Optimize CI caches (#37387)

Cache includes go, lint and unittests. Integration tests with their
standalone binaries are uncacheable with their current architecture.

Every Go job uses a new composite action (`.github/actions/go-cache`)
that restores and saves the Go module cache, a shared build cache, and
the golangci-lint cache. A `cache-seeder` workflow runs on `push: main`
to pre-populate those slots; PRs read them via GitHub's default-branch
fallback, so the common case is warm from the first commit.

Also dropped `-coverprofile` from `test-unit` (it silently disabled Go's
test result cache), and `-race` from `test-pgsql` and `test-mysql` (kept
on `test-unit` and `test-sqlite`).

Signed-off-by: silverwind <me@silverwind.io>
Co-authored-by: Claude (Opus 4.7) <noreply@anthropic.com>
Co-authored-by: Nicolas <bircni@icloud.com>

.github/actions/go-cache/action.yml

@@ -0,0 +1,47 @@
+name: go-caches
+description: Restore and save go module, build, and golangci-lint caches
+
+inputs:
+  cache-name:
+    description: Short identifier used in the per-caller build cache key
+    required: true
+  build-cache:
+    description: Whether to include ~/.cache/go-build
+    default: "true"
+  build-cache-rotate:
+    description: Whether to rotate the build cache key per run so Go's test result cache can accumulate across runs
+    default: "false"
+  lint-cache:
+    description: Whether to include ~/.cache/golangci-lint
+    default: "false"
+
+runs:
+  using: composite
+  steps:
+    - uses: actions/cache@27d5ce7f107fe9357f9df03efb73ab90386fccae # v5.0.5
+      with:
+        path: ~/go/pkg/mod
+        key: gomod-${{ runner.os }}-${{ runner.arch }}-${{ hashFiles('go.sum') }}
+        restore-keys: gomod-${{ runner.os }}-${{ runner.arch }}
+    - if: ${{ inputs.build-cache == 'true' && inputs.build-cache-rotate == 'true' }}
+      uses: actions/cache@27d5ce7f107fe9357f9df03efb73ab90386fccae # v5.0.5
+      with:
+        path: ~/.cache/go-build
+        key: gobuild-${{ runner.os }}-${{ runner.arch }}-${{ inputs.cache-name }}-${{ hashFiles('go.sum') }}-${{ github.run_id }}
+        restore-keys: |
+          gobuild-${{ runner.os }}-${{ runner.arch }}-${{ inputs.cache-name }}-${{ hashFiles('go.sum') }}
+          gobuild-${{ runner.os }}-${{ runner.arch }}-${{ inputs.cache-name }}
+          gobuild-${{ runner.os }}-${{ runner.arch }}-${{ hashFiles('go.sum') }}
+          gobuild-${{ runner.os }}-${{ runner.arch }}
+    - if: ${{ inputs.build-cache == 'true' && inputs.build-cache-rotate != 'true' }}
+      uses: actions/cache@27d5ce7f107fe9357f9df03efb73ab90386fccae # v5.0.5
+      with:
+        path: ~/.cache/go-build
+        key: gobuild-${{ runner.os }}-${{ runner.arch }}-${{ hashFiles('go.sum') }}
+        restore-keys: gobuild-${{ runner.os }}-${{ runner.arch }}
+    - if: ${{ inputs.lint-cache == 'true' }}
+      uses: actions/cache@27d5ce7f107fe9357f9df03efb73ab90386fccae # v5.0.5
+      with:
+        path: ~/.cache/golangci-lint
+        key: golangci-${{ runner.os }}-${{ runner.arch }}-${{ inputs.cache-name }}-${{ hashFiles('go.sum', '.golangci.yml') }}
+        restore-keys: golangci-${{ runner.os }}-${{ runner.arch }}-${{ inputs.cache-name }}

