Enable more persistent caches in CI

Author: vector-of-bool

.github/workflows/ci.yml

@@ -87,25 +87,29 @@ jobs:
           - { env: almalinux:8 --gts_version=12, vcpkg_arg: use_vcpkg=true }
     steps:
       - *checkout
+      - name: Prepare Caches
+        uses: actions/cache@v4
+        with:
+          path: _build/.cache
+          key: linux-${{matrix.env}}
       - name: Environment Prep
         run: |
-          bash tools/earthly.sh +init \
-            --env=${{matrix.env}} \
-            --${{matrix.vcpkg_arg}}
+          # Set Earthly args in the .arg file, which will persist across subsequent
+          # steps, ensuring each step uses the same argument set
+          echo "env=${{matrix.env}}"      >  .arg
+          echo "${{matrix.vcpkg_arg}}"    >> .arg
+          # Persist caches into a host directory to be persisted between runs
+          echo "host_cache=_build/.cache" >> .arg
+          # Enable unity builds in CI for faster compilation
+          echo "unity_build=true"         >> .arg
+
+          bash tools/earthly.sh +init
       - name: Build
-        run: |
-          bash tools/earthly.sh +build \
-            --env=${{matrix.env}} \
-            --${{matrix.vcpkg_arg}} \
-            --unity_build=true
+        run: bash tools/earthly.sh +build
       # This step will use the same cached +build results as long as all Earthly
-      # build arguments are equivalent. Make sure of that!
+      # build arguments are equivalent.
       - name: Test
-        run: |
-          bash tools/earthly.sh -a +test/results.xml results.xml \
-            --env=${{matrix.env}} \
-            --${{matrix.vcpkg_arg}} \
-            --unity_build=true
+        run: bash tools/earthly.sh -a +test/results.xml results.xml
 
   build-macos:
     name: Build & Test (macOS)
@@ -121,7 +125,7 @@ jobs:
       - name: Prepare Caches
         uses: actions/cache@v4
         with:
-          path: _build/_cache
+          path: _build/.cache
           key: macos-15
       - name: Prepare uv Environment
         run: uv run --group=build true
@@ -151,15 +155,15 @@ jobs:
           export CMAKE_OSX_ARCHITECTURES="${{matrix.target_arch}}"
 
           # Create a directory for vcpkg binary caches
-          export VCPKG_DEFAULT_BINARY_CACHE=$PWD/_build/_cache
+          export VCPKG_DEFAULT_BINARY_CACHE=$PWD/_build/.cache/vcpkg
           mkdir -p "$VCPKG_DEFAULT_BINARY_CACHE"
 
           # Do the build
           uv run --group=build \
             make build \
               CONFIGS="Debug;RelWithDebInfo" \
               USE_PMM=TRUE \
-              WARNINGS_AS_ERRORS=TRUE \
+              WARNINGS_AS_ERRORS=FALSE \
               BUILD_TESTING=TRUE \
               UNITY_BUILD=TRUE
 
@@ -175,7 +179,7 @@ jobs:
       - name: Prepare Caches
         uses: actions/cache@v4
         with:
-          path: _build/_cache
+          path: _build/.cache
           key: msvc-${{matrix.arch}}
       # This step only warms up the uv cache for the `build` group used by the
       # main build process
@@ -188,4 +192,9 @@ jobs:
         shell: pwsh
         # 17.* selects VS 2022
         run: |
-          tools/ci.ps1 -VSVersion 17.* -TargetArch ${{matrix.arch}} -UseVcpkg -BuildTesting -UnityBuild
+          tools/ci.ps1 -VSVersion 17.* `
+            -TargetArch ${{matrix.arch}} `
+            -VcpkgBinaryCachePath "_build/.cache/vcpkg"
+            -UseVcpkg `
+            -BuildTesting `
+            -UnityBuild

Earthfile

@@ -3,6 +3,10 @@ VERSION 0.8
 # Tweak the default container registry used for pulling system images.
 ARG --global default_container_registry = "docker.io"
 
+# Directory on the host where we will copy in/out cache files. If unset/falsey, then
+# caches will not be persisted on the host, only within the containers
+ARG --global host_cache
+
 init:
     ARG --required env
     # Toggle the building of test programs
@@ -138,21 +142,33 @@ INSTALL_DEPS:
 
