feat: OpenTelemetry Tracing API and Exporting (#26710)

Initial import of OTEL code supporting tracing. Metrics soon to come.
Implements APIs for https://jsr.io/@deno/otel so that code using
OpenTelemetry.js just works tm.

There is still a lot of work to do with configuration and adding
built-in tracing to core APIs, which will come in followup PRs.

---------

Co-authored-by: Luca Casonato <hello@lcas.dev>

6 files changed, 131 insertions, 0 deletions

diff --git a/cli/args/mod.rs b/cli/args/mod.rs
index e19025f8b..3aaf2bd43 100644
--- a/cli/args/mod.rs
+++ b/cli/args/mod.rs
@@ -27,6 +27,7 @@ use deno_npm::npm_rc::ResolvedNpmRc;
 use deno_npm::resolution::ValidSerializedNpmResolutionSnapshot;
 use deno_npm::NpmSystemInfo;
 use deno_path_util::normalize_path;
+use deno_runtime::ops::otel::OtelConfig;
 use deno_semver::npm::NpmPackageReqReference;
 use import_map::resolve_import_map_value_from_specifier;
 
@@ -1129,6 +1130,23 @@ impl CliOptions {
     }
   }
 
+  pub fn otel_config(&self) -> Option<OtelConfig> {
+    if self
+      .flags
+      .unstable_config
+      .features
+      .contains(&String::from("otel"))
+    {
+      Some(OtelConfig {
+        runtime_name: Cow::Borrowed("deno"),
+        runtime_version: Cow::Borrowed(crate::version::DENO_VERSION_INFO.deno),
+        ..Default::default()
+      })
+    } else {
+      None
+    }
+  }
+
   pub fn env_file_name(&self) -> Option<&String> {
     self.flags.env_file.as_ref()
   }
diff --git a/cli/factory.rs b/cli/factory.rs
index 4a36c75ba..417f771a3 100644
--- a/cli/factory.rs
+++ b/cli/factory.rs
@@ -939,6 +939,7 @@ impl CliFactory {
       StorageKeyResolver::from_options(cli_options),
       cli_options.sub_command().clone(),
       self.create_cli_main_worker_options()?,
+      self.cli_options()?.otel_config(),
     ))
   }
 
diff --git a/cli/standalone/binary.rs b/cli/standalone/binary.rs
index 9e2651226..960aad157 100644
--- a/cli/standalone/binary.rs
+++ b/cli/standalone/binary.rs
@@ -47,6 +47,7 @@ use deno_runtime::deno_fs::FileSystem;
 use deno_runtime::deno_fs::RealFs;
 use deno_runtime::deno_io::fs::FsError;
 use deno_runtime::deno_node::PackageJson;
+use deno_runtime::ops::otel::OtelConfig;
 use deno_semver::npm::NpmVersionReqParseError;
 use deno_semver::package::PackageReq;
 use deno_semver::Version;
@@ -185,6 +186,7 @@ pub struct Metadata {
   pub entrypoint_key: String,
   pub node_modules: Option<NodeModules>,
   pub unstable_config: UnstableConfig,
+  pub otel_config: Option<OtelConfig>, // None means disabled.
 }
 
 fn write_binary_bytes(
@@ -722,6 +724,7 @@ impl<'a> DenoCompileBinaryWriter<'a> {
         sloppy_imports: cli_options.unstable_sloppy_imports(),
         features: cli_options.unstable_features(),
       },
+      otel_config: cli_options.otel_config(),
     };
 
     write_binary_bytes(
diff --git a/cli/standalone/mod.rs b/cli/standalone/mod.rs
index 85610f4c2..bb0ab423d 100644
--- a/cli/standalone/mod.rs
+++ b/cli/standalone/mod.rs
@@ -800,6 +800,7 @@ pub async fn run(data: StandaloneData) -> Result<i32, AnyError> {
       serve_port: None,
       serve_host: None,
     },
+    metadata.otel_config,
   );
 
   // Initialize v8 once from the main thread.
diff --git a/cli/tsc/dts/lib.deno.unstable.d.ts b/cli/tsc/dts/lib.deno.unstable.d.ts
index 973a09d92..6234268c3 100644
--- a/cli/tsc/dts/lib.deno.unstable.d.ts
+++ b/cli/tsc/dts/lib.deno.unstable.d.ts
@@ -1225,6 +1225,108 @@ declare namespace Deno {
     export {}; // only export exports
   }
 
