benchmark-pr.yml

name: Benchmark PR

on:
  pull_request:
    types: [opened, synchronize, reopened]
    paths:
      - "apps/api/**"
      - "benchmarks/**"

permissions:
  contents: read
  pull-requests: write
  issues: write

jobs:
  benchmark-pr:
    runs-on: ubuntu-latest
    timeout-minutes: 15

    steps:
      - name: Checkout PR branch
        uses: actions/checkout@v4
        with:
          ref: ${{ github.event.pull_request.head.sha }}

      - name: Setup Node.js
        uses: actions/setup-node@v4
        with:
          node-version: "22"

      - name: Install dependencies
        run: npm ci --workspace=apps/api 2>/dev/null || npm install --workspace=apps/api

      - name: Start API (PR branch)
        run: |
          NODE_ENV=production PORT=4001 JWT_SECRET=ci-pr-secret \
            node apps/api/src/server.js &
          for i in $(seq 1 30); do
            if curl -s http://localhost:4001/health | grep -q '"ok":true'; then
              echo "✅ PR API ready"
              exit 0
            fi
            sleep 1
          done
          exit 1

      - name: Run benchmark (PR branch)
        run: |
          npx k6 run \
            --summary-export=benchmarks/results/pr-summary.json \
            benchmarks/k6/load-test.js 2>&1 | tee benchmarks/results/pr-console.log
        env:
          BASE_URL: http://localhost:4001

      - name: Checkout main for baseline
        run: |
          git fetch origin main:main-ref 2>/dev/null || true
          if git show-ref --verify --quiet refs/heads/main-ref; then
            git checkout main-ref -- apps/api/ benchmarks/k6/ || true
          fi

      - name: Start API (main branch)
        run: |
          NODE_ENV=production PORT=4002 JWT_SECRET=ci-main-secret \
            node apps/api/src/server.js &
          for i in $(seq 1 30); do
            if curl -s http://localhost:4002/health | grep -q '"ok":true'; then
              echo "✅ Main API ready"
              exit 0
            fi
            sleep 1
          done
          exit 1

      - name: Run benchmark (main branch)
        run: |
          npx k6 run \
            --summary-export=benchmarks/results/main-summary.json \
            benchmarks/k6/load-test.js 2>&1 | tee benchmarks/results/main-console.log
        env:
          BASE_URL: http://localhost:4002

      - name: Compute diff
        id: diff
        run: |
          # Extract key metrics from both runs
          PR_P95=$(jq -r '.http_req_duration.p95 // "0"' benchmarks/results/pr-summary.json)
          MAIN_P95=$(jq -r '.http_req_duration.p95 // "0"' benchmarks/results/main-summary.json)
          PR_P99=$(jq -r '.http_req_duration.p99 // "0"' benchmarks/results/pr-summary.json)
          MAIN_P99=$(jq -r '.http_req_duration.p99 // "0"' benchmarks/results/main-summary.json)
          PR_AVG=$(jq -r '.http_req_duration.avg // "0"' benchmarks/results/pr-summary.json)
          MAIN_AVG=$(jq -r '.http_req_duration.avg // "0"' benchmarks/results/main-summary.json)
          PR_RPS=$(jq -r '.http_reqs.rate // "0"' benchmarks/results/pr-summary.json)
          MAIN_RPS=$(jq -r '.http_reqs.rate // "0"' benchmarks/results/main-summary.json)
          PR_ERR=$(jq -r '.http_req_failed.rate // "0%"' benchmarks/results/pr-summary.json)
          MAIN_ERR=$(jq -r '.http_req_failed.rate // "0%"' benchmarks/results/main-summary.json)

          # Compute deltas
          DELTA_P95=$(awk "BEGIN {printf \"%.1f\", ($PR_P95 - $MAIN_P95)}")
          DELTA_P99=$(awk "BEGIN {printf \"%.1f\", ($PR_P99 - $MAIN_P99)}")
          DELTA_AVG=$(awk "BEGIN {printf \"%.1f\", ($PR_AVG - $MAIN_AVG)}")
          DELTA_RPS=$(awk "BEGIN {printf \"%.1f\", ($PR_RPS - $MAIN_RPS)}")