.github/workflows/cache-seeder.yml

@@ -0,0 +1,75 @@
+# Populates the go module, build, and golangci-lint caches under the default
+# branch's cache scope so that PR runs have a warm fallback to restore from.
+#
+# GitHub Actions caches are scoped per ref: a PR run can only write to its own
+# branch's scope, but can read from the base branch's scope as a fallback.
+# PRs therefore cannot seed main's scope themselves. Running the same cache
+# steps on push-to-main is the only opportunity to populate that fallback
+# scope so fresh PR branches start with a useful cache on first run.
+
+# A PR job's exact key lives in its own PR-scope (empty on first run, filled
+# by later runs of the same PR); on miss, actions/cache's restore-keys fall
+# back to prefix matches against entries this seeder saves in main's scope.
+
+name: cache-seeder
+
+on:
+  push:
+    branches:
+      - main
+    paths:
+      - "go.sum"
+      - ".golangci.yml"
+      - ".github/actions/go-cache/action.yml"
+      - ".github/workflows/cache-seeder.yml"
+
+concurrency:
+  group: cache-seeder
+  cancel-in-progress: true
+
+jobs:
+  gobuild:
+    runs-on: ubuntu-latest
+    permissions:
+      contents: read
+    steps:
+      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
+      - uses: actions/setup-go@4a3601121dd01d1626a1e23e37211e3254c1c06c # v6.4.0
+        with:
+          go-version-file: go.mod
+          check-latest: true
+          cache: false
+      - uses: ./.github/actions/go-cache
+        with:
+          cache-name: seed
+      - run: make deps-backend
+      - run: TAGS="bindata" make backend
+      - run: TAGS="bindata sqlite sqlite_unlock_notify" make backend
+      - run: TAGS="bindata gogit sqlite sqlite_unlock_notify" GOEXPERIMENT="" make backend
+
+  lint:
+    runs-on: ubuntu-latest
+    permissions:
+      contents: read
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - { job: lint-backend, tags: "bindata sqlite sqlite_unlock_notify", target: "lint-backend" }
+          - { job: lint-go-windows, tags: "bindata sqlite sqlite_unlock_notify", target: "lint-go-windows" }
+          - { job: lint-go-gogit, tags: "bindata sqlite sqlite_unlock_notify gogit", target: "lint-go" }
+    steps:
+      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
+      - uses: actions/setup-go@4a3601121dd01d1626a1e23e37211e3254c1c06c # v6.4.0
+        with:
+          go-version-file: go.mod
+          check-latest: true
+          cache: false
+      - uses: ./.github/actions/go-cache
+        with:
+          cache-name: ${{ matrix.job }}
+          lint-cache: "true"
+      - run: make deps-backend deps-tools
+      - run: make ${{ matrix.target }}
+        env:
+          TAGS: ${{ matrix.tags }}

.github/workflows/pull-compliance.yml

@@ -25,6 +25,11 @@ jobs:
         with:
           go-version-file: go.mod
           check-latest: true
+          cache: false
+      - uses: ./.github/actions/go-cache
+        with:
+          cache-name: lint-backend
+          lint-cache: "true"
       - run: make deps-backend deps-tools
       - run: make lint-backend
         env:
@@ -123,6 +128,11 @@ jobs:
         with:
           go-version-file: go.mod
           check-latest: true
+          cache: false
+      - uses: ./.github/actions/go-cache
+        with:
+          cache-name: lint-go-windows
+          lint-cache: "true"
       - run: make deps-backend deps-tools
       - run: make lint-go-windows
         env:
@@ -142,6 +152,11 @@ jobs:
         with:
           go-version-file: go.mod
           check-latest: true
+          cache: false
+      - uses: ./.github/actions/go-cache
+        with:
+          cache-name: lint-go-gogit
+          lint-cache: "true"
       - run: make deps-backend deps-tools
       - run: make lint-go
         env:
@@ -159,6 +174,11 @@ jobs:
         with:
           go-version-file: go.mod
           check-latest: true
+          cache: false
+      - uses: ./.github/actions/go-cache
+        with:
+          cache-name: checks-backend
+          build-cache: "false"
       - run: make deps-backend deps-tools
       - run: make --always-make checks-backend # ensure the "go-licenses" make target runs
 
@@ -194,6 +214,10 @@ jobs:
         with:
           go-version-file: go.mod
           check-latest: true
+          cache: false
+      - uses: ./.github/actions/go-cache
+        with:
+          cache-name: backend
       # no frontend build here as backend should be able to build
       # even without any frontend files
       - run: make deps-backend

