check-pull-request-size.yaml

name: Check pull request size
on:
  pull_request:
    types: [opened, reopened, edited, ready_for_review, labeled, unlabeled, synchronize]
    branches:
      - master
      - "release/v*"

concurrency:
  group: ${{ github.workflow }}-${{ github.ref }}
  cancel-in-progress: true

jobs:
  check_pull_request_size:
    name: Check pull request size
    # Skip draft pull requests
    if: ${{ !github.event.pull_request.draft }}
    permissions:
      contents: read # Required to check out the pull request changes
      id-token: write # Required for OIDC token federation
    runs-on: ubuntu-latest
    steps:
      - name: Checkout pull request changes
        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # 7.0.1
        with:
          fetch-depth: 2 # Fetch the pull request merge commit and its parents
          filter: blob:none
          sparse-checkout: .github # Only the git history is needed, keep the working tree small
          persist-credentials: false
      - name: Count added lines
        id: count-added-lines
        run: |
          set -euo pipefail
          # Count the added lines, excluding moved lines, test code and resources, and lock files.
          # Moved lines (blocks of at least 20 alphanumeric characters deleted and added elsewhere, even
          # re-indented or in another file) are told apart from added lines using diff colors:
          # added lines are painted green and moved lines blue, then only the green lines are counted.
          # The first parent of the pull request merge commit is the base branch.
          ADDED_LINES=$(git \
            -c color.diff.meta=bold \
            -c color.diff.new=green \
            -c color.diff.newMoved=blue \
            diff \
            --color=always \
            --color-moved=blocks \
            --color-moved-ws=allow-indentation-change \
            --ws-error-highlight=none \
            --find-renames \
            --no-ext-diff \
            HEAD^1 HEAD \
            -- . \
            ':(exclude,glob)**/src/test*/**' \
            ':(exclude,glob)**/src/*Test*/**' \
            ':(exclude,glob)**/gradle.lockfile' |
            awk '/^\033\[32m\+/ { count++ } END { print count + 0 }')
          echo "Added lines: $ADDED_LINES"
          echo "added_lines=$ADDED_LINES" >> "$GITHUB_OUTPUT"
      - name: Get GitHub Token via dd-octo-sts
        id: generate-token
        uses: DataDog/dd-octo-sts-action@c85802a58e202b7e764b5441e4378c76043c8108 # v1.0.5
        with:
          scope: DataDog/dd-trace-java
          policy: self.check-pull-request-size
      - name: Check pull request size
        uses: actions/github-script@3a2844b7e9c422d3c10d287c895573f7108da1b3 # 9.0.0
        env:
          ADDED_LINES: ${{ steps.count-added-lines.outputs.added_lines }}
          MAX_ADDED_LINES: 1000
        with:
          github-token: ${{ steps.generate-token.outputs.token }}
          script: |
            const managedMarker = '<!-- dd-trace-java-check-pull-request-size -->'
            const overrideLabel = 'tag: override pr size check'
            const addedLines = parseInt(process.env.ADDED_LINES, 10)
            const maxAddedLines = parseInt(process.env.MAX_ADDED_LINES, 10)

            // Look for the previous managed comment
            const comments = await github.paginate(github.rest.issues.listComments, {
              issue_number: context.payload.pull_request.number,
              owner: context.repo.owner,
              repo: context.repo.repo
            })
            const existingComment = comments.find(comment => comment.body?.includes(managedMarker))

            const deleteManagedComment = async () => {
              if (existingComment) {
                await github.rest.issues.deleteComment({
                  comment_id: existingComment.id,
                  owner: context.repo.owner,
                  repo: context.repo.repo
                })
              }
            }

            // Check for override label — skip the check if label present
            const labels = context.payload.pull_request.labels.map(l => l.name)
            if (labels.includes(overrideLabel)) {
              await deleteManagedComment()
              console.log(`${overrideLabel} label detected — skipping the check.`)
              return
            }

            if (addedLines < maxAddedLines) {
              await deleteManagedComment()
              console.log(`Pull request adds ${addedLines} lines, below the ${maxAddedLines} lines limit.`)
              return
            }

            const body = `**❌ Pull Request Too Large**\n\n` +
              `This pull request adds **${addedLines}** lines while the limit is **${maxAddedLines}** lines.\n` +
              `Deleted lines, moved code, test code and resources (\`src/test\`, \`src/testFixtures\`, \`src/latestDepTest\`, and other test source sets), and \`gradle.lockfile\` files are not counted.\n\n` +
              `Please split it into smaller stacked pull requests, each one targeting the branch of the previous one. ` +
              `See the [pull request size guidelines](https://github.com/DataDog/dd-trace-java/blob/master/CONTRIBUTING.md#pull-request-size) for more details.\n\n` +
              `If this PR cannot be split, exceptionnaly add the \`${overrideLabel}\` label to bypass this workflow.\n\n` +
              managedMarker
            if (existingComment) {
              await github.rest.issues.updateComment({
                comment_id: existingComment.id,
                owner: context.repo.owner,
                repo: context.repo.repo,
                body
              })
            } else {
              await github.rest.issues.createComment({
                issue_number: context.payload.pull_request.number,
                owner: context.repo.owner,
                repo: context.repo.repo,
                body
              })
            }
            core.setFailed(`Pull request adds ${addedLines} lines, above the ${maxAddedLines} lines limit. See PR comment for details. To bypass this workflow, add the '${overrideLabel}' label.`)