())
@@ -350,23 +455,89 @@ fn dynamic_non_analyzable_import() {
     String::from_utf8_lossy(&output.stderr).trim(),
     format!(
       "Download http://localhost:4545/vendor/dynamic_non_analyzable.ts\n{}",
-      success_text("1 module", "vendor/", "mod.ts"),
+      success_text("1 module", "vendor/", true),
     )
   );
   assert_eq!(String::from_utf8_lossy(&output.stdout).trim(), "");
   assert!(output.status.success());
 }
 
-fn success_text(module_count: &str, dir: &str, entry_point: &str) -> String {
-  format!(
-    concat!(
-      "Vendored {} into {} directory.\n\n",
-      "To use vendored modules, specify the `--import-map` flag when invoking deno subcommands:\n",
-      "  deno run -A --import-map {} {}"
-    ),
-    module_count,
-    dir,
-    PathBuf::from(dir).join("import_map.json").display(),
-    entry_point,
-  )
+#[test]
+fn update_existing_config_test() {
+  let _server = http_server();
+  let t = TempDir::new();
+  t.write(
+    "my_app.ts",
+    "import {Logger} from 'http://localhost:4545/vendor/logger.ts'; new Logger().log('outputted');",
+  );
+  t.write("deno.json", "{\n}");
+
+  let deno = util::deno_cmd()
+    .current_dir(t.path())
+    .arg("vendor")
+    .arg("my_app.ts")
+    .arg("--output")
+    .arg("vendor2")
+    .env("NO_COLOR", "1")
+    .stdout(Stdio::piped())
+    .stderr(Stdio::piped())
+    .spawn()
+    .unwrap();
+  let output = deno.wait_with_output().unwrap();
+  assert_eq!(
+    String::from_utf8_lossy(&output.stderr).trim(),
+    format!(
+      concat!(
+        "Download http://localhost:4545/vendor/logger.ts\n",
+        "Vendored 1 module into vendor2 directory.\n\n",
+        "Updated your local Deno configuration file with a reference to the ",
+        "new vendored import map at {}. Invoking Deno subcommands will ",
+        "now automatically resolve using the vendored modules. You may override ",
+        "this by providing the `--import-map <other-import-map>` flag or by ",
+        "manually editing your Deno configuration file."
+      ),
+      PathBuf::from("vendor2").join("import_map.json").display(),
+    )
+  );
+  assert_eq!(String::from_utf8_lossy(&output.stdout).trim(), "");
+  assert!(output.status.success());
+
+  // try running the output with `--no-remote` and not specifying a `--vendor`
+  let deno = util::deno_cmd()
+    .current_dir(t.path())
+    .env("NO_COLOR", "1")
+    .arg("run")
+    .arg("--no-remote")
+    .arg("--check")
+    .arg("--quiet")
+    .arg("my_app.ts")
+    .stdout(Stdio::piped())
+    .stderr(Stdio::piped())
+    .spawn()
+    .unwrap();
+  let output = deno.wait_with_output().unwrap();
+  assert_eq!(String::from_utf8_lossy(&output.stderr).trim(), "");
+  assert_eq!(String::from_utf8_lossy(&output.stdout).trim(), "outputted");
+  assert!(output.status.success());
+}
+
+fn success_text(module_count: &str, dir: &str, has_import_map: bool) -> String {
+  let mut text = format!("Vendored {} into {} directory.", module_count, dir);
+  if has_import_map {
+    text.push_str(&
+      format!(
+        concat!(
+          "\n\nTo use vendored modules, specify the `--import-map {}import_map.json` flag when ",
+          r#"invoking Deno subcommands or add an `"importMap": "<path_to_vendored_import_map>"` "#,
+          "entry to a deno.json file.",
+        ),
+        if dir != "vendor/" {
+          format!("{}{}", dir.trim_end_matches('/'), if cfg!(windows) { '\\' } else {'/'})
+        } else {
+          dir.to_string()
+        }
+      )
+    );
+  }
+  text
 }
diff --git a/cli/tests/testdata/vendor/mod.ts b/cli/tests/testdata/vendor/mod.ts
new file mode 100644
index 000000000..8824d1b2a
--- /dev/null
+++ b/cli/tests/testdata/vendor/mod.ts
@@ -0,0 +1 @@
+export * from "./logger.ts";
diff --git a/cli/tools/vendor/build.rs b/cli/tools/vendor/build.rs
index dd362ebfb..ecb7db717 100644
--- a/cli/tools/vendor/build.rs
+++ b/cli/tools/vendor/build.rs
@@ -1,11 +1,17 @@
 // Copyright 2018-2022 the Deno authors. All rights reserved. MIT license.
 
 use std::path::Path;
+use std::path::PathBuf;
 
+use deno_ast::ModuleSpecifier;
+use deno_core::anyhow::bail;
+use deno_core::anyhow::Context;
 use deno_core::error::AnyError;
 use deno_graph::Module;
 use deno_graph::ModuleGraph;
 use deno_graph::ModuleKind;
+use import_map::ImportMap;
+use import_map::SpecifierMap;
 
 use super::analyze::has_default_export;
 use super::import_map::build_import_map;
@@ -15,29 +21,53 @@ use super::specifiers::is_remote_specifier;
 
 /// Allows substituting the environment for testing purposes.
 pub trait VendorEnvironment {
+  fn cwd(&self) -> Result<PathBuf, AnyError>;
   fn create_dir_all(&self, dir_path: &Path) -> Result<(), AnyError>;
   fn write_file(&self, file_path: &Path, text: &str) -> Result<(), AnyError>;
+  fn path_exists(&self, path: &Path) -> bool;
 }
 
 pub struct RealVendorEnvironment;
 
 impl VendorEnvironment for RealVendorEnvironment {
+  fn cwd(&self) -> Result<PathBuf, AnyError> {
+    Ok(std::env::current_dir()?)
+  }
+
   fn create_dir_all(&self, dir_path: &Path) -> Result<(), AnyError> {
     Ok(std::fs::create_dir_all(dir_path)?)
   }
 
   fn write_file(&self, file_path: &Path, text: &str) -> Result<(), AnyError> {
-    Ok(std::fs::write(file_path, text)?)
+    std::fs::write(file_path, text)
+      .with_context(|| format!("Failed writing {}", file_path.display()))
+  }
+
+  fn path_exists(&self, path: &Path) -> bool {
+    path.exists()
   }
 }
 
