From 8032b966a16b5b843a0e8cca2a7b1e6f1eb2bf12 Mon Sep 17 00:00:00 2001
From: James Tucker <james@tailscale.com>
Date: Wed, 26 Apr 2023 11:02:18 -0700
Subject: [PATCH] .github/workflows: add recency bias to action cache keys

The action cache restore process either matches the restore key pattern
exactly, or uses a matching prefix with the most recent date.

If the restore key is an exact match, then no updates are uploaded, but
if we've just computed tests executions for more recent code then we
will likely want to use those results in future runs.

Appending run_id to the cache key will give us an always new key, and
then we will be restore a recently uploaded cache that is more likely
has a higher overlap with the code being tested.

Updates #7975

Signed-off-by: James Tucker <james@tailscale.com>
---
 .github/workflows/test.yml | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 8e2d9b5b1..1116f428d 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -65,8 +65,9 @@ jobs:
           ~\AppData\Local\go-build
         # The -2- here should be incremented when the scheme of data to be
         # cached changes (e.g. path above changes).
-        key: ${{ github.job }}-${{ runner.os }}-${{ matrix.goarch }}-${{ matrix.buildflags }}-go-2-${{ hashFiles('**/go.sum') }}
+        key: ${{ github.job }}-${{ runner.os }}-${{ matrix.goarch }}-${{ matrix.buildflags }}-go-2-${{ hashFiles('**/go.sum') }}-${{ github.run_id }}
         restore-keys: |
+          ${{ github.job }}-${{ runner.os }}-${{ matrix.goarch }}-${{ matrix.buildflags }}-go-2-${{ hashFiles('**/go.sum') }}
           ${{ github.job }}-${{ runner.os }}-${{ matrix.goarch }}-${{ matrix.buildflags }}-go-2-
     - name: build all
       run: ./tool/go build ${{matrix.buildflags}} ./...
@@ -135,8 +136,9 @@ jobs:
           ~\AppData\Local\go-build
         # The -2- here should be incremented when the scheme of data to be
         # cached changes (e.g. path above changes).
-        key: ${{ github.job }}-${{ runner.os }}-go-2-${{ hashFiles('**/go.sum') }}
+        key: ${{ github.job }}-${{ runner.os }}-go-2-${{ hashFiles('**/go.sum') }}-${{ github.run_id }}
         restore-keys: |
+          ${{ github.job }}-${{ runner.os }}-go-2-${{ hashFiles('**/go.sum') }}
           ${{ github.job }}-${{ runner.os }}-go-2-
     - name: test
       # Don't use -bench=. -benchtime=1x.
@@ -210,8 +212,9 @@ jobs:
           ~\AppData\Local\go-build
         # The -2- here should be incremented when the scheme of data to be
         # cached changes (e.g. path above changes).
-        key: ${{ github.job }}-${{ runner.os }}-${{ matrix.goos }}-${{ matrix.goarch }}-go-2-${{ hashFiles('**/go.sum') }}
+        key: ${{ github.job }}-${{ runner.os }}-${{ matrix.goos }}-${{ matrix.goarch }}-go-2-${{ hashFiles('**/go.sum') }}-${{ github.run_id }}
         restore-keys: |
+          ${{ github.job }}-${{ runner.os }}-${{ matrix.goos }}-${{ matrix.goarch }}-go-2-${{ hashFiles('**/go.sum') }}
           ${{ github.job }}-${{ runner.os }}-${{ matrix.goos }}-${{ matrix.goarch }}-go-2-
     - name: build all
       run: ./tool/go build ./cmd/...
@@ -275,8 +278,9 @@ jobs:
           ~\AppData\Local\go-build
         # The -2- here should be incremented when the scheme of data to be
         # cached changes (e.g. path above changes).
-        key: ${{ github.job }}-${{ runner.os }}-go-2-${{ hashFiles('**/go.sum') }}
+        key: ${{ github.job }}-${{ runner.os }}-go-2-${{ hashFiles('**/go.sum') }}-${{ github.run_id }}
         restore-keys: |
+          ${{ github.job }}-${{ runner.os }}-go-2-${{ hashFiles('**/go.sum') }}
           ${{ github.job }}-${{ runner.os }}-go-2-
     - name: build tsconnect client
       run: ./tool/go build ./cmd/tsconnect/wasm ./cmd/tailscale/cli