     RUN __install $pkgs
 
-    DO +ADD_CCACHE
+    DO +CCACHE_INIT
 
-ADD_CCACHE:
+CCACHE_INIT:
     FUNCTION
     IF ! ccache --version && __can_install ccache
         RUN __install ccache
     END
+    ARG host_cache = false
     IF ccache --version
         ENV CCACHE_DIR = /run/ccache
-        CACHE /run/ccache
         ENV CMAKE_C_COMPILER_LAUNCHER=ccache
         ENV CMAKE_CXX_COMPILER_LAUNCHER=ccache
+
+        IF __bool $host_cache
+            COPY --if-exists $host_cache/ccache $CCACHE_DIR
+        ELSE
+            CACHE $CCACHE_DIR
+        END
+    END
+
+CCACHE_FINISH:
+    FUNCTION
+    IF __bool $host_cache
+        SAVE ARTIFACT $CCACHE_DIR AS LOCAL $host_cache/ccache
     END
 
-VCPKG_SETUP:
+VCPKG_INIT:
     FUNCTION
     # Toggle whether this function actually does anything
     ARG --required use_vcpkg
@@ -163,8 +179,20 @@ VCPKG_SETUP:
         ENV VCPKG_DEFAULT_BINARY_CACHE = "/run/cache/vcpkg/binary"
         # Prepare the area
         RUN mkdir -p $VCPKG_DEFAULT_BINARY_CACHE
-        # Persist that directory between target executions
-        CACHE $VCPKG_DEFAULT_BINARY_CACHE
+        IF __bool $host_cache
+            # We are going to copy in/out caches from the host
+            COPY --if-exists $host_cache/vcpkg $VCPKG_DEFAULT_BINARY_CACHE
+        ELSE
+            # Don't use a host directory, use Earthly's caching volume instead
+            CACHE $VCPKG_DEFAULT_BINARY_CACHE
+        END
+    END
+
+VCPKG_FINISH:
+    FUNCTION
+    ARG --required use_vcpkg
+    IF __bool $use_vcpkg && __bool $host_cache
+        SAVE ARTIFACT $VCPKG_DEFAULT_BINARY_CACHE AS LOCAL $host_cache/vcpkg
     END
 
 COPY_SRC:
@@ -177,9 +205,9 @@ BUILD:
     FUNCTION
     # Enable vcpkg
     ARG --required use_vcpkg
-    DO --pass-args +VCPKG_SETUP
+    DO --pass-args +VCPKG_INIT
     # Enable Ccache caching between container runs
-    DO +ADD_CCACHE
+    DO --pass-args +CCACHE_INIT
 
     ARG install_prefix
     ARG cpack_out
@@ -209,3 +237,6 @@ BUILD:
                     CPACK_OUT="$cpack_out" \
                     PACKAGE_CONFIGS="$configs"
     END
+
+    DO --pass-args +VCPKG_FINISH
+    DO --pass-args +CCACHE_FINISH

tools/__tool

@@ -79,7 +79,7 @@ __alias() {
 }
 
 __bool() {
-    bool=$(printf "%s" "$1" | tr '[:lower:]' '[:upper:]')
+    bool=$(printf "%s" "${1-}" | tr '[:lower:]' '[:upper:]')
     case "$bool" in
         0|OFF|NO|FALSE|N|IGNORE|NOTFOUND|""|*-NOTFOUND)
             return 1;;

tools/ci.ps1

@@ -15,7 +15,9 @@ param(
     [switch]$BuildTesting,
     [switch]$WarningsAsErrors,
     [switch]$Test,
-    [switch]$UnityBuild
+    [switch]$UnityBuild,
+    # Directory where vcpkg will stores its binary caches
+    [string]$VcpkgBinaryCachePath
 )
 
 $ErrorActionPreference = "Stop"
@@ -28,10 +30,13 @@ $this_dir = $PSScriptRoot
 
 $root = Split-Path -Parent $this_dir
 
-# Set the directory where vcpkg will store its binary cache artifacts. This can
-# be persisted between CI runs
-$env:VCPKG_DEFAULT_BINARY_CACHE = "$root/_build/_cache/vcpkg"
-[void](New-Item -ItemType Directory $env:VCPKG_DEFAULT_BINARY_CACHE -Force)
+if (-not [string]::IsNullOrEmpty($VcpkgBinaryCachePath)) {
+    # Set the directory where vcpkg will store its binary cache artifacts. This can
+    # be persisted between CI runs
+    $VcpkgBinaryCachePath = [IO.Path]::GetFullPath($VcpkgBinaryCachePath)
+    $env:VCPKG_DEFAULT_BINARY_CACHE = "$VcpkgBinaryCachePath"
+    [void](New-Item -ItemType Directory $env:VCPKG_DEFAULT_BINARY_CACHE -Force)
+}
 
 Write-Verbose "Loading uv environment..."
 $uv_env = Get-UvEnvironment -ArgumentList "--group=build"