 /// Vendors remote modules and returns how many were vendored.
 pub fn build(
-  graph: &ModuleGraph,
+  graph: ModuleGraph,
   output_dir: &Path,
+  original_import_map: Option<&ImportMap>,
   environment: &impl VendorEnvironment,
 ) -> Result<usize, AnyError> {
   assert!(output_dir.is_absolute());
+  let output_dir_specifier =
+    ModuleSpecifier::from_directory_path(output_dir).unwrap();
+
+  if let Some(original_im) = &original_import_map {
+    validate_original_import_map(original_im, &output_dir_specifier)?;
+  }
+
+  // build the graph
+  graph.lock()?;
+  graph.valid()?;
+
+  // figure out how to map remote modules to local
   let all_modules = graph.modules();
   let remote_modules = all_modules
     .iter()
@@ -45,7 +75,7 @@ pub fn build(
     .copied()
     .collect::<Vec<_>>();
   let mappings =
-    Mappings::from_remote_modules(graph, &remote_modules, output_dir)?;
+    Mappings::from_remote_modules(&graph, &remote_modules, output_dir)?;
 
   // write out all the files
   for module in &remote_modules {
@@ -77,16 +107,59 @@ pub fn build(
     environment.write_file(&proxy_path, &text)?;
   }
 
-  // create the import map
-  if !mappings.base_specifiers().is_empty() {
-    let import_map_text = build_import_map(graph, &all_modules, &mappings);
-    environment
-      .write_file(&output_dir.join("import_map.json"), &import_map_text)?;
+  // create the import map if necessary
+  if !remote_modules.is_empty() {
+    let import_map_path = output_dir.join("import_map.json");
+    let import_map_text = build_import_map(
+      &output_dir_specifier,
+      &graph,
+      &all_modules,
+      &mappings,
+      original_import_map,
+    );
+    environment.write_file(&import_map_path, &import_map_text)?;
   }
 
   Ok(remote_modules.len())
 }
 
+fn validate_original_import_map(
+  import_map: &ImportMap,
+  output_dir: &ModuleSpecifier,
+) -> Result<(), AnyError> {
+  fn validate_imports(
+    imports: &SpecifierMap,
+    output_dir: &ModuleSpecifier,
+  ) -> Result<(), AnyError> {
+    for entry in imports.entries() {
+      if let Some(value) = entry.value {
+        if value.as_str().starts_with(output_dir.as_str()) {
+          bail!(
+            "Providing an existing import map with entries for the output directory is not supported (\"{}\": \"{}\").",
+            entry.raw_key,
+            entry.raw_value.unwrap_or("<INVALID>"),
+          );
+        }
+      }
+    }
+    Ok(())
+  }
+
+  validate_imports(import_map.imports(), output_dir)?;
+
+  for scope in import_map.scopes() {
+    if scope.key.starts_with(output_dir.as_str()) {
+      bail!(
+        "Providing an existing import map with a scope for the output directory is not supported (\"{}\").",
+        scope.raw_key,
+      );
+    }
+    validate_imports(scope.imports, output_dir)?;
+  }
+
+  Ok(())
+}
+
 fn build_proxy_module_source(
   module: &Module,
   proxied_module: &ProxiedModule,
@@ -171,9 +244,9 @@ mod test {
       output.import_map,
       Some(json!({
         "imports": {
-          "https://localhost/": "./localhost/",
           "https://localhost/other.ts?test": "./localhost/other.ts",
           "https://localhost/redirect.ts": "./localhost/mod.ts",
+          "https://localhost/": "./localhost/",
         }
       }))
     );
@@ -241,7 +314,7 @@ mod test {
         "imports": {
           "https://localhost/": "./localhost/",
           "https://localhost/redirect.ts": "./localhost/other.ts",
-          "https://other/": "./other/"
+          "https://other/": "./other/",
         },
         "scopes": {
           "./localhost/": {
@@ -313,10 +386,10 @@ mod test {
       output.import_map,
       Some(json!({
         "imports": {
-          "https://localhost/": "./localhost/",
           "https://localhost/mod.TS": "./localhost/mod_2.TS",
           "https://localhost/mod.ts": "./localhost/mod_3.ts",
           "https://localhost/mod.ts?test": "./localhost/mod_4.ts",
+          "https://localhost/": "./localhost/",
         }
       }))
     );
@@ -543,8 +616,8 @@ mod test {
       output.import_map,
       Some(json!({
         "imports": {
-          "http://localhost:4545/": "./localhost_4545/",
           "http://localhost:4545/sub/logger/mod.ts?testing": "./localhost_4545/sub/logger/mod.ts",
+          "http://localhost:4545/": "./localhost_4545/",
         },
         "scopes": {
           "./localhost_4545/": {
@@ -599,9 +672,9 @@ mod test {
       output.import_map,
       Some(json!({
         "imports": {
+          "https://localhost/std/hash/mod.ts": "./localhost/std@0.1.0/hash/mod.ts",
           "https://localhost/": "./localhost/",
-          "https://localhost/std/hash/mod.ts": "./localhost/std@0.1.0/hash/mod.ts"
-        }
+        },
       }))
     );
     assert_eq!(
@@ -675,6 +748,254 @@ mod test {
     );
   }
 
