chore(ci): automatically open PR to forward patch release back to main (#14180)

4 files changed, 103 insertions, 22 deletions

diff --git a/.github/workflows/cargo_publish.yml b/.github/workflows/cargo_publish.yml
index 29eee22fa..4bb2ad686 100644
--- a/.github/workflows/cargo_publish.yml
+++ b/.github/workflows/cargo_publish.yml
@@ -36,7 +36,11 @@ jobs:
           CARGO_REGISTRY_TOKEN: ${{ secrets.CARGO_REGISTRY_TOKEN }}
         run: ./tools/release/03_publish_crates.ts --real
 
-      - name: Create release tag
+      - name: Create release tag and check forward commit to main
         env:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
-        run: ./tools/release/04_create_release_tag.ts
+          GH_WORKFLOW_ACTOR: ${{ github.actor }}
+        run: |
+          git config user.email "${{ github.actor }}@users.noreply.github.com"
+          git config user.name "${{ github.actor }}"
+          ./tools/release/04_post_publish.ts
diff --git a/tools/cut_a_release.md b/tools/cut_a_release.md
index 499642e0e..3969793c6 100644
--- a/tools/cut_a_release.md
+++ b/tools/cut_a_release.md
@@ -112,8 +112,9 @@ verify on GitHub that everything looks correct.
    been updated to reflect Web API changes in this release. Usually done ahead
    of time by @lucacasonato.
 
-9. **If you are cutting a patch release**: open a PR that forwards all commits
-   created in the release process to the `main` branch.
+9. **If you are cutting a patch release**: a PR should have been automatically
+   opened that forwards the release commit back to main. If so, merge it. If not
+   and it failed, please manually create one.
 
 ## Updating `doc.deno.land`
 
diff --git a/tools/release/04_create_release_tag.ts b/tools/release/04_create_release_tag.ts
deleted file mode 100755
index 8eaac2514..000000000
--- a/tools/release/04_create_release_tag.ts
+++ /dev/null
@@ -1,18 +0,0 @@
-#!/usr/bin/env -S deno run --allow-read --allow-write --allow-run=cargo,git --no-check
-// Copyright 2018-2022 the Deno authors. All rights reserved. MIT license.
-import { DenoWorkspace } from "./deno_workspace.ts";
-
-const workspace = await DenoWorkspace.load();
-const repo = workspace.repo;
-const cliCrate = workspace.getCliCrate();
-
-await repo.gitFetchTags("origin");
-const tags = await repo.getGitTags();
-const tagName = `v${cliCrate.version}`;
-
-if (tags.has(tagName)) {
-  console.log(`Tag ${tagName} already exists.`);
-} else {
-  await repo.gitTag(tagName);
-  await repo.gitPush(tagName);
-}
diff --git a/tools/release/04_post_publish.ts b/tools/release/04_post_publish.ts
new file mode 100755
index 000000000..d437bb39a
--- /dev/null
+++ b/tools/release/04_post_publish.ts
@@ -0,0 +1,94 @@
+#!/usr/bin/env -S deno run --allow-read --allow-write --allow-run=cargo,git --allow-net --no-check
+// Copyright 2018-2022 the Deno authors. All rights reserved. MIT license.
+import { DenoWorkspace } from "./deno_workspace.ts";
+import { createOctoKit, getGitHubRepository } from "./deps.ts";
+
+const workspace = await DenoWorkspace.load();
+const repo = workspace.repo;
+const cliCrate = workspace.getCliCrate();
+
+console.log("Creating release tag...");
+await createReleaseTag();
+
+console.log("Forwarding release commit to main...");
+try {
+  await forwardReleaseCommitToMain();
+} catch (err) {
+  console.error("Failed. Please manually open a PR.", err);
+}
+
+async function createReleaseTag() {
+  await repo.gitFetchTags("origin");
+  const tags = await repo.getGitTags();
+  const tagName = `v${cliCrate.version}`;
+
+  if (tags.has(tagName)) {
+    console.log(`Tag ${tagName} already exists.`);
+  } else {
+    await repo.gitTag(tagName);
+    await repo.gitPush(tagName);
+  }
+}
+
+async function forwardReleaseCommitToMain() {
+  // if this is a patch release, open a PR to forward the most recent commit back to main
+  const currentBranch = await repo.gitCurrentBranch();
+  const isPatchRelease = currentBranch !== "main";
+
+  if (!isPatchRelease) {
+    console.log("Not doing a patch release. Skipping.");
+    return;
+  }
+
+  const releaseCommitHash =
+    (await repo.runCommand(["git", "rev-parse", "HEAD"])).trim();
+  const newBranchName = `forward_v${cliCrate.version}`;
+  console.log(`Creating branch ${newBranchName}...`);
+  await repo.runCommand([
+    "git",
+    "checkout",
+    "-b",
+    newBranchName,
+    "main",
+  ]);
+  await repo.runCommand([
+    "git",
+    "cherry-pick",
+    releaseCommitHash,
+  ]);
+  await repo.gitPush("origin", newBranchName);
+
+  console.log(`Opening PR...`);
+  const openedPr = await createOctoKit().request(
+    "POST /repos/{owner}/{repo}/pulls",
+    {
+      ...getGitHubRepository(),
+      base: "main",
+      head: newBranchName,
+      draft: true,
+      title: `chore: forward v${cliCrate.version} release commit to main`,
+      body: getPrBody(),
+    },
+  );
+  console.log(`Opened PR at ${openedPr.data.url}`);
+
+  function getPrBody() {
+    let text =
+      `This is the release commit being forwarded back to main for ${cliCrate.version}\n\n` +
+      `Please ensure:\n` +
+      `- [ ] Everything looks ok in the PR\n` +
+      `- [ ] The release has been published\n\n` +
+      `To make edits to this PR:\n` +
+      "```shell\n" +
+      `git fetch upstream ${newBranchName} && git checkout -b ${newBranchName} upstream/${newBranchName}\n` +
+      "```\n\n" +
+      "Don't need this PR? Close it.\n";
+
+    const actor = Deno.env.get("GH_WORKFLOW_ACTOR");
+    if (actor != null) {
+      text += `\ncc @${actor}`;
+    }
+
+    return text;
+  }
+}