ci/package_core: save and reload build environment

Save the prepared build environment as an artifact after the initial
setup, to allow for multiple jobs to reuse it without repeating the
initial Zephyr configuration steps.

Signed-off-by: Luca Burelli <l.burelli@arduino.cc>

Author: pillo79

.github/workflows/package_core.yml

@@ -6,11 +6,9 @@ on:
 
 jobs:
 
-  package-core:
-    name: Build and package cores
+  build-env:
+    name: Prepare build environment
     runs-on: ubuntu-latest
-    env:
-      CCACHE_IGNOREOPTIONS: -specs=*
     outputs:
       CORE_TAG: ${{ env.CORE_TAG }}
       CORE_HASH: ${{ env.CORE_HASH }}
@@ -46,6 +44,32 @@ jobs:
           echo "ARTIFACTS=$(jq -c '["zephyr"] + (map(.artifact) | unique)' <<< ${ALL_BOARD_DATA})" >> "$GITHUB_ENV"
           echo "SUB_ARCHES=$(jq -c 'map(.subarch) | unique' <<< ${ALL_BOARD_DATA})" >> "$GITHUB_ENV"
 
+          (cd && tar cphf - .cmake work zephyr-sdk-* | zstd > build-env.tar.zstd)
+
+      - name: Archive build environment
+        uses: actions/upload-artifact@v4
+        with:
+          name: build-env
+          path: ~/build-env.tar.zstd
+
+  package-core:
+    name: Build and package cores
+    runs-on: ubuntu-latest
+    needs:
+      - build-env
+    env:
+      CCACHE_IGNOREOPTIONS: -specs=*
+      CORE_TAG: ${{ needs.build-env.outputs.CORE_TAG }}
+    steps:
+      - uses: actions/download-artifact@v4
+        with:
+          path: /home/runner
+          name: build-env
+
+      - name: Restore build environment
+        run: |
+          (cd ~ && tar --use-compress-program=unzstd -xpf build-env.tar.zstd && rm build-env.tar.zstd)
+
       - name: ccache
         uses: hendrikmuhs/ccache-action@v1.2
         with:
@@ -72,13 +96,15 @@ jobs:
   split-core:
     name: Split off ${{ matrix.artifact }}
     runs-on: ubuntu-latest
-    needs: package-core
+    needs:
+      - build-env
+      - package-core
     env:
-      ALL_CORES_ARTIFACT: ArduinoCore-archives-${{ needs.package-core.outputs.CORE_HASH }}
-      CORE_ARTIFACT: ArduinoCore-${{ matrix.artifact }}-${{ needs.package-core.outputs.CORE_HASH }}
+      ALL_CORES_ARTIFACT: ArduinoCore-archives-${{ needs.build-env.outputs.CORE_HASH }}
+      CORE_ARTIFACT: ArduinoCore-${{ matrix.artifact }}-${{ needs.build-env.outputs.CORE_HASH }}
     strategy:
       matrix:
-        artifact: ${{ fromJSON( needs.package-core.outputs.ARTIFACTS ) }}
+        artifact: ${{ fromJSON( needs.build-env.outputs.ARTIFACTS ) }}
     steps:
       - uses: actions/download-artifact@v4
         with:
@@ -93,17 +119,18 @@ jobs:
     name: Test ${{ matrix.subarch }}:${{ matrix.board }}
     runs-on: ubuntu-latest
     needs:
+      - build-env
       - package-core
       - split-core
     strategy:
       matrix:
         include:
-          ${{ fromJSON( needs.package-core.outputs.ALL_BOARD_DATA ) }}
+          ${{ fromJSON( needs.build-env.outputs.ALL_BOARD_DATA ) }}
       fail-fast: false
     env:
       PLAT: arduino:${{ matrix.subarch }}
       FQBN: arduino:${{ matrix.subarch }}:${{ matrix.board }}
-      CORE_ARTIFACT: ArduinoCore-${{ matrix.artifact }}-${{ needs.package-core.outputs.CORE_HASH }}
+      CORE_ARTIFACT: ArduinoCore-${{ matrix.artifact }}-${{ needs.build-env.outputs.CORE_HASH }}
     steps:
       - uses: actions/download-artifact@v4
         with:
@@ -163,18 +190,19 @@ jobs:
       - uses: actions/upload-artifact@v4
         if: ${{ success() || failure() }}
         with:
-          name: test-report-${{ needs.package-core.outputs.CORE_TAG }}-${{ matrix.board }}
+          name: test-report-${{ needs.build-env.outputs.CORE_TAG }}-${{ matrix.board }}
           path: sketches-reports/*
 
