feat(devex): cypress roulette

.github/workflows/ci-e2e.yml

@@ -14,7 +14,7 @@ concurrency:
 
 jobs:
     changes:
-        runs-on: ubuntu-24.04
+        runs-on: depot-ubuntu-24.04-4
         timeout-minutes: 5
         name: Determine need to run E2E checks
         # Set job outputs to values from filter step
@@ -40,6 +40,7 @@ jobs:
                         - package.json
                         - pnpm-lock.yaml
                         - .github/actions/build-n-cache-image/action.yml
+                        - .github/workflows/ci-e2e.yml
                         # We use docker compose for tests, make sure we rerun on
                         # changes to docker-compose.dev.yml e.g. dependency
                         # version changes
@@ -50,45 +51,49 @@ jobs:
     chunks:
         needs: changes
         name: Cypress preparation
-        runs-on: ubuntu-24.04
+        runs-on: depot-ubuntu-24.04-4
         timeout-minutes: 5
         outputs:
             chunks: ${{ steps.chunk.outputs.chunks }}
         steps:
             - name: Check out
               uses: actions/checkout@v3
 
-            - name: Group spec files into chunks of three
+            - name: Pick 4 random spec files
               id: chunk
               run: |
                   cd cypress
                   # Grab all .cy.ts files in e2e/
-                  files=$(ls e2e/*.cy.ts || true)
+                  files=$(ls e2e/*.cy.ts 2>/dev/null || true)
 
-                  # If no files exist, handle that gracefully:
+                  # If no files exist, handle that gracefully
                   if [ -z "$files" ]; then
                     echo "chunks=[]" >> "$GITHUB_OUTPUT"
                     exit 0
                   fi
 
-                  # 1. Chunk these filenames in groups of 2, then join each group with commas
-                  chunked=$(echo "$files" | xargs -n2 | sed 's/ /,/g')
+                  # Use the commit's SHA as a seeded random source. -n = no newline
+                  echo -n "cf73187282afdf3d7cd5e403ae1286955d7af992" | xxd -r -p > /tmp/random_source
 
-                  # 2. Convert each line into a JSON string, then produce a SINGLE-LINE JSON array
-                  #    Use `-c` for "compact" (no extra newlines).
-                  chunk_array=$(echo "$chunked" | jq -R . | jq -s -c .)
+                  # Shuffle (seeded by the random_source) and pick up to 4
+                  selected=$(echo "$files" | shuf --random-source=/tmp/random_source -n 4)
 
-                  # 3. Escape special characters for GitHub output:
+                  # We want a JSON array like ["testA.cy.ts","testB.cy.ts"]
+                  #   1. Each filename -> JSON string
+                  #   2. Collect into a JSON array
+                  chunk_array=$(echo "$selected" | jq -R . | jq -s -c .)
+
+                  # Escape % / newlines for GITHUB_OUTPUT
                   chunk_array="${chunk_array//'%'/'%25'}"
                   chunk_array="${chunk_array//$'\n'/'%0A'}"
                   chunk_array="${chunk_array//$'\r'/'%0D'}"
 
-                  # 4. Finally, write to GITHUB_OUTPUT in valid "key=value" form
+                  # Finally, store as 'chunks' output
                   echo "chunks=$chunk_array" >> "$GITHUB_OUTPUT"
 
     container:
         name: Build and cache container image
-        runs-on: ubuntu-24.04
+        runs-on: depot-ubuntu-24.04-4
         timeout-minutes: 60
         needs: [changes]
         permissions:
@@ -111,8 +116,8 @@ jobs:
                   actions-id-token-request-url: ${{ env.ACTIONS_ID_TOKEN_REQUEST_URL }}
 
     cypress:
-        name: Cypress E2E tests (${{ strategy.job-index }})
-        runs-on: ubuntu-24.04
+        name: Cypress E2E (${{ matrix.spec }})
+        runs-on: depot-ubuntu-24.04-4
         timeout-minutes: 60
         needs: [chunks, changes, container]
         permissions:
@@ -124,7 +129,7 @@ jobs:
             # we want to know about.
             fail-fast: false
             matrix:
-                chunk: ${{ fromJson(needs.chunks.outputs.chunks) }}
+                spec: ${{ fromJson(needs.chunks.outputs.chunks) }}
 
         steps:
             - name: Checkout
@@ -256,7 +261,7 @@ jobs:
               uses: cypress-io/github-action@v6
               with:
                   install-command: 'pnpm --filter=@posthog/cypress... install --frozen-lockfile'
-                  command: 'pnpm --filter=@posthog/cypress exec cypress run --config-file cypress.e2e.config.ts --spec ${{ matrix.chunk }} --headed'
+                  command: 'pnpm --filter=@posthog/cypress exec cypress run --config-file cypress.e2e.config.ts --spec ${{ matrix.spec }} --headed'
                   # We were seeing suprising crashes in headless mode
                   # See https://github.com/cypress-io/cypress/issues/28893#issuecomment-1956480875
               env:
@@ -267,43 +272,43 @@ jobs:
             - name: Archive test screenshots
               uses: actions/upload-artifact@v4
               with:
-                  name: screenshots-${{ strategy.job-index }}
+                  name: screenshots-${{ matrix.spec }}
                   path: cypress/screenshots
               if: ${{ failure() }}
 
             - name: Archive test downloads
               uses: actions/upload-artifact@v4
               with:
-                  name: downloads-${{ strategy.job-index }}
+                  name: downloads-${{ matrix.spec }}
                   path: cypress/downloads
               if: ${{ failure() }}
 
             - name: Archive test videos
               uses: actions/upload-artifact@v4
               with:
-                  name: videos-${{ strategy.job-index }}
+                  name: videos-${{ matrix.spec }}
                   path: cypress/videos
               if: ${{ failure() }}
 
             - name: Archive accessibility violations
               if: needs.changes.outputs.shouldTriggerCypress == 'true'
               uses: actions/upload-artifact@v4
               with:
-                  name: accessibility-violations-${{ strategy.job-index }}
+                  name: accessibility-violations-${{ matrix.spec }}
                   path: '**/a11y/'
                   if-no-files-found: 'ignore'
 
             - name: Show logs on failure
               # use artefact here, as I think the output will be too large for display in an action
               uses: actions/upload-artifact@v4
               with:
-                  name: logs-${{ strategy.job-index }}
+                  name: logs-${{ matrix.spec }}
                   path: /tmp/logs
               if: ${{ failure() }}
 
     calculate-running-time:
         name: Calculate running time
-        runs-on: ubuntu-24.04
+        runs-on: depot-ubuntu-24.04-4
         needs: [cypress]
         if: needs.changes.outputs.shouldTriggerCypress == 'true' &&
             github.event.pull_request.head.repo.full_name == 'PostHog/posthog'