.github: speed up cigocacher build with a small bootstrap cachetomhjp/cigocacher-cache

This reduces the time to build cigocacher from 25-30s to ~5s including
the cache restore step, as the cache is only ~20MB.

I also discovered while adding this step that the **/go.sum pattern was
taking 5-15s to evaluate because it's traversing the whole checkout tree
structure, but we only have one go.sum file in the repo that we want to
do content cache busting for. Replacing ** with * means we only look one
level deep for go.sum (in the src/ checkout dir), and knocks 5-15s off
every job.

Updates #10808

Change-Id: I6ccb0c53593e0ccb4048734bb3a0624e23bd17f2
Signed-off-by: Tom Proctor <tomhjp@users.noreply.github.com>

1 files changed, 40 insertions, 16 deletions

diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index fd193401d..f1a5cdbb2 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -144,10 +144,10 @@ jobs:
         path: |
           ~/.cache/go-build
           ~\AppData\Local\go-build
-        key: ${{ runner.os }}-${{ matrix.goarch }}-${{ matrix.buildflags }}-go-${{ matrix.shard }}-${{ hashFiles('**/go.sum') }}-${{ github.job }}-${{ github.run_id }}
+        key: ${{ runner.os }}-${{ matrix.goarch }}-${{ matrix.buildflags }}-go-${{ matrix.shard }}-${{ hashFiles('*/go.sum') }}-${{ github.job }}-${{ github.run_id }}
         restore-keys: |
-          ${{ runner.os }}-${{ matrix.goarch }}-${{ matrix.buildflags }}-go-${{ matrix.shard }}-${{ hashFiles('**/go.sum') }}-${{ github.job }}-
-          ${{ runner.os }}-${{ matrix.goarch }}-${{ matrix.buildflags }}-go-${{ matrix.shard }}-${{ hashFiles('**/go.sum') }}-
+          ${{ runner.os }}-${{ matrix.goarch }}-${{ matrix.buildflags }}-go-${{ matrix.shard }}-${{ hashFiles('*/go.sum') }}-${{ github.job }}-
+          ${{ runner.os }}-${{ matrix.goarch }}-${{ matrix.buildflags }}-go-${{ matrix.shard }}-${{ hashFiles('*/go.sum') }}-
           ${{ runner.os }}-${{ matrix.goarch }}-${{ matrix.buildflags }}-go-${{ matrix.shard }}-
           ${{ runner.os }}-${{ matrix.goarch }}-${{ matrix.buildflags }}-go-
     - name: build all
@@ -215,7 +215,7 @@ jobs:
         path: |
           ~/.cache/go-build
           ~\AppData\Local\go-build
-        key: ${{ runner.os }}-${{ matrix.goarch }}-${{ matrix.buildflags }}-go-${{ matrix.shard }}-${{ hashFiles('**/go.sum') }}-${{ github.job }}-${{ github.run_id }}
+        key: ${{ runner.os }}-${{ matrix.goarch }}-${{ matrix.buildflags }}-go-${{ matrix.shard }}-${{ hashFiles('*/go.sum') }}-${{ github.job }}-${{ github.run_id }}
 
   windows:
     permissions:
@@ -256,6 +256,20 @@ jobs:
         key: ${{ needs.gomod-cache.outputs.cache-key }}
         enableCrossOsArchive: true
 
+    - name: Restore bootstrap cache
+      id: restore-cache
+      uses: actions/cache/restore@0400d5f644dc74513175e3cd8d07132dd4860809 # v4.2.4
+      with:
+        # Note: this is only restoring the build cache. Mod cache is shared amongst
+        # all jobs in the workflow.
+        path: |
+          ~/.cache/go-build
+          ~\AppData\Local\go-build
+        key: cigocacher-${{ runner.os }}-${{ runner.arch }}-${{ hashFiles('*/go.sum', '*/cmd/cigocacher/**') }}
+        restore-keys: |
+          cigocacher-${{ runner.os }}-${{ runner.arch }}-${{ hashFiles('*/go.sum', '*/cmd/cigocacher/**') }}
+          cigocacher-${{ runner.os }}-${{ runner.arch }}-
+
     - name: Set up cigocacher
       id: cigocacher-setup
       uses: ./src/.github/actions/go-cache
@@ -264,6 +278,16 @@ jobs:
         cache-dir: ${{ github.workspace }}/cigocacher
         cigocached-url: ${{ vars.CIGOCACHED_AZURE_URL }}
 
