ci: cache embedded postgres downloaded binaries (#18477)

Updates CI job definitions to cache downloaded binaries for embedded-postgres.

.github/actions/embedded-pg-cache/download/action.yml

@@ -0,0 +1,47 @@
+name: "Download Embedded Postgres Cache"
+description: |
+  Downloads the embedded postgres cache and outputs today's cache key.
+  A PR job can use a cache if it was created by its base branch, its current
+  branch, or the default branch.
+  https://docs.github.com/en/actions/writing-workflows/choosing-what-your-workflow-does/caching-dependencies-to-speed-up-workflows#restrictions-for-accessing-a-cache
+outputs:
+  cache-key:
+    description: "Today's cache key"
+    value: ${{ steps.vars.outputs.cache-key }}
+inputs:
+  key-prefix:
+    description: "Prefix for the cache key"
+    required: true
+  cache-path:
+    description: "Path to the cache directory"
+    required: true
+runs:
+  using: "composite"
+  steps:
+    - name: Get date values and cache key
+      id: vars
+      shell: bash
+      run: |
+        export YEAR_MONTH=$(date +'%Y-%m')
+        export PREV_YEAR_MONTH=$(date -d 'last month' +'%Y-%m')
+        export DAY=$(date +'%d')
+        echo "year-month=$YEAR_MONTH" >> $GITHUB_OUTPUT
+        echo "prev-year-month=$PREV_YEAR_MONTH" >> $GITHUB_OUTPUT
+        echo "cache-key=${{ inputs.key-prefix }}-${YEAR_MONTH}-${DAY}" >> $GITHUB_OUTPUT
+
+    # By default, depot keeps caches for 14 days. This is plenty for embedded
+    # postgres, which changes infrequently.
+    # https://depot.dev/docs/github-actions/overview#cache-retention-policy
+    - name: Download embedded Postgres cache
+      uses: actions/cache/restore@5a3ec84eff668545956fd18022155c47e93e2684 # v4.2.3
+      with:
+        path: ${{ inputs.cache-path }}
+        key: ${{ steps.vars.outputs.cache-key }}
+        # > If there are multiple partial matches for a restore key, the action returns the most recently created cache.
+        # https://docs.github.com/en/actions/writing-workflows/choosing-what-your-workflow-does/caching-dependencies-to-speed-up-workflows#matching-a-cache-key
+        # The second restore key allows non-main branches to use the cache from the previous month.
+        # This prevents PRs from rebuilding the cache on the first day of the month.
+        # It also makes sure that once a month, the cache is fully reset.
+        restore-keys: |
+          ${{ inputs.key-prefix }}-${{ steps.vars.outputs.year-month }}-
+          ${{ github.ref != 'refs/heads/main' && format('{0}-{1}-', inputs.key-prefix, steps.vars.outputs.prev-year-month) || '' }}

.github/actions/embedded-pg-cache/upload/action.yml

@@ -0,0 +1,18 @@
+name: "Upload Embedded Postgres Cache"
+description: Uploads the embedded Postgres cache. This only runs on the main branch.
+inputs:
+  cache-key:
+    description: "Cache key"
+    required: true
+  cache-path:
+    description: "Path to the cache directory"
+    required: true
+runs:
+  using: "composite"
+  steps:
+    - name: Upload Embedded Postgres cache
+      if: ${{ github.ref == 'refs/heads/main' }}
+      uses: actions/cache/save@5a3ec84eff668545956fd18022155c47e93e2684 # v4.2.3
+      with:
+        path: ${{ inputs.cache-path }}
+        key: ${{ inputs.cache-key }}

