feat: automatic dependabot pr changesets

.github/scripts/dependabot-changeset.js

@@ -0,0 +1,113 @@
+/**
+ * Creates a changeset file for Dependabot PRs that update production
+ * dependencies in published @knocklabs/* packages.
+ *
+ * Skips devDependency-only changes since those don't require a release.
+ *
+ * This script is only run from a workflow gated to dependabot[bot],
+ * so we trust that the changes are dependency updates.
+ *
+ * Environment variables:
+ *   PR_TITLE      - The pull request title (used as the changeset description)
+ *   PR_NUMBER     - The pull request number (used in the changeset filename)
+ *   GITHUB_OUTPUT - Path to the GitHub Actions output file
+ */
+
+const { execSync } = require("child_process");
+const fs = require("fs");
+const path = require("path");
+
+const prTitle = process.env.PR_TITLE;
+const prNumber = process.env.PR_NUMBER;
+const githubOutput = process.env.GITHUB_OUTPUT;
+
+if (!prTitle || !prNumber || !githubOutput) {
+  console.error(
+    "Missing required environment variables: PR_TITLE, PR_NUMBER, GITHUB_OUTPUT",
+  );
+  process.exit(1);
+}
+
+const changesetFile = path.join(".changeset", `dependabot-pr-${prNumber}.md`);
+
+function setOutput(key, value) {
+  fs.appendFileSync(githubOutput, `${key}=${value}\n`);
+}
+
+// If changeset already exists, skip
+if (fs.existsSync(changesetFile)) {
+  console.log("Changeset already exists, skipping");
+  setOutput("created", "false");
+  process.exit(0);
+}
+
+// Find all package.json files changed in the latest commit
+const diffOutput = execSync(
+  "git diff --name-only HEAD~1 HEAD -- '**/package.json'",
+  { encoding: "utf-8" },
+).trim();
+
+if (!diffOutput) {
+  console.log("No package.json files changed");
+  setOutput("created", "false");
+  process.exit(0);
+}
+
+const changedFiles = diffOutput.split("\n").filter(Boolean);
+const packages = [];
+
+for (const pkgFile of changedFiles) {
+  const content = JSON.parse(fs.readFileSync(pkgFile, "utf-8"));
+  const pkgName = content.name || "";
+
+  if (content.private || !pkgName.startsWith("@knocklabs/")) {
+    continue;
+  }
+
+  // Only include packages where production dependencies changed,
+  // not devDependency-only updates
+  let oldDeps = {};
+  try {
+    const oldContent = execSync(`git show "HEAD~1:${pkgFile}"`, {
+      encoding: "utf-8",
+    });
+    oldDeps = JSON.parse(oldContent).dependencies || {};
+  } catch {
+    // File may not exist in previous commit
+  }
+
+  const newDeps = content.dependencies || {};
+  const sortedOld = JSON.stringify(oldDeps, Object.keys(oldDeps).sort());
+  const sortedNew = JSON.stringify(newDeps, Object.keys(newDeps).sort());
+
+  if (sortedOld === sortedNew) {
+    console.log(`Only devDependency changes in ${pkgName}, skipping`);
+    continue;
+  }
+
+  packages.push(pkgName);
+}
+
+const uniquePackages = [...new Set(packages)].sort();
+
+if (uniquePackages.length === 0) {
+  console.log("No published @knocklabs packages were affected");
+  setOutput("created", "false");
+  process.exit(0);
+}
+
+// Generate changeset file
+const lines = [
+  "---",
+  ...uniquePackages.map((pkg) => `"${pkg}": patch`),
+  "---",
+  "",
+  prTitle,
+  "",
+];
+
+fs.writeFileSync(changesetFile, lines.join("\n"));
+
+console.log(`Created changeset: ${changesetFile}`);
+console.log(fs.readFileSync(changesetFile, "utf-8"));
+setOutput("created", "true");

.github/workflows/dependabot-changeset.yml

@@ -0,0 +1,77 @@
+name: Dependabot Changeset
+
+on:
+  pull_request_target:
+    types: [opened]
+  workflow_dispatch:
+    inputs:
+      pr-number:
+        description: "Pull request number to add a changeset for"
+        required: true
+        type: string
+
+jobs:
+  changeset:
+    name: Add changeset for dependency update
+    runs-on: ubuntu-latest
+    if: github.actor == 'dependabot[bot]' || github.event_name == 'workflow_dispatch'
+
+    steps:
+      - name: Get PR metadata
+        id: pr
+        env:
+          GH_TOKEN: ${{ secrets.KNOCK_ENG_BOT_GITHUB_TOKEN }}
+          EVENT_NAME: ${{ github.event_name }}
+          INPUT_PR_NUMBER: ${{ inputs.pr-number }}
+          REPO: ${{ github.repository }}
+          PR_NUMBER_FROM_EVENT: ${{ github.event.pull_request.number }}
+          PR_TITLE_FROM_EVENT: ${{ github.event.pull_request.title }}
+          PR_REF_FROM_EVENT: ${{ github.event.pull_request.head.ref }}
+        run: |
+          if [ "$EVENT_NAME" = "workflow_dispatch" ]; then
+            PR_JSON=$(gh pr view "$INPUT_PR_NUMBER" --repo "$REPO" --json title,headRefName)
+            echo "number=$INPUT_PR_NUMBER" >> "$GITHUB_OUTPUT"
+            echo "title=$(echo "$PR_JSON" | jq -r '.title')" >> "$GITHUB_OUTPUT"
+            echo "ref=$(echo "$PR_JSON" | jq -r '.headRefName')" >> "$GITHUB_OUTPUT"
+          else
+            echo "number=$PR_NUMBER_FROM_EVENT" >> "$GITHUB_OUTPUT"
+            echo "title=$PR_TITLE_FROM_EVENT" >> "$GITHUB_OUTPUT"
+            echo "ref=$PR_REF_FROM_EVENT" >> "$GITHUB_OUTPUT"
+          fi
+
+      # Checkout the base branch to get the trusted version of the script,
+      # then checkout the PR branch on top to get the package.json changes.
+      - name: Checkout base branch
+        uses: actions/checkout@v4
+        with:
+          ref: main
+          token: ${{ secrets.KNOCK_ENG_BOT_GITHUB_TOKEN }}
+          path: base
+
+      - name: Checkout PR branch
+        uses: actions/checkout@v4
+        with:
+          ref: ${{ steps.pr.outputs.ref }}
+          token: ${{ secrets.KNOCK_ENG_BOT_GITHUB_TOKEN }}
+          fetch-depth: 2
+
+      - name: Setup Node.js
+        uses: actions/setup-node@v4
+        with:
+          node-version-file: "package.json"
+
+      - name: Detect affected packages and create changeset
+        id: changeset
+        env:
+          PR_TITLE: ${{ steps.pr.outputs.title }}
+          PR_NUMBER: ${{ steps.pr.outputs.number }}
+        run: node base/.github/scripts/dependabot-changeset.js
+
+      - name: Commit and push changeset
+        if: steps.changeset.outputs.created == 'true'
+        run: |
+          git config user.name "knock-eng-bot"
+          git config user.email "knock-eng-bot@users.noreply.github.com"
+          git add .changeset/
+          git commit -m "chore(deps): add changeset for dependency update"
+          git push