.github/workflows/pull-db-tests.yml

@@ -47,6 +47,10 @@ jobs:
         with:
           go-version-file: go.mod
           check-latest: true
+          cache: false
+      - uses: ./.github/actions/go-cache
+        with:
+          cache-name: pgsql
       - name: Add hosts to /etc/hosts
         run: '[ -e "/.dockerenv" ] || [ -e "/run/.containerenv" ] || echo "127.0.0.1 pgsql ldap minio" | sudo tee -a /etc/hosts'
       - run: make deps-backend
@@ -60,7 +64,6 @@ jobs:
         timeout-minutes: 50
         env:
           TAGS: bindata gogit
-          RACE_ENABLED: true
           TEST_TAGS: gogit
           TEST_LDAP: 1
 
@@ -76,6 +79,10 @@ jobs:
         with:
           go-version-file: go.mod
           check-latest: true
+          cache: false
+      - uses: ./.github/actions/go-cache
+        with:
+          cache-name: sqlite
       - run: make deps-backend
       - run: GOEXPERIMENT='' make backend
         env:
@@ -135,6 +142,11 @@ jobs:
         with:
           go-version-file: go.mod
           check-latest: true
+          cache: false
+      - uses: ./.github/actions/go-cache
+        with:
+          cache-name: unit
+          build-cache-rotate: "true"
       - name: Add hosts to /etc/hosts
         run: '[ -e "/.dockerenv" ] || [ -e "/run/.containerenv" ] || echo "127.0.0.1 minio devstoreaccount1.azurite.local mysql elasticsearch meilisearch smtpimap" | sudo tee -a /etc/hosts'
       - run: make deps-backend
@@ -142,16 +154,18 @@ jobs:
         env:
           TAGS: bindata
       - name: unit-tests
-        run: make unit-test-coverage test-check
+        run: make test-backend test-check
         env:
           TAGS: bindata
           RACE_ENABLED: true
+          GOTESTFLAGS: -timeout=20m
           GITHUB_READ_TOKEN: ${{ secrets.GITHUB_READ_TOKEN }}
       - name: unit-tests-gogit
-        run: GOEXPERIMENT='' make unit-test-coverage test-check
+        run: GOEXPERIMENT='' make test-backend test-check
         env:
           TAGS: bindata gogit
           RACE_ENABLED: true
+          GOTESTFLAGS: -timeout=20m
           GITHUB_READ_TOKEN: ${{ secrets.GITHUB_READ_TOKEN }}
 
   test-mysql:
@@ -190,6 +204,10 @@ jobs:
         with:
           go-version-file: go.mod
           check-latest: true
+          cache: false
+      - uses: ./.github/actions/go-cache
+        with:
+          cache-name: mysql
       - name: Add hosts to /etc/hosts
         run: '[ -e "/.dockerenv" ] || [ -e "/run/.containerenv" ] || echo "127.0.0.1 mysql elasticsearch smtpimap" | sudo tee -a /etc/hosts'
       - run: make deps-backend
@@ -203,7 +221,6 @@ jobs:
         run: make test-mysql
         env:
           TAGS: bindata
-          RACE_ENABLED: true
           TEST_INDEXER_CODE_ES_URL: "http://elastic:changeme@elasticsearch:9200"
 
   test-mssql:
@@ -231,6 +248,10 @@ jobs:
         with:
           go-version-file: go.mod
           check-latest: true
+          cache: false
+      - uses: ./.github/actions/go-cache
+        with:
+          cache-name: mssql
       - name: Add hosts to /etc/hosts
         run: '[ -e "/.dockerenv" ] || [ -e "/run/.containerenv" ] || echo "127.0.0.1 mssql devstoreaccount1.azurite.local" | sudo tee -a /etc/hosts'
       - run: make deps-backend

.github/workflows/pull-e2e-tests.yml

@@ -25,6 +25,11 @@ jobs:
         with:
           go-version-file: go.mod
           check-latest: true
+          cache: false
+      - uses: ./.github/actions/go-cache
+        with:
+          cache-name: e2e
+          build-cache: "false"
       - uses: pnpm/action-setup@v5
       - uses: actions/setup-node@v6
         with: