Warum Flutter iOS CI auf einem Cloud Mac langsamer wird: Drei Cache-Ebenen als Ursache

0. Das eine Cache-Prinzip

Vor CocoaPods, DerivedData, PUB_CACHE gilt für alle Keys:

CI-Cache bindet Build-Determinismus — nicht „Dateien lagern“.

• pubspec.lock / Podfile.lock ändern → Miss → erwartet
• Xcode/Flutter-SDK-Upgrade → Miss → erwartet
• Job-Zeit, Datum, Zufallssuffix allein → nicht

Symptom: täglicher Kaltstart — Caches per Datum oder Vollwipe statt Lockfile+Version.

0.1 Echte Engpass-Reihenfolge

Alle Abschnitte folgen einem Urteil — Ebenen sind ungleich:

Time ceiling (optimize in this order):
  CocoaPods (network + resolve)  🔥🔥🔥  often ~70% of ceiling
        ↓
  DerivedData (compile increment) 🔥🔥    hot builds → ~6 min tier
        ↓
  Flutter cache (toolchain)       🔥      mainly first-run pub / engine

Urteil: Langsamkeit ist selten drei parallele Probleme — Pods deckeln zuerst; bei Pods-Miss hilft DerivedData nur downstream ins Leere.

Lesepfad: 10 Min → §0+§0.1+§4; Cold ~15 Min, Hot langsam → §5; §6 für Image und erstes pub.

1. Einzelursache: Propagation bis IPA

Keine drei Subsysteme — eine Kette. Bruch upstream oder downstream?

Hängt flutter build ipa bei Running pod install..., §0.1: Pods-Cache/Netz vor Xcode-Flags. Messen: pub → pod → xcodebuild.

1.1 Kette

In Kausalrichtung lesen:

  [start · primary]  CocoaPods miss / slow private specs
           │  Pod tree rebuild, Specs fetch
           ▼
  [propagate]        DerivedData forced cold (full xcodebuild)
           │
           ▼
  [end]              Slow IPA (often blamed on Flutter/Dart)

Rückwärts: pubspec.lock → Plugins → pod → DerivedData weg. Restore: Pub zuerst; Debug-Budget: Pods → DerivedData → Flutter.

Zitat: ~90 % „Flutter CI langsam“ = Upstream-Kette, nicht Compiler.

Offiziell: Flutter iOS deployment · CocoaPods environment · Xcode Build Settings.

2. Benchmark: §0.1-Gewichte

Tabelle belegt Pods zuerst, DerivedData danach. kvmboot-Typisch (mittleres Flutter, ~40 Pods, Release, Cloud Mac M4); gleicher Commit.

Cold >20 Min → §4, nicht §5. Cold ~11, Hot >12 → §5 restore.

Selbsttest: Vier Zeilen wall time; Commit und FLUTTER_VERSION fixieren.

3. Dual-Agent auf einem Host: Grenzen

Begleitartikel vom 2026-06-03: Cloud Mac Dual-AI-Agent: Claude Code + Codex-Isolation (2026-06-03) — zwei CLIs, ein Worktree intakt. Mit Nacht-Flutter-CI auf demselben gemieteten Mac:

• Getrennte Cache-Wurzeln: CI-DERIVED_DATA_PATH, nicht Agent-DerivedData.
• Getrennte Planung: paralleles xcodebuild + Indexierung → Swap; 16 GB: Agent tags, CI nachts.
• Kein Kreuz: kein pod update auf CI-ios/Pods.

4. CocoaPods CI 🔥🔥🔥

Primärschicht. ~70 % Flutter iOS build slow in pod install. 28→19 Min hier — sonst rettet DerivedData nicht. §0: Podfile.lock.

4.1 Umgebung

export CP_HOME_DIR="${CP_HOME_DIR:-$HOME/.cocoapods}"
export COCOAPODS_PARALLEL_CODE_DOWNLOAD=true
# persist: ~/.cocoapods/repos + ~/Library/Caches/CocoaPods

Private Specs: GitHub Actions macOS runner / Self-hosted Cloud Mac in Git-Region. Bitrise vs Self-hosted Mac Runner.

4.2 Pods/-Baum

• Üblich: ios/Pods cachen.
• Compliance: Pods/ committen, --deployment.

Kein blindes pod update.