+  #[tokio::test]
+  async fn existing_import_map_basic() {
+    let mut builder = VendorTestBuilder::with_default_setup();
+    let mut original_import_map = builder.new_import_map("/import_map2.json");
+    original_import_map
+      .imports_mut()
+      .append(
+        "https://localhost/mod.ts".to_string(),
+        "./local_vendor/mod.ts".to_string(),
+      )
+      .unwrap();
+    let local_vendor_scope = original_import_map
+      .get_or_append_scope_mut("./local_vendor/")
+      .unwrap();
+    local_vendor_scope
+      .append(
+        "https://localhost/logger.ts".to_string(),
+        "./local_vendor/logger.ts".to_string(),
+      )
+      .unwrap();
+    local_vendor_scope
+      .append(
+        "/console_logger.ts".to_string(),
+        "./local_vendor/console_logger.ts".to_string(),
+      )
+      .unwrap();
+
+    let output = builder
+      .with_loader(|loader| {
+        loader.add("/mod.ts", "import 'https://localhost/mod.ts'; import 'https://localhost/other.ts';");
+        loader.add("/local_vendor/mod.ts", "import 'https://localhost/logger.ts'; import '/console_logger.ts'; console.log(5);");
+        loader.add("/local_vendor/logger.ts", "export class Logger {}");
+        loader.add("/local_vendor/console_logger.ts", "export class ConsoleLogger {}");
+        loader.add("https://localhost/mod.ts", "console.log(6);");
+        loader.add("https://localhost/other.ts", "import './mod.ts';");
+      })
+      .set_original_import_map(original_import_map.clone())
+      .build()
+      .await
+      .unwrap();
+
+    assert_eq!(
+      output.import_map,
+      Some(json!({
+        "imports": {
+          "https://localhost/mod.ts": "../local_vendor/mod.ts",
+          "https://localhost/": "./localhost/"
+        },
+        "scopes": {
+          "../local_vendor/": {
+            "https://localhost/logger.ts": "../local_vendor/logger.ts",
+            "/console_logger.ts": "../local_vendor/console_logger.ts",
+          },
+          "./localhost/": {
+            "./localhost/mod.ts": "../local_vendor/mod.ts",
+          },
+        }
+      }))
+    );
+    assert_eq!(
+      output.files,
+      to_file_vec(&[("/vendor/localhost/other.ts", "import './mod.ts';")]),
+    );
+  }
+
+  #[tokio::test]
+  async fn existing_import_map_mapped_bare_specifier() {
+    let mut builder = VendorTestBuilder::with_default_setup();
+    let mut original_import_map = builder.new_import_map("/import_map.json");
+    let imports = original_import_map.imports_mut();
+    imports
+      .append("$fresh".to_string(), "https://localhost/fresh".to_string())
+      .unwrap();
+    imports
+      .append("std/".to_string(), "https://deno.land/std/".to_string())
+      .unwrap();
+    let output = builder
+      .with_loader(|loader| {
+        loader.add("/mod.ts", "import 'std/mod.ts'; import '$fresh';");
+        loader.add("https://deno.land/std/mod.ts", "export function test() {}");
+        loader.add_with_headers(
+          "https://localhost/fresh",
+          "export function fresh() {}",
+          &[("content-type", "application/typescript")],
+        );
+      })
+      .set_original_import_map(original_import_map.clone())
+      .build()
+      .await
+      .unwrap();
+
+    assert_eq!(
+      output.import_map,
+      Some(json!({
+        "imports": {
+          "https://deno.land/": "./deno.land/",
+          "https://localhost/": "./localhost/",
+          "$fresh": "./localhost/fresh.ts",
+          "std/mod.ts": "./deno.land/std/mod.ts",
+        },
+      }))
+    );
+    assert_eq!(
+      output.files,
+      to_file_vec(&[
+        ("/vendor/deno.land/std/mod.ts", "export function test() {}"),
+        ("/vendor/localhost/fresh.ts", "export function fresh() {}")
+      ]),
+    );
+  }
+
+  #[tokio::test]
+  async fn existing_import_map_remote_absolute_specifier_local() {
+    let mut builder = VendorTestBuilder::with_default_setup();
+    let mut original_import_map = builder.new_import_map("/import_map.json");
+    original_import_map
+      .imports_mut()
+      .append(
+        "https://localhost/logger.ts?test".to_string(),
+        "./local/logger.ts".to_string(),
+      )
+      .unwrap();
+
+    let output = builder
+      .with_loader(|loader| {
+        loader.add("/mod.ts", "import 'https://localhost/mod.ts'; import 'https://localhost/logger.ts?test';");
+        loader.add("/local/logger.ts", "export class Logger {}");
+        // absolute specifier in a remote module that will point at ./local/logger.ts
+        loader.add("https://localhost/mod.ts", "import '/logger.ts?test';");
+        loader.add("https://localhost/logger.ts?test", "export class Logger {}");
+      })
+      .set_original_import_map(original_import_map.clone())
+      .build()
+      .await
+      .unwrap();
+
+    assert_eq!(
+      output.import_map,
+      Some(json!({
+        "imports": {
+          "https://localhost/logger.ts?test": "../local/logger.ts",
+          "https://localhost/": "./localhost/",
+        },
+        "scopes": {
+          "./localhost/": {
+            "/logger.ts?test": "../local/logger.ts",
+          },
+        }
+      }))
+    );
+    assert_eq!(
+      output.files,
+      to_file_vec(&[("/vendor/localhost/mod.ts", "import '/logger.ts?test';")]),
+    );
+  }
+
+  #[tokio::test]
+  async fn existing_import_map_imports_output_dir() {
+    let mut builder = VendorTestBuilder::with_default_setup();
+    let mut original_import_map = builder.new_import_map("/import_map.json");
+    original_import_map
+      .imports_mut()
+      .append(
+        "std/mod.ts".to_string(),
+        "./vendor/deno.land/std/mod.ts".to_string(),
+      )
+      .unwrap();
+    let err = builder
+      .with_loader(|loader| {
+        loader.add("/mod.ts", "import 'std/mod.ts';");
+        loader.add("/vendor/deno.land/std/mod.ts", "export function f() {}");
+        loader.add("https://deno.land/std/mod.ts", "export function f() {}");
+      })
+      .set_original_import_map(original_import_map.clone())
+      .build()
+      .await
+      .err()
+      .unwrap();
+
+    assert_eq!(
+      err.to_string(),
+      concat!(
+        "Providing an existing import map with entries for the output ",
+        "directory is not supported ",
+        "(\"std/mod.ts\": \"./vendor/deno.land/std/mod.ts\").",
+      )
+    );
+  }
+
+  #[tokio::test]
+  async fn existing_import_map_scopes_entry_output_dir() {
+    let mut builder = VendorTestBuilder::with_default_setup();
+    let mut original_import_map = builder.new_import_map("/import_map.json");
+    let scopes = original_import_map
+      .get_or_append_scope_mut("./other/")
+      .unwrap();
+    scopes
+      .append("/mod.ts".to_string(), "./vendor/mod.ts".to_string())
+      .unwrap();
+    let err = builder
+      .with_loader(|loader| {
+        loader.add("/mod.ts", "console.log(5);");
+      })
+      .set_original_import_map(original_import_map.clone())
+      .build()
+      .await
+      .err()
+      .unwrap();
+
+    assert_eq!(
+      err.to_string(),
+      concat!(
+        "Providing an existing import map with entries for the output ",
+        "directory is not supported ",
+        "(\"/mod.ts\": \"./vendor/mod.ts\").",
+      )
+    );
+  }
+
+  #[tokio::test]
+  async fn existing_import_map_scopes_key_output_dir() {
+    let mut builder = VendorTestBuilder::with_default_setup();
+    let mut original_import_map = builder.new_import_map("/import_map.json");
+    let scopes = original_import_map
+      .get_or_append_scope_mut("./vendor/")
+      .unwrap();
+    scopes
+      .append("/mod.ts".to_string(), "./vendor/mod.ts".to_string())
+      .unwrap();
+    let err = builder
+      .with_loader(|loader| {
+        loader.add("/mod.ts", "console.log(5);");
+      })
+      .set_original_import_map(original_import_map.clone())
+      .build()
+      .await
+      .err()
+      .unwrap();
+
+    assert_eq!(
+      err.to_string(),
+      concat!(
+        "Providing an existing import map with a scope for the output ",
+        "directory is not supported (\"./vendor/\").",
+      )
+    );
+  }
+
   fn to_file_vec(items: &[(&str, &str)]) -> Vec<(String, String)> {
     items
       .iter()
diff --git a/cli/tools/vendor/import_map.rs b/cli/tools/vendor/import_map.rs
index 1b2a2e263..e03260e3e 100644
--- a/cli/tools/vendor/import_map.rs
+++ b/cli/tools/vendor/import_map.rs
@@ -1,44 +1,43 @@
 // Copyright 2018-2022 the Deno authors. All rights reserved. MIT license.
 