.github/actions/setup-embedded-pg-cache-paths/action.yml

@@ -0,0 +1,33 @@
+name: "Setup Embedded Postgres Cache Paths"
+description: Sets up a path for cached embedded postgres binaries.
+outputs:
+  embedded-pg-cache:
+    description: "Value of EMBEDDED_PG_CACHE_DIR"
+    value: ${{ steps.paths.outputs.embedded-pg-cache }}
+  cached-dirs:
+    description: "directories that should be cached between CI runs"
+    value: ${{ steps.paths.outputs.cached-dirs }}
+runs:
+  using: "composite"
+  steps:
+    - name: Override Go paths
+      id: paths
+      uses: actions/github-script@60a0d83039c74a4aee543508d2ffcb1c3799cdea # v7
+      with:
+        script: |
+          const path = require('path');
+
+          // RUNNER_TEMP should be backed by a RAM disk on Windows if
+          // coder/setup-ramdisk-action was used
+          const runnerTemp = process.env.RUNNER_TEMP;
+          const embeddedPgCacheDir = path.join(runnerTemp, 'embedded-pg-cache');
+          core.exportVariable('EMBEDDED_PG_CACHE_DIR', embeddedPgCacheDir);
+          core.setOutput('embedded-pg-cache', embeddedPgCacheDir);
+          const cachedDirs = `${embeddedPgCacheDir}`;
+          core.setOutput('cached-dirs', cachedDirs);
+
+    - name: Create directories
+      shell: bash
+      run: |
+        set -e
+        mkdir -p "$EMBEDDED_PG_CACHE_DIR"

.github/workflows/ci.yaml

@@ -473,6 +473,17 @@ jobs:
         with:
           key-prefix: test-go-pg-${{ runner.os }}-${{ runner.arch }}
 
+      - name: Setup Embedded Postgres Cache Paths
+        id: embedded-pg-cache
+        uses: ./.github/actions/setup-embedded-pg-cache-paths
+
+      - name: Download Embedded Postgres Cache
+        id: download-embedded-pg-cache
+        uses: ./.github/actions/embedded-pg-cache/download
+        with:
+          key-prefix: embedded-pg-${{ runner.os }}-${{ runner.arch }}
+          cache-path: ${{ steps.embedded-pg-cache.outputs.cached-dirs }}
+
       - name: Normalize File and Directory Timestamps
         shell: bash
         # Normalize file modification timestamps so that go test can use the
@@ -497,12 +508,12 @@ jobs:
             # Create a temp dir on the R: ramdisk drive for Windows. The default
             # C: drive is extremely slow: https://github.com/actions/runner-images/issues/8755
             mkdir -p "R:/temp/embedded-pg"
-            go run scripts/embedded-pg/main.go -path "R:/temp/embedded-pg"
+            go run scripts/embedded-pg/main.go -path "R:/temp/embedded-pg" -cache "${EMBEDDED_PG_CACHE_DIR}"
           elif [ "${{ runner.os }}" == "macOS" ]; then
             # Postgres runs faster on a ramdisk on macOS too
             mkdir -p /tmp/tmpfs
             sudo mount_tmpfs -o noowners -s 8g /tmp/tmpfs
-            go run scripts/embedded-pg/main.go -path /tmp/tmpfs/embedded-pg
+            go run scripts/embedded-pg/main.go -path /tmp/tmpfs/embedded-pg -cache "${EMBEDDED_PG_CACHE_DIR}"
           elif [ "${{ runner.os }}" == "Linux" ]; then
             make test-postgres-docker
           fi
@@ -571,6 +582,14 @@ jobs:
         with:
           cache-key: ${{ steps.download-cache.outputs.cache-key }}
 
+      - name: Upload Embedded Postgres Cache
+        uses: ./.github/actions/embedded-pg-cache/upload
+        # We only use the embedded Postgres cache on macOS and Windows runners.
+        if: runner.OS == 'macOS' || runner.OS == 'Windows'
+        with:
+          cache-key: ${{ steps.download-embedded-pg-cache.outputs.cache-key }}
+          cache-path: "${{ steps.embedded-pg-cache.outputs.embedded-pg-cache }}"
+
       - name: Upload test stats to Datadog
         timeout-minutes: 1
         continue-on-error: true