Explizit pod install --verbose vor flutter build ipa.

5. DerivedData 🔥🔥

Nach Pods-Treffer Hot ~6 Min.

export DERIVED_DATA_PATH="/var/ci/derived/flutter-${FLUTTER_VERSION}-xcode-${XCODE_VERSION}"
xcodebuild -workspace ios/Runner.xcworkspace -scheme Runner \
  -configuration Release -derivedDataPath "$DERIVED_DATA_PATH" \
  -destination 'generic/platform=iOS' build

Tier-Sweep; Disk: Runner-Disk- und Inode-Governance.

6. Flutter-Toolchain 🔥

Erstlauf-Downloads.

Nicht build/ios cross-job; Docker-Aufteilung.

7. GitHub Actions Pipeline

§4–§6 als YAML.

# .github/workflows/flutter-ios.yml (structure; macos-latest or self-hosted cloud Mac)
jobs:
  build-ios:
    runs-on: macos-14   # or runs-on: [self-hosted, cloud-mac]
    steps:
      - uses: actions/checkout@v4

      # ── Restore (order: Pub → Pods Specs → Pods tree → DerivedData) ──
      - name: Restore Pub Cache
        uses: actions/cache/restore@v4
        with:
          path: ${{ env.PUB_CACHE }}
          key: pub-${{ hashFiles('pubspec.lock') }}-flutter-${{ env.FLUTTER_VERSION }}

      - name: Restore CocoaPods Specs
        uses: actions/cache/restore@v4
        with:
          path: |
            ~/.cocoapods
            ~/Library/Caches/CocoaPods
          key: pods-specs-${{ env.COCOAPODS_VERSION }}

      - name: Restore Pods Tree
        uses: actions/cache/restore@v4
        with:
          path: ios/Pods
          key: pods-tree-${{ hashFiles('ios/Podfile.lock') }}

      - name: Restore DerivedData
        uses: actions/cache/restore@v4
        with:
          path: ${{ env.DERIVED_DATA_PATH }}
          key: dd-${{ env.XCODE_VERSION }}-${{ env.FLUTTER_VERSION }}-${{ hashFiles('pubspec.lock', 'ios/Podfile.lock') }}

      # ── Build ──
      - name: Flutter Pub Get
        run: flutter pub get

      - name: Pod Install
        run: cd ios && pod install --verbose

      - name: Flutter Build IPA
        run: flutter build ipa --release --export-options-plist=ios/ExportOptions.plist

      # ── Save (mirror restore; save costly layers even on failure) ──
      - name: Save Pub Cache
        uses: actions/cache/save@v4
        if: always()
        with:
          path: ${{ env.PUB_CACHE }}
          key: pub-${{ hashFiles('pubspec.lock') }}-flutter-${{ env.FLUTTER_VERSION }}

      - name: Save Pods + DerivedData
        uses: actions/cache/save@v4
        if: always()
        with:
          path: |
            ~/.cocoapods
            ~/Library/Caches/CocoaPods
            ios/Pods
            ${{ env.DERIVED_DATA_PATH }}
          key: dd-${{ env.XCODE_VERSION }}-${{ env.FLUTTER_VERSION }}-${{ hashFiles('pubspec.lock', 'ios/Podfile.lock') }}

Signierung: codesign / Notarization.

Fallen: pod vor restore; kein save bei Fail — if: always().

8. Disk/Inode

Drei Ebenen → 60 % auf 256 GB; inode oft zuerst. Release-Sprint-Matrix.

du -sh ~/Library/Developer/Xcode/DerivedData ~/.cocoapods "${PUB_CACHE:-$HOME/.pub-cache}" 2>/dev/null
df -h .; df -i .

9. Abnahme

① pod <90s ② Hot −40 % ③ pub optional.

10. FAQ

10.1 Warum so langsam auf Cloud Mac?

CocoaPods-Miss → Kette. Pods zuerst.

10.2 Pods oder DerivedData?

Pods zuerst.

10.3 Nur DerivedData?

Nein.

10.4 Runner-Cache?

§7; if: always().

10.5 Dual-Agent?

2026-06-03: worktree; hier CI-Cache.

11. Fazit

CocoaPods (🔥🔥🔥) → DerivedData (🔥🔥) → Flutter (🔥).