-use std::collections::BTreeMap;
-
 use deno_ast::LineAndColumnIndex;
 use deno_ast::ModuleSpecifier;
 use deno_ast::SourceTextInfo;
-use deno_core::serde_json;
 use deno_graph::Module;
 use deno_graph::ModuleGraph;
 use deno_graph::Position;
 use deno_graph::Range;
 use deno_graph::Resolved;
-use serde::Serialize;
+use import_map::ImportMap;
+use import_map::SpecifierMap;
+use indexmap::IndexMap;
+use log::warn;
 
 use super::mappings::Mappings;
 use super::specifiers::is_remote_specifier;
 use super::specifiers::is_remote_specifier_text;
 
-#[derive(Serialize)]
-struct SerializableImportMap {
-  imports: BTreeMap<String, String>,
-  #[serde(skip_serializing_if = "BTreeMap::is_empty")]
-  scopes: BTreeMap<String, BTreeMap<String, String>>,
-}
-
 struct ImportMapBuilder<'a> {
+  base_dir: &'a ModuleSpecifier,
   mappings: &'a Mappings,
   imports: ImportsBuilder<'a>,
-  scopes: BTreeMap<String, ImportsBuilder<'a>>,
+  scopes: IndexMap<String, ImportsBuilder<'a>>,
 }
 
 impl<'a> ImportMapBuilder<'a> {
-  pub fn new(mappings: &'a Mappings) -> Self {
+  pub fn new(base_dir: &'a ModuleSpecifier, mappings: &'a Mappings) -> Self {
     ImportMapBuilder {
+      base_dir,
       mappings,
-      imports: ImportsBuilder::new(mappings),
+      imports: ImportsBuilder::new(base_dir, mappings),
       scopes: Default::default(),
     }
   }
 
+  pub fn base_dir(&self) -> &ModuleSpecifier {
+    self.base_dir
+  }
+
   pub fn scope(
     &mut self,
     base_specifier: &ModuleSpecifier,
@@ -48,38 +47,115 @@ impl<'a> ImportMapBuilder<'a> {
       .entry(
         self
           .mappings
-          .relative_specifier_text(self.mappings.output_dir(), base_specifier),
+          .relative_specifier_text(self.base_dir, base_specifier),
       )
-      .or_insert_with(|| ImportsBuilder::new(self.mappings))
+      .or_insert_with(|| ImportsBuilder::new(self.base_dir, self.mappings))
   }
 
-  pub fn into_serializable(self) -> SerializableImportMap {
-    SerializableImportMap {
-      imports: self.imports.imports,
-      scopes: self
-        .scopes
-        .into_iter()
-        .map(|(key, value)| (key, value.imports))
-        .collect(),
+  pub fn into_import_map(
+    self,
+    original_import_map: Option<&ImportMap>,
+  ) -> ImportMap {
+    fn get_local_imports(
+      new_relative_path: &str,
+      original_imports: &SpecifierMap,
+    ) -> Vec<(String, String)> {
+      let mut result = Vec::new();
+      for entry in original_imports.entries() {
+        if let Some(raw_value) = entry.raw_value {
+          if raw_value.starts_with("./") || raw_value.starts_with("../") {
+            let sub_index = raw_value.find('/').unwrap() + 1;
+            result.push((
+              entry.raw_key.to_string(),
+              format!("{}{}", new_relative_path, &raw_value[sub_index..]),
+            ));
+          }
+        }
+      }
+      result
+    }
+
+    fn add_local_imports<'a>(
+      new_relative_path: &str,
+      original_imports: &SpecifierMap,
+      get_new_imports: impl FnOnce() -> &'a mut SpecifierMap,
+    ) {
+      let local_imports =
+        get_local_imports(new_relative_path, original_imports);
+      if !local_imports.is_empty() {
+        let new_imports = get_new_imports();
+        for (key, value) in local_imports {
+          if let Err(warning) = new_imports.append(key, value) {
+            warn!("{}", warning);
+          }
+        }
+      }
+    }
+
+    let mut import_map = ImportMap::new(self.base_dir.clone());
+
+    if let Some(original_im) = original_import_map {
+      let original_base_dir = ModuleSpecifier::from_directory_path(
+        original_im
+          .base_url()
+          .to_file_path()
+          .unwrap()
+          .parent()
+          .unwrap(),
+      )
+      .unwrap();
+      let new_relative_path = self
+        .mappings
+        .relative_specifier_text(self.base_dir, &original_base_dir);
+      // add the imports
+      add_local_imports(&new_relative_path, original_im.imports(), || {
+        import_map.imports_mut()
+      });
+
+      for scope in original_im.scopes() {
+        if scope.raw_key.starts_with("./") || scope.raw_key.starts_with("../") {
+          let sub_index = scope.raw_key.find('/').unwrap() + 1;
+          let new_key =
+            format!("{}{}", new_relative_path, &scope.raw_key[sub_index..]);
+          add_local_imports(&new_relative_path, scope.imports, || {
+            import_map.get_or_append_scope_mut(&new_key).unwrap()
+          });
+        }
+      }
     }
-  }
 
