Split build job and func job

.github/workflows/check.yaml

@@ -67,17 +67,49 @@ jobs:
     - name: Run unit tests
       run: tox -e unit
 
-  func:
+  build:
     needs:
       - lint
       - unit
-    name: functional tests
+    name: build charms
     runs-on: ${{ matrix.runs-on }}
     timeout-minutes: 120
     strategy:
       fail-fast: false
       matrix:
         runs-on: [[ubuntu-22.04]]
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          submodules: true
+
+      - uses: canonical/craft-actions/charmcraft/pack@main
+        id: build
+        with:
+          verbosity: verbose
+          channel: "3.x/stable"
+
+      - name: List the names of the built charms
+        run: echo "${{ steps.build.outputs.charms}}"
+
+      - name: Determine system architecture
+        run: echo "SYSTEM_ARCH=$(uname -m)" >> $GITHUB_ENV
+
+      - name: Upload the tested charms
+        uses: actions/upload-artifact@v4
+        with:
+          name: built_charms_${{ env.SYSTEM_ARCH }}
+          path: ./*.charm
+
+  func:
+    needs:
+      - build
+    name: functional tests
+    runs-on: ubuntu-24.04
+    timeout-minutes: 120
+    strategy:
+      fail-fast: false
+      matrix:
         test-command: ['tox -e func -- -v --series focal', 'tox -e func -- -v --series jammy']
         juju-channel: ["3.4/stable"]
     steps:
@@ -115,15 +147,24 @@ jobs:
           # set default project to be nested-lxd project
           juju model-default project=nested-lxd
 
+      - name: Determine system architecture
+        run: echo "SYSTEM_ARCH=$(uname -m)" >> $GITHUB_ENV
+
         # This is used by zaza in the functional tests for non-amd64 architectures (if applicable)
       - name: Set zaza juju model constraints for architecture
         run: |
-          if [ "$(uname -m)" = "aarch64" ]; then
+          if [ "${{ env.SYSTEM_ARCH }}" = "aarch64" ]; then
             echo "TEST_MODEL_CONSTRAINTS=arch=arm64" >> "$GITHUB_ENV"
           fi
 
-      - name: Build the charm
-        run: charmcraft -v pack
+      - name: Download the built charms
+        uses: actions/download-artifact@v4
+        with:
+          name: built_charms_${{ env.SYSTEM_ARCH }}
+
+      - name: List the names of the downloaded charms
+        run: |
+          ls *.charm
 
       - name: Run tests
         run: |
@@ -142,15 +183,6 @@ jobs:
           TEST_JUJU3: "1"  # https://github.com/openstack-charmers/zaza/pull/653
           TEST_JUJU_CHANNEL: ${{ matrix.juju-channel }}
 
-      - name: Determine system architecture
-        run: echo "SYSTEM_ARCH=$(uname -m)" >> $GITHUB_ENV
-
-      - name: Upload the tested charms
-        uses: actions/upload-artifact@v4
-        with:
-          name: charm_${{ env.SYSTEM_ARCH }}
-          path: ./*.charm
-
       # Save output for debugging
 
       - name: Generate debugging information