   collect-logs:
     name: Collect logs
     runs-on: ubuntu-latest
     needs:
+      - build-env
       - package-core
       - test-core
     if: ${{ !cancelled() && needs.package-core.result == 'success' }}
     env:
-      ALL_BOARD_DATA: ${{ needs.package-core.outputs.ALL_BOARD_DATA }}
+      ALL_BOARD_DATA: ${{ needs.build-env.outputs.ALL_BOARD_DATA }}
     steps:
       - uses: actions/download-artifact@v4
         with:
@@ -230,9 +258,10 @@ jobs:
     runs-on: ubuntu-latest
     if: cancelled() || contains(needs.*.result, 'failure')
     needs:
+      - build-env
       - package-core
       - test-core
-    steps: 
+    steps:
       - name: Notify failure
         run: exit 1
 
@@ -241,14 +270,15 @@ jobs:
     runs-on: ubuntu-latest
     if: ${{ github.event_name == 'push' && github.repository == 'arduino/ArduinoCore-zephyr' }}
     needs:
+      - build-env
       - package-core
       - test-core
     environment: production
     permissions:
       id-token: write
       contents: read
     env:
-      ALL_CORES_ARTIFACT: ArduinoCore-archives-${{ needs.package-core.outputs.CORE_HASH }}
+      ALL_CORES_ARTIFACT: ArduinoCore-archives-${{ needs.build-env.outputs.CORE_HASH }}
     steps:
       - uses: actions/download-artifact@v4
         with:
@@ -271,13 +301,14 @@ jobs:
     runs-on: ubuntu-latest
     if: ${{ github.repository == 'arduino/ArduinoCore-zephyr' }}
     needs:
+      - build-env
       - package-core
       - test-core
     env:
-      ALL_CORES_ARTIFACT: ArduinoCore-archives-${{ needs.package-core.outputs.CORE_HASH }}
-      CORE_TAG: ${{ needs.package-core.outputs.CORE_TAG }}
-      CORE_HASH: ${{ needs.package-core.outputs.CORE_HASH }}
-      ARTIFACTS: ${{ needs.package-core.outputs.ARTIFACTS }}
+      ALL_CORES_ARTIFACT: ArduinoCore-archives-${{ needs.build-env.outputs.CORE_HASH }}
+      CORE_TAG: ${{ needs.build-env.outputs.CORE_TAG }}
+      CORE_HASH: ${{ needs.build-env.outputs.CORE_HASH }}
+      ARTIFACTS: ${{ needs.build-env.outputs.ARTIFACTS }}
     steps:
       - uses: actions/checkout@v4
         with:
@@ -306,6 +337,7 @@ jobs:
   cleanup-artifacts:
     runs-on: ubuntu-latest
     needs:
+      - build-env
       - package-core
       - publish-core
       - publish-json
@@ -314,5 +346,5 @@ jobs:
       - name: Clean up intermediate artifacts
         uses: geekyeggo/delete-artifact@v5.1.0
         with:
-          name: ArduinoCore-archives-${{ needs.package-core.outputs.CORE_HASH }}
+          name: ArduinoCore-archives-${{ needs.build-env.outputs.CORE_HASH }}
           failOnError: false