-  pub fn into_file_text(self) -> String {
-    let mut text =
-      serde_json::to_string_pretty(&self.into_serializable()).unwrap();
-    text.push('\n');
-    text
+    let imports = import_map.imports_mut();
+    for (key, value) in self.imports.imports {
+      if !imports.contains(&key) {
+        imports.append(key, value).unwrap();
+      }
+    }
+
+    for (scope_key, scope_value) in self.scopes {
+      if !scope_value.imports.is_empty() {
+        let imports = import_map.get_or_append_scope_mut(&scope_key).unwrap();
+        for (key, value) in scope_value.imports {
+          if !imports.contains(&key) {
+            imports.append(key, value).unwrap();
+          }
+        }
+      }
+    }
+
+    import_map
   }
 }
 
 struct ImportsBuilder<'a> {
+  base_dir: &'a ModuleSpecifier,
   mappings: &'a Mappings,
-  imports: BTreeMap<String, String>,
+  imports: IndexMap<String, String>,
 }
 
 impl<'a> ImportsBuilder<'a> {
-  pub fn new(mappings: &'a Mappings) -> Self {
+  pub fn new(base_dir: &'a ModuleSpecifier, mappings: &'a Mappings) -> Self {
     Self {
+      base_dir,
       mappings,
       imports: Default::default(),
     }
@@ -88,7 +164,7 @@ impl<'a> ImportsBuilder<'a> {
   pub fn add(&mut self, key: String, specifier: &ModuleSpecifier) {
     let value = self
       .mappings
-      .relative_specifier_text(self.mappings.output_dir(), specifier);
+      .relative_specifier_text(self.base_dir, specifier);
 
     // skip creating identity entries
     if key != value {
@@ -98,20 +174,22 @@ impl<'a> ImportsBuilder<'a> {
 }
 
 pub fn build_import_map(
+  base_dir: &ModuleSpecifier,
   graph: &ModuleGraph,
   modules: &[&Module],
   mappings: &Mappings,
+  original_import_map: Option<&ImportMap>,
 ) -> String {
-  let mut import_map = ImportMapBuilder::new(mappings);
-  visit_modules(graph, modules, mappings, &mut import_map);
+  let mut builder = ImportMapBuilder::new(base_dir, mappings);
+  visit_modules(graph, modules, mappings, &mut builder);
 
   for base_specifier in mappings.base_specifiers() {
-    import_map
+    builder
       .imports
       .add(base_specifier.to_string(), base_specifier);
   }
 
-  import_map.into_file_text()
+  builder.into_import_map(original_import_map).to_json()
 }
 
 fn visit_modules(
@@ -197,37 +275,70 @@ fn handle_dep_specifier(
   mappings: &Mappings,
 ) {
   let specifier = graph.resolve(unresolved_specifier);
-  // do not handle specifiers pointing at local modules
-  if !is_remote_specifier(&specifier) {
-    return;
+  // check if it's referencing a remote module
+  if is_remote_specifier(&specifier) {
+    handle_remote_dep_specifier(
+      text,
+      unresolved_specifier,
+      &specifier,
+      import_map,
+      referrer,
+      mappings,
+    )
+  } else {
+    handle_local_dep_specifier(
+      text,
+      unresolved_specifier,
+      &specifier,
+      import_map,
+      referrer,
+      mappings,
+    );
   }
+}
 
-  let base_specifier = mappings.base_specifier(&specifier);
+fn handle_remote_dep_specifier(
+  text: &str,
+  unresolved_specifier: &ModuleSpecifier,
+  specifier: &ModuleSpecifier,
+  import_map: &mut ImportMapBuilder,
+  referrer: &ModuleSpecifier,
+  mappings: &Mappings,
+) {
   if is_remote_specifier_text(text) {
+    let base_specifier = mappings.base_specifier(specifier);
     if !text.starts_with(base_specifier.as_str()) {
       panic!("Expected {} to start with {}", text, base_specifier);
     }
 
     let sub_path = &text[base_specifier.as_str().len()..];
-    let expected_relative_specifier_text =
-      mappings.relative_path(base_specifier, &specifier);
-    if expected_relative_specifier_text == sub_path {
-      return;
+    let relative_text =
+      mappings.relative_specifier_text(base_specifier, specifier);
+    let expected_sub_path = relative_text.trim_start_matches("./");
+    if expected_sub_path != sub_path {
+      import_map.imports.add(text.to_string(), specifier);
     }
-
-    import_map.imports.add(text.to_string(), &specifier);
   } else {
     let expected_relative_specifier_text =
-      mappings.relative_specifier_text(referrer, &specifier);
+      mappings.relative_specifier_text(referrer, specifier);
     if expected_relative_specifier_text == text {
       return;
     }
 
+    if !is_remote_specifier(referrer) {
+      // local module referencing a remote module using
+      // non-remote specifier text means it was something in
+      // the original import map, so add a mapping to it
+      import_map.imports.add(text.to_string(), specifier);
+      return;
+    }
+
+    let base_specifier = mappings.base_specifier(specifier);
+    let base_dir = import_map.base_dir().clone();
     let imports = import_map.scope(base_specifier);
     if text.starts_with("./") || text.starts_with("../") {
       // resolve relative specifier key
       let mut local_base_specifier = mappings.local_uri(base_specifier);
-      local_base_specifier.set_query(unresolved_specifier.query());
       local_base_specifier = local_base_specifier
         // path includes "/" so make it relative
         .join(&format!(".{}", unresolved_specifier.path()))
@@ -241,18 +352,15 @@ fn handle_dep_specifier(
       local_base_specifier.set_query(unresolved_specifier.query());
 
       imports.add(
-        mappings.relative_specifier_text(
-          mappings.output_dir(),
-          &local_base_specifier,
-        ),
-        &specifier,
+        mappings.relative_specifier_text(&base_dir, &local_base_specifier),
+        specifier,
       );
 
       // add a mapping that uses the local directory name and the remote
       // filename in order to support files importing this relatively
       imports.add(
         {
-          let local_path = mappings.local_path(&specifier);
+          let local_path = mappings.local_path(specifier);
           let mut value =
             ModuleSpecifier::from_directory_path(local_path.parent().unwrap())
               .unwrap();
@@ -262,17 +370,58 @@ fn handle_dep_specifier(
             value.path(),
             specifier.path_segments().unwrap().last().unwrap(),
           ));
-          mappings.relative_specifier_text(mappings.output_dir(), &value)
+          mappings.relative_specifier_text(&base_dir, &value)
         },
-        &specifier,
+        specifier,
       );
     } else {
       // absolute (`/`) or bare specifier should be left as-is
-      imports.add(text.to_string(), &specifier);
+      imports.add(text.to_string(), specifier);
     }
   }
 }
 