          # Determine severity
          if (( $(echo "$DELTA_P95 > 50" | bc -l) )); then
            SEVERITY="⚠️"
          elif (( $(echo "$DELTA_P95 > 20" | bc -l) )); then
            SEVERITY="👀"
          else
            SEVERITY="✅"
          fi

          # Generate markdown comment
          cat > /tmp/benchmark-comment.md << 'HEREDOC'
          ## 📊 API Benchmark Results

          | Metric | Main (`base`) | This PR | Delta |
          |--------|:------------:|:-------:|:-----:|
          | **Avg Latency** | MAIN_AVG ms | PR_AVG ms | DELTA_AVG ms |
          | **p95 Latency** | MAIN_P95 ms | PR_P95 ms | DELTA_P95 ms |
          | **p99 Latency** | MAIN_P99 ms | PR_P99 ms | DELTA_P99 ms |
          | **RPS** | MAIN_RPS/s | PR_RPS/s | DELTA_RPS/s |
          | **Error Rate** | MAIN_ERR | PR_ERR | — |

          SEVERITY **Verdict:** DELTA_VERDICT

          ---
          <details>
          <summary>📋 Full benchmark details</summary>

          ### PR Branch
          ```
          $(cat benchmarks/results/pr-console.log | tail -30)
          ```

          ### Main Branch
          ```
          $(cat benchmarks/results/main-console.log | tail -30)
          ```
          </details>

          <sub>⚡ Benchmarks run with k6 • 50 VUs • 60s duration</sub>
          HEREDOC

          # Substitute placeholders
          sed -i "s/MAIN_AVG/$MAIN_AVG/g; s/PR_AVG/$PR_AVG/g; s/DELTA_AVG/${DELTA_AVG}/g" /tmp/benchmark-comment.md
          sed -i "s/MAIN_P95/$MAIN_P95/g; s/PR_P95/$PR_P95/g; s/DELTA_P95/${DELTA_P95}/g" /tmp/benchmark-comment.md
          sed -i "s/MAIN_P99/$MAIN_P99/g; s/PR_P99/$PR_P99/g; s/DELTA_P99/${DELTA_P99}/g" /tmp/benchmark-comment.md
          sed -i "s/MAIN_RPS/$MAIN_RPS/g; s/PR_RPS/$PR_RPS/g; s/DELTA_RPS/${DELTA_RPS}/g" /tmp/benchmark-comment.md
          sed -i "s|MAIN_ERR|$MAIN_ERR|g; s|PR_ERR|$PR_ERR|g" /tmp/benchmark-comment.md
          sed -i "s/SEVERITY/$SEVERITY/g" /tmp/benchmark-comment.md

          if [ "$SEVERITY" = "✅" ]; then
            DELTA_VERDICT="No significant performance regression detected."
          elif [ "$SEVERITY" = "👀" ]; then
            DELTA_VERDICT="Minor latency increase — worth reviewing but not blocking."
          else
            DELTA_VERDICT="⚠️ Significant p95 latency increase (+${DELTA_P95}ms) — investigate before merging."
          fi
          sed -i "s/DELTA_VERDICT/$DELTA_VERDICT/" /tmp/benchmark-comment.md

          cat /tmp/benchmark-comment.md

      - name: Post PR comment
        uses: actions/github-script@v7
        with:
          script: |
            const fs = require('fs');
            const body = fs.readFileSync('/tmp/benchmark-comment.md', 'utf8');

            // Find existing benchmark comment
            const { data: comments } = await github.rest.issues.listComments({
              owner: context.repo.owner,
              repo: context.repo.repo,
              issue_number: context.issue.number,
            });

            const existing = comments.find(c =>
              c.body.includes('API Benchmark Results') &&
              c.user.login === 'github-actions[bot]'
            );

            if (existing) {
              await github.rest.issues.updateComment({
                owner: context.repo.owner,
                repo: context.repo.repo,
                comment_id: existing.id,
                body,
              });
            } else {
              await github.rest.issues.createComment({
                owner: context.repo.owner,
                repo: context.repo.repo,
                issue_number: context.issue.number,
                body,
              });
            }