chore: workflow to update the list of regions for AWS::CDK::Metadata (

#27981)

Steps:

1. Get the list of regions from our single source of truth.
2. Convert that list into the TypeScript code that should be the content of `packages/aws-cdk-lib/region-info/build-tools/metadata.ts`.
3. Create a PR if there were any changes.

The workflow is triggered every day at 00:00.

----

*By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license*

.github/workflows/update-metadata-regions.yml

@@ -0,0 +1,78 @@
+name: Update Metadata Regions
+on:
+  workflow_dispatch:
+  schedule:
+    - cron: "0 0 * * *"
+
+jobs:
+  update-regions:
+    name: Update Regions
+    runs-on: ubuntu-latest
+    steps:
+      - name: Download regions
+        env:
+          URL: https://d3mqmgkwnwa8vm.cloudfront.net/regions.json
+        id: download
+        run: |
+          response=$(curl $URL)
+          echo "REGIONS=${response}" >> "$GITHUB_OUTPUT"
+          
+          status=$(curl -s -o /dev/null -w "%{http_code}" $URL)
+          echo "STATUS=${status}" >> "$GITHUB_OUTPUT"
+      - uses: actions/checkout@v3
+      - uses: actions/github-script@v7
+        if: ${{ steps.download.outputs.STATUS == 200 }}
+        env:
+          REGIONS: ${{ steps.download.outputs.REGIONS }}
+        with:
+          script: |
+            const script = require('./scripts/update-metadata-regions.js')
+            script()
+      - name: Create Patch
+        run: |-
+          git add .
+          git diff --patch --staged > ${{ runner.temp }}/update-spec.patch
+      - name: Upload Patch
+        uses: actions/upload-artifact@v3
+        with:
+          name: update-spec.patch
+          path: ${{ runner.temp }}/update-spec.patch
+
+  pr:
+    name: Create Pull Request
+    needs: update-regions
+    permissions:
+      contents: write
+      pull-requests: write
+    runs-on: ubuntu-latest
+    steps:
+      - name: Check Out
+        uses: actions/checkout@v4
+
+      - name: Download patch
+        uses: actions/download-artifact@v3
+        with:
+          name: update-spec.patch
+          path: ${{ runner.temp }}
+
+      - name: Apply patch
+        run: '[ -s ${{ runner.temp }}/update-spec.patch ] && git apply ${{ runner.temp }}/update-spec.patch || echo "Empty patch. Skipping."'
+
+      - name: Make Pull Request
+        uses: peter-evans/create-pull-request@v5
+        with:
+          # Git commit details
+          branch: automation/region-update
+          author: aws-cdk-automation <aws-cdk-automation@users.noreply.github.com>
+          commit-message: |-
+            feat(region-info): update Metadata regions
+            Update the list of regions where the CDK deploys the `AWS::CDK::Metadata` resource.
+          # Pull Request details
+          title: "feat(region-info): update Metadata regions"
+          body: |-
+            Update the list of regions where the CDK deploys the `AWS::CDK::Metadata` resource.
+          labels: contribution/core,dependencies,auto-approve,pr-linter/exempt-integ-test,pr-linter/exempt-readme,pr-linter/exempt-test
+          team-reviewers: aws-cdk-team
+          # Github prevents further Github actions to be run if the default Github token is used.
+          # Instead use a privileged token here, so further GH actions can be triggered on this PR.
+          token: ${{ secrets.PROJEN_GITHUB_TOKEN }}

scripts/update-metadata-regions.js

@@ -0,0 +1,26 @@
+module.exports = () => {
+    const fs= require('fs');
+    const regions = JSON.parse(process.env.REGIONS);
+    const content = generateFileContent(regions);
+    const path = './packages/aws-cdk-lib/region-info/build-tools/metadata.ts';
+    fs.writeFileSync(path, content);
+}
+
+function generateFileContent(regions) {
+    const template = `/*
+* Do not edit this file manually. To prevent misconfiguration, this file
+* should only be modified by an automated GitHub workflow, that ensures
+* that the regions present in this list correspond to all the regions
+* where we have the AWS::CDK::Metadata handler deployed.
+*
+* See: https://github.com/aws/aws-cdk/issues/27189
+*/
+
+export const AWS_CDK_METADATA = new Set([
+$REGIONS
+]);
+`;
+
+    const list = regions.sort().map(r => `  '${r}',`).join('\n');
+    return template.replace('$REGIONS', list);
+}