+fn handle_local_dep_specifier(
+  text: &str,
+  unresolved_specifier: &ModuleSpecifier,
+  specifier: &ModuleSpecifier,
+  import_map: &mut ImportMapBuilder,
+  referrer: &ModuleSpecifier,
+  mappings: &Mappings,
+) {
+  if !is_remote_specifier(referrer) {
+    // do not handle local modules referencing local modules
+    return;
+  }
+
+  // The remote module is referencing a local file. This could occur via an
+  // existing import map. In this case, we'll have to add an import map
+  // entry in order to map the path back to the local path once vendored.
+  let base_dir = import_map.base_dir().clone();
+  let base_specifier = mappings.base_specifier(referrer);
+  let imports = import_map.scope(base_specifier);
+
+  if text.starts_with("./") || text.starts_with("../") {
+    let referrer_local_uri = mappings.local_uri(referrer);
+    let mut specifier_local_uri =
+      referrer_local_uri.join(text).unwrap_or_else(|_| {
+        panic!(
+          "Error joining {} to {}",
+          unresolved_specifier.path(),
+          referrer_local_uri
+        )
+      });
+    specifier_local_uri.set_query(unresolved_specifier.query());
+
+    imports.add(
+      mappings.relative_specifier_text(&base_dir, &specifier_local_uri),
+      specifier,
+    );
+  } else {
+    imports.add(text.to_string(), specifier);
+  }
+}
+
 fn text_from_range<'a>(
   text_info: &SourceTextInfo,
   text: &'a str,
diff --git a/cli/tools/vendor/mappings.rs b/cli/tools/vendor/mappings.rs
index 2e85445dc..543536128 100644
--- a/cli/tools/vendor/mappings.rs
+++ b/cli/tools/vendor/mappings.rs
@@ -14,6 +14,7 @@ use deno_graph::Position;
 use deno_graph::Resolved;
 
 use crate::fs_util::path_with_stem_suffix;
+use crate::fs_util::relative_specifier;
 
 use super::specifiers::dir_name_for_root;
 use super::specifiers::get_unique_path;
@@ -28,7 +29,6 @@ pub struct ProxiedModule {
 
 /// Constructs and holds the remote specifier to local path mappings.
 pub struct Mappings {
-  output_dir: ModuleSpecifier,
   mappings: HashMap<ModuleSpecifier, PathBuf>,
   base_specifiers: Vec<ModuleSpecifier>,
   proxies: HashMap<ModuleSpecifier, ProxiedModule>,
@@ -104,17 +104,12 @@ impl Mappings {
     }
 
     Ok(Self {
-      output_dir: ModuleSpecifier::from_directory_path(output_dir).unwrap(),
       mappings,
       base_specifiers,
       proxies,
     })
   }
 
-  pub fn output_dir(&self) -> &ModuleSpecifier {
-    &self.output_dir
-  }
-
   pub fn local_uri(&self, specifier: &ModuleSpecifier) -> ModuleSpecifier {
     if specifier.scheme() == "file" {
       specifier.clone()
@@ -146,43 +141,14 @@ impl Mappings {
     }
   }
 
-  pub fn relative_path(
-    &self,
-    from: &ModuleSpecifier,
-    to: &ModuleSpecifier,
-  ) -> String {
-    let mut from = self.local_uri(from);
-    let to = self.local_uri(to);
-
-    // workaround using parent directory until https://github.com/servo/rust-url/pull/754 is merged
-    if !from.path().ends_with('/') {
-      let local_path = self.local_path(&from);
-      from = ModuleSpecifier::from_directory_path(local_path.parent().unwrap())
-        .unwrap();
-    }
-
-    // workaround for url crate not adding a trailing slash for a directory
-    // it seems to be fixed once a version greater than 2.2.2 is released
-    let is_dir = to.path().ends_with('/');
-    let mut text = from.make_relative(&to).unwrap();
-    if is_dir && !text.ends_with('/') && to.query().is_none() {
-      text.push('/');
-    }
-    text
-  }
-
   pub fn relative_specifier_text(
     &self,
     from: &ModuleSpecifier,
     to: &ModuleSpecifier,
   ) -> String {
-    let relative_path = self.relative_path(from, to);
-
-    if relative_path.starts_with("../") || relative_path.starts_with("./") {
-      relative_path
-    } else {
-      format!("./{}", relative_path)
-    }
+    let from = self.local_uri(from);
+    let to = self.local_uri(to);
+    relative_specifier(&from, &to).unwrap()
   }
 
   pub fn base_specifiers(&self) -> &Vec<ModuleSpecifier> {
diff --git a/cli/tools/vendor/mod.rs b/cli/tools/vendor/mod.rs
index 3a5455aae..69c759154 100644
--- a/cli/tools/vendor/mod.rs
+++ b/cli/tools/vendor/mod.rs
@@ -3,19 +3,24 @@
 use std::path::Path;
 use std::path::PathBuf;
 
+use deno_ast::ModuleSpecifier;
 use deno_core::anyhow::bail;
 use deno_core::anyhow::Context;
 use deno_core::error::AnyError;
 use deno_core::resolve_url_or_path;
 use deno_runtime::permissions::Permissions;
+use log::warn;
 
+use crate::config_file::FmtOptionsConfig;
 use crate::flags::VendorFlags;
 use crate::fs_util;
+use crate::fs_util::relative_specifier;
+use crate::fs_util::specifier_to_file_path;
 use crate::lockfile;
 use crate::proc_state::ProcState;
 use crate::resolver::ImportMapResolver;
 use crate::resolver::JsxResolver;
-use crate::tools::vendor::specifiers::is_remote_specifier_text;
+use crate::tools::fmt::format_json;
 
 mod analyze;
 mod build;
@@ -33,14 +38,15 @@ pub async fn vendor(ps: ProcState, flags: VendorFlags) -> Result<(), AnyError> {
   let output_dir = fs_util::resolve_from_cwd(&raw_output_dir)?;
   validate_output_dir(&output_dir, &flags, &ps)?;
   let graph = create_graph(&ps, &flags).await?;
-  let vendored_count =
-    build::build(&graph, &output_dir, &build::RealVendorEnvironment)?;
+  let vendored_count = build::build(
+    graph,
+    &output_dir,
+    ps.maybe_import_map.as_deref(),
+    &build::RealVendorEnvironment,
+  )?;
 