+    - name: Save bootstrap cache
+      # Only save on cache miss and main branch to avoid thrashing.
+      if: steps.restore-cache.outputs.cache-hit != 'true' && github.ref == 'refs/heads/main'
+      uses: actions/cache/save@0400d5f644dc74513175e3cd8d07132dd4860809 # v4.2.4
+      with:
+        path: |
+          ~/.cache/go-build
+          ~\AppData\Local\go-build
+        key: cigocacher-${{ runner.os }}-${{ runner.arch }}-${{ hashFiles('*/go.sum', '*/cmd/cigocacher/**') }}
+
     - name: test
       if: matrix.key != 'win-bench' # skip on bench builder
       working-directory: src
@@ -401,10 +425,10 @@ jobs:
         path: |
           ~/.cache/go-build
           ~\AppData\Local\go-build
-        key: ${{ runner.os }}-${{ matrix.goos }}-${{ matrix.goarch }}-${{ matrix.goarm }}-go-${{ hashFiles('**/go.sum') }}-${{ github.job }}-${{ github.run_id }}
+        key: ${{ runner.os }}-${{ matrix.goos }}-${{ matrix.goarch }}-${{ matrix.goarm }}-go-${{ hashFiles('*/go.sum') }}-${{ github.job }}-${{ github.run_id }}
         restore-keys: |
-          ${{ runner.os }}-${{ matrix.goos }}-${{ matrix.goarch }}-${{ matrix.goarm }}-go-${{ hashFiles('**/go.sum') }}-${{ github.job }}-
-          ${{ runner.os }}-${{ matrix.goos }}-${{ matrix.goarch }}-${{ matrix.goarm }}-go-${{ hashFiles('**/go.sum') }}-
+          ${{ runner.os }}-${{ matrix.goos }}-${{ matrix.goarch }}-${{ matrix.goarm }}-go-${{ hashFiles('*/go.sum') }}-${{ github.job }}-
+          ${{ runner.os }}-${{ matrix.goos }}-${{ matrix.goarch }}-${{ matrix.goarm }}-go-${{ hashFiles('*/go.sum') }}-
           ${{ runner.os }}-${{ matrix.goos }}-${{ matrix.goarch }}-${{ matrix.goarm }}-go-
     - name: build all
       working-directory: src
@@ -436,7 +460,7 @@ jobs:
         path: |
           ~/.cache/go-build
           ~\AppData\Local\go-build
-        key: ${{ runner.os }}-${{ matrix.goos }}-${{ matrix.goarch }}-${{ matrix.goarm }}-go-${{ hashFiles('**/go.sum') }}-${{ github.job }}-${{ github.run_id }}
+        key: ${{ runner.os }}-${{ matrix.goos }}-${{ matrix.goarch }}-${{ matrix.goarm }}-go-${{ hashFiles('*/go.sum') }}-${{ github.job }}-${{ github.run_id }}
 
   ios: # similar to cross above, but iOS can't build most of the repo. So, just
        # make it build a few smoke packages.
@@ -500,10 +524,10 @@ jobs:
         path: |
           ~/.cache/go-build
           ~\AppData\Local\go-build
-        key: ${{ runner.os }}-${{ matrix.goos }}-${{ matrix.goarch }}-go-${{ hashFiles('**/go.sum') }}-${{ github.job }}-${{ github.run_id }}
+        key: ${{ runner.os }}-${{ matrix.goos }}-${{ matrix.goarch }}-go-${{ hashFiles('*/go.sum') }}-${{ github.job }}-${{ github.run_id }}
         restore-keys: |
-          ${{ runner.os }}-${{ matrix.goos }}-${{ matrix.goarch }}-go-${{ hashFiles('**/go.sum') }}-${{ github.job }}-
-          ${{ runner.os }}-${{ matrix.goos }}-${{ matrix.goarch }}-go-${{ hashFiles('**/go.sum') }}-
+          ${{ runner.os }}-${{ matrix.goos }}-${{ matrix.goarch }}-go-${{ hashFiles('*/go.sum') }}-${{ github.job }}-
+          ${{ runner.os }}-${{ matrix.goos }}-${{ matrix.goarch }}-go-${{ hashFiles('*/go.sum') }}-
           ${{ runner.os }}-${{ matrix.goos }}-${{ matrix.goarch }}-go-
     - name: build core
       working-directory: src
@@ -528,7 +552,7 @@ jobs:
         path: |
           ~/.cache/go-build
           ~\AppData\Local\go-build
-        key: ${{ runner.os }}-${{ matrix.goos }}-${{ matrix.goarch }}-go-${{ hashFiles('**/go.sum') }}-${{ github.job }}-${{ github.run_id }}
+        key: ${{ runner.os }}-${{ matrix.goos }}-${{ matrix.goarch }}-go-${{ hashFiles('*/go.sum') }}-${{ github.job }}-${{ github.run_id }}
 
   android:
     # similar to cross above, but android fails to build a few pieces of the
@@ -581,10 +605,10 @@ jobs:
         path: |
           ~/.cache/go-build
           ~\AppData\Local\go-build
-        key: ${{ runner.os }}-js-wasm-go-${{ hashFiles('**/go.sum') }}-${{ github.job }}-${{ github.run_id }}
+        key: ${{ runner.os }}-js-wasm-go-${{ hashFiles('*/go.sum') }}-${{ github.job }}-${{ github.run_id }}
         restore-keys: |
-          ${{ runner.os }}-js-wasm-go-${{ hashFiles('**/go.sum') }}-${{ github.job }}-
-          ${{ runner.os }}-js-wasm-go-${{ hashFiles('**/go.sum') }}-
+          ${{ runner.os }}-js-wasm-go-${{ hashFiles('*/go.sum') }}-${{ github.job }}-
+          ${{ runner.os }}-js-wasm-go-${{ hashFiles('*/go.sum') }}-
           ${{ runner.os }}-js-wasm-go-
     - name: build tsconnect client
       working-directory: src
@@ -614,7 +638,7 @@ jobs:
         path: |
           ~/.cache/go-build
           ~\AppData\Local\go-build
-        key: ${{ runner.os }}-js-wasm-go-${{ hashFiles('**/go.sum') }}-${{ github.job }}-${{ github.run_id }}
+        key: ${{ runner.os }}-js-wasm-go-${{ hashFiles('*/go.sum') }}-${{ github.job }}-${{ github.run_id }}
 
   tailscale_go: # Subset of tests that depend on our custom Go toolchain.
     runs-on: ubuntu-24.04