+  /**
+   * @category Telemetry
+   * @experimental
+   */
+  export namespace tracing {
+    /**
+     * Whether tracing is enabled.
+     * @category Telemetry
+     * @experimental
+     */
+    export const enabled: boolean;
+
+    /**
+     * Allowed attribute type.
+     * @category Telemetry
+     * @experimental
+     */
+    export type AttributeValue = string | number | boolean | bigint;
+
+    /**
+     * A tracing span.
+     * @category Telemetry
+     * @experimental
+     */
+    export class Span implements Disposable {
+      readonly traceId: string;
+      readonly spanId: string;
+      readonly parentSpanId: string;
+      readonly kind: string;
+      readonly name: string;
+      readonly startTime: number;
+      readonly endTime: number;
+      readonly status: null | { code: 1 } | { code: 2; message: string };
+      readonly attributes: Record<string, AttributeValue>;
+      readonly traceFlags: number;
+
+      /**
+       * Construct a new Span and enter it as the "current" span.
+       */
+      constructor(
+        name: string,
+        kind?: "internal" | "server" | "client" | "producer" | "consumer",
+      );
+
+      /**
+       * Set an attribute on this span.
+       */
+      setAttribute(
+        name: string,
+        value: AttributeValue,
+      ): void;
+
+      /**
+       * Enter this span as the "current" span.
+       */
+      enter(): void;
+
+      /**
+       * Exit this span as the "current" span and restore the previous one.
+       */
+      exit(): void;
+
+      /**
+       * End this span, and exit it as the "current" span.
+       */
+      end(): void;
+
+      [Symbol.dispose](): void;
+
+      /**
+       * Get the "current" span, if one exists.
+       */
+      static current(): Span | undefined | null;
+    }
+
+    /**
+     * A SpanExporter compatible with OpenTelemetry.js
+     * https://open-telemetry.github.io/opentelemetry-js/interfaces/_opentelemetry_sdk_trace_base.SpanExporter.html
+     * @category Telemetry
+     * @experimental
+     */
+    export class SpanExporter {}
+
+    /**
+     * A ContextManager compatible with OpenTelemetry.js
+     * https://open-telemetry.github.io/opentelemetry-js/interfaces/_opentelemetry_api.ContextManager.html
+     * @category Telemetry
+     * @experimental
+     */
+    export class ContextManager {}
+
+    export {}; // only export exports
+  }
+
+  /**
+   * @category Telemetry
+   * @experimental
+   */
+  export namespace metrics {
+    export {}; // only export exports
+  }
+
   export {}; // only export exports
 }
 
diff --git a/cli/worker.rs b/cli/worker.rs
index baacd681a..402644a42 100644
--- a/cli/worker.rs
+++ b/cli/worker.rs
@@ -30,6 +30,7 @@ use deno_runtime::deno_tls::RootCertStoreProvider;
 use deno_runtime::deno_web::BlobStore;
 use deno_runtime::fmt_errors::format_js_error;
 use deno_runtime::inspector_server::InspectorServer;
+use deno_runtime::ops::otel::OtelConfig;
 use deno_runtime::ops::process::NpmProcessStateProviderRc;
 use deno_runtime::ops::worker_host::CreateWebWorkerCb;
 use deno_runtime::web_worker::WebWorker;
@@ -142,6 +143,7 @@ struct SharedWorkerState {
   storage_key_resolver: StorageKeyResolver,
   options: CliMainWorkerOptions,
   subcommand: DenoSubcommand,
+  otel_config: Option<OtelConfig>, // `None` means OpenTelemetry is disabled.
 }
 
 impl SharedWorkerState {
@@ -405,6 +407,7 @@ impl CliMainWorkerFactory {
     storage_key_resolver: StorageKeyResolver,
     subcommand: DenoSubcommand,
     options: CliMainWorkerOptions,
+    otel_config: Option<OtelConfig>,
   ) -> Self {
     Self {
       shared: Arc::new(SharedWorkerState {
@@ -427,6 +430,7 @@ impl CliMainWorkerFactory {
         storage_key_resolver,
         options,
         subcommand,
+        otel_config,
       }),
     }
   }
@@ -576,6 +580,7 @@ impl CliMainWorkerFactory {
         mode,
         serve_port: shared.options.serve_port,
         serve_host: shared.options.serve_host.clone(),
+        otel_config: shared.otel_config.clone(),
       },
       extensions: custom_extensions,
       startup_snapshot: crate::js::deno_isolate_init(),
@@ -775,6 +780,7 @@ fn create_web_worker_callback(
         mode: WorkerExecutionMode::Worker,
         serve_port: shared.options.serve_port,
         serve_host: shared.options.serve_host.clone(),
+        otel_config: shared.otel_config.clone(),
       },
       extensions: vec![],
       startup_snapshot: crate::js::deno_isolate_init(),