   eprintln!(
-    r#"Vendored {} {} into {} directory.
-
-To use vendored modules, specify the `--import-map` flag when invoking deno subcommands:
-  deno run -A --import-map {} {}"#,
+    concat!("Vendored {} {} into {} directory.",),
     vendored_count,
     if vendored_count == 1 {
       "module"
@@ -48,14 +54,31 @@ To use vendored modules, specify the `--import-map` flag when invoking deno subc
       "modules"
     },
     raw_output_dir.display(),
-    raw_output_dir.join("import_map.json").display(),
-    flags
-      .specifiers
-      .iter()
-      .map(|s| s.as_str())
-      .find(|s| !is_remote_specifier_text(s))
-      .unwrap_or("main.ts"),
   );
+  if vendored_count > 0 {
+    let import_map_path = raw_output_dir.join("import_map.json");
+    if maybe_update_config_file(&output_dir, &ps) {
+      eprintln!(
+        concat!(
+          "\nUpdated your local Deno configuration file with a reference to the ",
+          "new vendored import map at {}. Invoking Deno subcommands will now ",
+          "automatically resolve using the vendored modules. You may override ",
+          "this by providing the `--import-map <other-import-map>` flag or by ",
+          "manually editing your Deno configuration file.",
+        ),
+        import_map_path.display(),
+      );
+    } else {
+      eprintln!(
+        concat!(
+          "\nTo use vendored modules, specify the `--import-map {}` flag when ",
+          r#"invoking Deno subcommands or add an `"importMap": "<path_to_vendored_import_map>"` "#,
+          "entry to a deno.json file.",
+        ),
+        import_map_path.display(),
+      );
+    }
+  }
 
   Ok(())
 }
@@ -76,7 +99,7 @@ fn validate_output_dir(
   if let Some(import_map_path) = ps
     .maybe_import_map
     .as_ref()
-    .and_then(|m| m.base_url().to_file_path().ok())
+    .and_then(|m| specifier_to_file_path(m.base_url()).ok())
     .and_then(|p| fs_util::canonicalize_path(&p).ok())
   {
     // make the output directory in order to canonicalize it for the check below
@@ -87,10 +110,21 @@ fn validate_output_dir(
       })?;
 
     if import_map_path.starts_with(&output_dir) {
-      // We don't allow using the output directory to help generate the new state
-      // of itself because supporting this scenario adds a lot of complexity.
+      // canonicalize to make the test for this pass on the CI
+      let cwd = fs_util::canonicalize_path(&std::env::current_dir()?)?;
+      // We don't allow using the output directory to help generate the
+      // new state because this may lead to cryptic error messages.
       bail!(
-        "Using an import map found in the output directory is not supported."
+        concat!(
+          "Specifying an import map file ({}) in the deno vendor output ",
+          "directory is not supported. Please specify no import map or one ",
+          "located outside this directory."
+        ),
+        import_map_path
+          .strip_prefix(&cwd)
+          .unwrap_or(&import_map_path)
+          .display()
+          .to_string(),
       );
     }
   }
@@ -98,6 +132,104 @@ fn validate_output_dir(
   Ok(())
 }
 
+fn maybe_update_config_file(output_dir: &Path, ps: &ProcState) -> bool {
+  assert!(output_dir.is_absolute());
+  let config_file = match &ps.maybe_config_file {
+    Some(f) => f,
+    None => return false,
+  };
+  let fmt_config = config_file
+    .to_fmt_config()
+    .unwrap_or_default()
+    .unwrap_or_default();
+  let result = update_config_file(
+    &config_file.specifier,
+    &ModuleSpecifier::from_file_path(output_dir.join("import_map.json"))
+      .unwrap(),
+    &fmt_config.options,
+  );
+  match result {
+    Ok(()) => true,
+    Err(err) => {
+      warn!("Error updating config file. {:#}", err);
+      false
+    }
+  }
+}
+
+fn update_config_file(
+  config_specifier: &ModuleSpecifier,
+  import_map_specifier: &ModuleSpecifier,
+  fmt_options: &FmtOptionsConfig,
+) -> Result<(), AnyError> {
+  if config_specifier.scheme() != "file" {
+    return Ok(());
+  }
+
+  let config_path = specifier_to_file_path(config_specifier)?;
+  let config_text = std::fs::read_to_string(&config_path)?;
+  let relative_text =
+    match relative_specifier(config_specifier, import_map_specifier) {
+      Some(text) => text,
+      None => return Ok(()), // ignore
+    };
+  if let Some(new_text) =
+    update_config_text(&config_text, &relative_text, fmt_options)
+  {
+    std::fs::write(config_path, new_text)?;
+  }
+
+  Ok(())
+}
+
+fn update_config_text(
+  text: &str,
+  import_map_specifier: &str,
+  fmt_options: &FmtOptionsConfig,
+) -> Option<String> {
+  use jsonc_parser::ast::ObjectProp;
+  use jsonc_parser::ast::Value;
+  let ast = jsonc_parser::parse_to_ast(text, &Default::default()).ok()?;
+  let obj = match ast.value {
+    Some(Value::Object(obj)) => obj,
+    _ => return None, // shouldn't happen, so ignore
+  };
+  let import_map_specifier = import_map_specifier.replace('\"', "\\\"");
+
+  match obj.get("importMap") {
+    Some(ObjectProp {
+      value: Value::StringLit(lit),
+      ..
+    }) => Some(format!(
+      "{}{}{}",
+      &text[..lit.range.start + 1],
+      import_map_specifier,
+      &text[lit.range.end - 1..],
+    )),
+    None => {
+      // insert it crudely at a position that won't cause any issues
+      // with comments and format after to make it look nice
+      let insert_position = obj.range.end - 1;
+      let insert_text = format!(
+        r#"{}"importMap": "{}""#,
+        if obj.properties.is_empty() { "" } else { "," },
+        import_map_specifier
+      );
+      let new_text = format!(
+        "{}{}{}",
+        &text[..insert_position],
+        insert_text,
+        &text[insert_position..],
+      );
+      format_json(&new_text, fmt_options)
+        .ok()
+        .map(|formatted_text| formatted_text.unwrap_or(new_text))
+    }
+    // shouldn't happen, so ignore
+    Some(_) => None,
+  }
+}
+
 fn is_dir_empty(dir_path: &Path) -> Result<bool, AnyError> {
   match std::fs::read_dir(&dir_path) {
     Ok(mut dir) => Ok(dir.next().is_none()),
@@ -149,20 +281,85 @@ async fn create_graph(
       .map(|im| im.as_resolver())
   };
 
-  let graph = deno_graph::create_graph(
-    entry_points,
-    false,
-    maybe_imports,
-    &mut cache,
-    maybe_resolver,
-    maybe_locker,
-    None,
-    None,
+  Ok(
+    deno_graph::create_graph(
+      entry_points,
+      false,
+      maybe_imports,
+      &mut cache,
+      maybe_resolver,
+      maybe_locker,
+      None,
+      None,
+    )
+    .await,
   )
-  .await;
+}
 
