Add GitHub workflow to combine dependabot PRs

Signed-off-by: Jérôme Benoit <jerome.benoit@sap.com>

diff --git a/.github/workflows/combine-prs.yml b/.github/workflows/combine-prs.yml
new file mode 100644 (file)
index 0000000..41b21be
--- /dev/null
+++ b/.github/workflows/combine-prs.yml
@@ -0,0 +1,134 @@
+name: 'Combine PRs'
+
+# Controls when the action will run - in this case triggered manually
+on:
+  workflow_dispatch:
+    inputs:
+      branchPrefix:
+        description: 'Branch prefix to find combinable PRs based on'
+        required: true
+        default: 'dependabot'
+      mustBeGreen:
+        description: 'Only combine PRs that are green (status is success)'
+        required: true
+        default: true
+      combineBranchName:
+        description: 'Name of the branch to combine PRs into'
+        required: true
+        default: 'combine-prs-branch'
+      ignoreLabel:
+        description: 'Exclude PRs with this label'
+        required: true
+        default: 'nocombine'
+
+# A workflow run is made up of one or more jobs that can run sequentially or in parallel
+jobs:
+  # This workflow contains a single job called "combine-prs"
+  combine-prs:
+    # The type of runner that the job will run on
+    runs-on: ubuntu-latest
+
+    # Steps represent a sequence of tasks that will be executed as part of the job
+    steps:
+      - uses: actions/github-script@v6
+        id: create-combined-pr
+        name: Create Combined PR
+        with:
+          github-token: ${{secrets.GITHUB_TOKEN}}
+          script: |
+            const pulls = await github.paginate('GET /repos/:owner/:repo/pulls', {
+              owner: context.repo.owner,
+              repo: context.repo.repo
+            });
+            let branchesAndPRStrings = [];
+            let baseBranch = null;
+            let baseBranchSHA = null;
+            for (const pull of pulls) {
+              const branch = pull['head']['ref'];
+              console.log('Pull for branch: ' + branch);
+              if (branch.startsWith('${{ github.event.inputs.branchPrefix }}')) {
+                console.log('Branch matched prefix: ' + branch);
+                let statusOK = true;
+                if(${{ github.event.inputs.mustBeGreen }}) {
+                  console.log('Checking green status: ' + branch);
+                  const statusResponse = await github.rest.repos.getCombinedStatusForRef({
+                    owner: context.repo.owner,
+                    repo: context.repo.repo,
+                    ref: branch
+                  });
+                  const state = statusResponse['data']['state'];
+                  console.log('Validating status: ' + state);
+                  if(state != 'success') {
+                    console.log('Discarding ' + branch + ' with status ' + state);
+                    statusOK = false;
+                  }
+                }
+                console.log('Checking labels: ' + branch);
+                const labels = pull['labels'];
+                for(const label of labels) {
+                  const labelName = label['name'];
+                  console.log('Checking label: ' + labelName);
+                  if(labelName == '${{ github.event.inputs.ignoreLabel }}') {
+                    console.log('Discarding ' + branch + ' with label ' + labelName);
+                    statusOK = false;
+                  }
+                }
+                if (statusOK) {
+                  console.log('Adding branch to array: ' + branch);
+                  const prString = '#' + pull['number'] + ' ' + pull['title'];
+                  branchesAndPRStrings.push({ branch, prString });
+                  baseBranch = pull['base']['ref'];
+                  baseBranchSHA = pull['base']['sha'];
+                }
+              }
+            }
+            if (branchesAndPRStrings.length == 0) {
+              core.setFailed('No PRs/branches matched criteria');
+              return;
+            }
+            try {
+              await github.rest.git.createRef({
+                owner: context.repo.owner,
+                repo: context.repo.repo,
+                ref: 'refs/heads/' + '${{ github.event.inputs.combineBranchName }}',
+                sha: baseBranchSHA
+              });
+            } catch (error) {
+              console.log(error);
+              core.setFailed('Failed to create combined branch - maybe a branch by that name already exists?');
+              return;
+            }
+
+            let combinedPRs = [];
+            let mergeFailedPRs = [];
+            for(const { branch, prString } of branchesAndPRStrings) {
+              try {
+                await github.rest.repos.merge({
+                  owner: context.repo.owner,
+                  repo: context.repo.repo,
+                  base: '${{ github.event.inputs.combineBranchName }}',
+                  head: branch,
+                });
+                console.log('Merged branch ' + branch);
+                combinedPRs.push(prString);
+              } catch (error) {
+                console.log('Failed to merge branch ' + branch);
+                mergeFailedPRs.push(prString);
+              }
+            }
+
+            console.log('Creating combined PR');
+            const combinedPRsString = combinedPRs.join('\n');
+            let body = '✅ This PR was created by the Combine PRs action by combining the following PRs:\n' + combinedPRsString;
+            if(mergeFailedPRs.length > 0) {
+              const mergeFailedPRsString = mergeFailedPRs.join('\n');
+              body += '\n\n⚠️ The following PRs were left out due to merge conflicts:\n' + mergeFailedPRsString
+            }
+            await github.rest.pulls.create({
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+              title: 'Combined PR',
+              head: '${{ github.event.inputs.combineBranchName }}',
+              base: baseBranch,
+              body: body
+            });