From c4b0bd347b55cdc5a4f9077ca577d29e98e12e8f Mon Sep 17 00:00:00 2001
From: Wolfgang Walther <walther@technowledgy.de>
Date: Tue, 6 Feb 2024 21:56:54 +0100
Subject: [PATCH] ci: Only save caches on main and release branches

This restores caches on all branches and pull requests, but only stores
them on the main branch and release branches. This prevents those caches
from being evicted early when we hit the 10 GB limit quickly.
---
 .github/actions/cache-on-main/action.yaml | 31 +++++++++++++++++++++++
 .github/workflows/build.yaml              | 14 +++++-----
 2 files changed, 37 insertions(+), 8 deletions(-)
 create mode 100644 .github/actions/cache-on-main/action.yaml

diff --git a/.github/actions/cache-on-main/action.yaml b/.github/actions/cache-on-main/action.yaml
new file mode 100644
index 000000000..d0848bd88
--- /dev/null
+++ b/.github/actions/cache-on-main/action.yaml
@@ -0,0 +1,31 @@
+name: Cache on main
+
+description: Stores caches on main only, but restores them on all branches.
+
+inputs:
+  path:
+    description: Path(s) to cache
+    required: true
+  prefix:
+    description: Cache key prefix to be used in both primary key and restore-keys.
+    required: true
+  suffix:
+    description: Cache key suffix to be used only in primary key.
+
+runs:
+  using: composite
+  steps:
+    - uses: actions/cache@0c45773b623bea8c8e75f6c82b208c3cf94ea4f9 # v4.0.2
+      if: ${{ startsWith(github.ref, 'refs/heads/') }}
+      with:
+        path: ${{ inputs.path }}
+        key: ${{ runner.os }}-${{ inputs.prefix }}-${{ inputs.suffix }}
+        restore-keys: |
+          ${{ runner.os }}-${{ inputs.prefix }}-
+    - uses: actions/cache/restore@0c45773b623bea8c8e75f6c82b208c3cf94ea4f9 # v4.0.2
+      if: ${{ !startsWith(github.ref, 'refs/heads/') }}
+      with:
+        path: ${{ inputs.path }}
+        key: ${{ runner.os }}-${{ inputs.prefix }}-${{ inputs.suffix }}
+        restore-keys: |
+          ${{ runner.os }}-${{ inputs.prefix }}-
diff --git a/.github/workflows/build.yaml b/.github/workflows/build.yaml
index 1d8a494d2..43444a480 100644
--- a/.github/workflows/build.yaml
+++ b/.github/workflows/build.yaml
@@ -115,12 +115,11 @@ jobs:
     steps:
       - uses: actions/checkout@a5ac7e51b41094c92402da3b24376905380afc29 # v4.1.6
       - name: Stack working files cache
-        uses: actions/cache@0c45773b623bea8c8e75f6c82b208c3cf94ea4f9 # v4.0.2
+        uses: ./.github/actions/cache-on-main
         with:
           path: ${{ matrix.cache }}
-          key: stack-${{ runner.os }}-${{ hashFiles('stack.yaml.lock') }}
-          restore-keys: |
-            stack-${{ runner.os }}-
+          prefix: stack
+          suffix: ${{ hashFiles('stack.yaml.lock') }}
       - name: Install dependencies
         if: matrix.deps
         run: ${{ matrix.deps }}
@@ -171,15 +170,14 @@ jobs:
         run: |
           mkdir ~/.cabal
       - name: Cache
-        uses: actions/cache@0c45773b623bea8c8e75f6c82b208c3cf94ea4f9 # v4.0.2
+        uses: ./.github/actions/cache-on-main
         with:
           path: |
             ~/.cabal/packages
             ~/.cabal/store
             dist-newstyle
-          key: cabal-${{ runner.os }}-${{ matrix.ghc }}-${{ hashFiles('postgrest.cabal', 'cabal.project', 'cabal.project.freeze') }}
-          restore-keys: |
-            cabal-${{ runner.os }}-${{ matrix.ghc }}-
+          prefix: cabal-${{ matrix.ghc }}
+          suffix: ${{ hashFiles('postgrest.cabal', 'cabal.project', 'cabal.project.freeze') }}
       - name: Install dependencies
         run: |
           cabal update