-  graph.lock()?;
-  graph.valid()?;
+#[cfg(test)]
+mod internal_test {
+  use super::*;
+  use pretty_assertions::assert_eq;
 
-  Ok(graph)
+  #[test]
+  fn update_config_text_no_existing_props_add_prop() {
+    let text = update_config_text(
+      "{\n}",
+      "./vendor/import_map.json",
+      &Default::default(),
+    )
+    .unwrap();
+    assert_eq!(
+      text,
+      r#"{
+  "importMap": "./vendor/import_map.json"
+}
+"#
+    );
+  }
+
+  #[test]
+  fn update_config_text_existing_props_add_prop() {
+    let text = update_config_text(
+      r#"{
+  "tasks": {
+    "task1": "other"
+  }
+}
+"#,
+      "./vendor/import_map.json",
+      &Default::default(),
+    )
+    .unwrap();
+    assert_eq!(
+      text,
+      r#"{
+  "tasks": {
+    "task1": "other"
+  },
+  "importMap": "./vendor/import_map.json"
+}
+"#
+    );
+  }
+
+  #[test]
+  fn update_config_text_update_prop() {
+    let text = update_config_text(
+      r#"{
+  "importMap": "./local.json"
+}
+"#,
+      "./vendor/import_map.json",
+      &Default::default(),
+    )
+    .unwrap();
+    assert_eq!(
+      text,
+      r#"{
+  "importMap": "./vendor/import_map.json"
+}
+"#
+    );
+  }
 }
diff --git a/cli/tools/vendor/test.rs b/cli/tools/vendor/test.rs
index 5060c493a..7a8feb94b 100644
--- a/cli/tools/vendor/test.rs
+++ b/cli/tools/vendor/test.rs
@@ -5,6 +5,7 @@ use std::collections::HashMap;
 use std::collections::HashSet;
 use std::path::Path;
 use std::path::PathBuf;
+use std::sync::Arc;
 
 use deno_ast::ModuleSpecifier;
 use deno_core::anyhow::anyhow;
@@ -16,6 +17,10 @@ use deno_graph::source::LoadFuture;
 use deno_graph::source::LoadResponse;
 use deno_graph::source::Loader;
 use deno_graph::ModuleGraph;
+use deno_graph::ModuleKind;
+use import_map::ImportMap;
+
+use crate::resolver::ImportMapResolver;
 
 use super::build::VendorEnvironment;
 
@@ -120,6 +125,10 @@ struct TestVendorEnvironment {
 }
 
 impl VendorEnvironment for TestVendorEnvironment {
+  fn cwd(&self) -> Result<PathBuf, AnyError> {
+    Ok(make_path("/"))
+  }
+
   fn create_dir_all(&self, dir_path: &Path) -> Result<(), AnyError> {
     let mut directories = self.directories.borrow_mut();
     for path in dir_path.ancestors() {
@@ -141,6 +150,10 @@ impl VendorEnvironment for TestVendorEnvironment {
       .insert(file_path.to_path_buf(), text.to_string());
     Ok(())
   }
+
+  fn path_exists(&self, path: &Path) -> bool {
+    self.files.borrow().contains_key(&path.to_path_buf())
+  }
 }
 
 pub struct VendorOutput {
@@ -152,6 +165,8 @@ pub struct VendorOutput {
 pub struct VendorTestBuilder {
   entry_points: Vec<ModuleSpecifier>,
   loader: TestLoader,
+  original_import_map: Option<ImportMap>,
+  environment: TestVendorEnvironment,
 }
 
 impl VendorTestBuilder {
@@ -161,6 +176,19 @@ impl VendorTestBuilder {
     builder
   }
 
+  pub fn new_import_map(&self, base_path: &str) -> ImportMap {
+    let base = ModuleSpecifier::from_file_path(&make_path(base_path)).unwrap();
+    ImportMap::new(base)
+  }
+
+  pub fn set_original_import_map(
+    &mut self,
+    import_map: ImportMap,
+  ) -> &mut Self {
+    self.original_import_map = Some(import_map);
+    self
+  }
+
   pub fn add_entry_point(&mut self, entry_point: impl AsRef<str>) -> &mut Self {
     let entry_point = make_path(entry_point.as_ref());
     self
@@ -170,11 +198,24 @@ impl VendorTestBuilder {
   }
 
   pub async fn build(&mut self) -> Result<VendorOutput, AnyError> {
-    let graph = self.build_graph().await;
     let output_dir = make_path("/vendor");
-    let environment = TestVendorEnvironment::default();
-    super::build::build(&graph, &output_dir, &environment)?;
-    let mut files = environment.files.borrow_mut();
+    let roots = self
+      .entry_points
+      .iter()
+      .map(|s| (s.to_owned(), deno_graph::ModuleKind::Esm))
+      .collect();
+    let loader = self.loader.clone();
+    let graph =
+      build_test_graph(roots, self.original_import_map.clone(), loader.clone())
+        .await;
+    super::build::build(
+      graph,
+      &output_dir,
+      self.original_import_map.as_ref(),
+      &self.environment,
+    )?;
+
+    let mut files = self.environment.files.borrow_mut();
     let import_map = files.remove(&output_dir.join("import_map.json"));
     let mut files = files
       .iter()
@@ -193,27 +234,26 @@ impl VendorTestBuilder {
     action(&mut self.loader);
     self
   }
+}
 
-  async fn build_graph(&mut self) -> ModuleGraph {
-    let graph = deno_graph::create_graph(
-      self
-        .entry_points
-        .iter()
-        .map(|s| (s.to_owned(), deno_graph::ModuleKind::Esm))
-        .collect(),
-      false,
-      None,
-      &mut self.loader,
-      None,
-      None,
-      None,
-      None,
-    )
-    .await;
-    graph.lock().unwrap();
-    graph.valid().unwrap();
-    graph
-  }
+async fn build_test_graph(
+  roots: Vec<(ModuleSpecifier, ModuleKind)>,
+  original_import_map: Option<ImportMap>,
+  mut loader: TestLoader,
+) -> ModuleGraph {
+  let resolver =
+    original_import_map.map(|m| ImportMapResolver::new(Arc::new(m)));
+  deno_graph::create_graph(
+    roots,
+    false,
+    None,
+    &mut loader,
+    resolver.as_ref().map(|im| im.as_resolver()),
+    None,
+    None,
+    None,
+  )
+  .await
 }
 
 fn make_path(text: &str) -> PathBuf {