Use NFS cache as a mirror only

Change-type: minor
Signed-off-by: Kyle Harding <[email protected]>

.github/workflows/yocto-build-deploy.yml

@@ -186,10 +186,6 @@ jobs:
       automation_dir: "${{ github.workspace }}/balena-yocto-scripts/automation"
       BALENARC_BALENA_URL: ${{ vars.BALENA_HOST || inputs.deploy-environment || 'balena-cloud.com' }}
       API_ENV: ${{ vars.BALENA_HOST || inputs.deploy-environment || 'balena-cloud.com' }}
-
-      # Yocto NFS sstate cache host
-      YOCTO_CACHE_HOST: ${{ vars.YOCTO_CACHE_HOST || 'nfs.product-os.io' }}
-      YOCTO_CACHE_DIR: ${{ github.workspace }}/shared/yocto-cache
       BARYS_ARGUMENTS_VAR: ""
 
     outputs:
@@ -446,17 +442,34 @@ jobs:
           BARYS_ARGUMENTS_VAR="${BARYS_ARGUMENTS_VAR} --bitbake-args --no-setscene"
           echo "BARYS_ARGUMENTS_VAR=${BARYS_ARGUMENTS_VAR}" >>"${GITHUB_ENV}"
 
-      # the directory is required even if we don't mount the NFS share
-      - name: Create shared cache mount point
-        run: |
-          sudo mkdir -p "${YOCTO_CACHE_DIR}/$(whoami)"
-          sudo chown -R "$(id -u):$(id -g)" "${YOCTO_CACHE_DIR}"
-
+      # https://wiki.yoctoproject.org/wiki/Enable_sstate_cache
+      # https://docs.yoctoproject.org/4.0.10/ref-manual/variables.html#term-MIRRORS
+      # https://docs.yoctoproject.org/4.0.10/ref-manual/variables.html#term-PREMIRRORS
+      # https://docs.yoctoproject.org/4.0.10/ref-manual/variables.html#term-SSTATE_MIRRORS
       - name: Mount shared NFS cache
-        if: env.YOCTO_CACHE_HOST != '' && contains(fromJSON(inputs.build-runs-on), 'self-hosted')
+        if: vars.YOCTO_CACHE_HOST && contains(fromJSON(inputs.build-runs-on), 'self-hosted')
+        # continue-on-error: true
+        env:
+          YOCTO_CACHE_HOST: ${{ vars.YOCTO_CACHE_HOST }}
+          MOUNTPOINT: /nfs/yocto
         run: |
-          sudo mount -t nfs "${YOCTO_CACHE_HOST}:/" "${YOCTO_CACHE_DIR}" -o fsc,nolock
-          ls -al "${YOCTO_CACHE_DIR}/$(whoami)"
+          sudo mkdir -p "${MOUNTPOINT}"
+          sudo chown -R "$(id -u):$(id -g)" "${MOUNTPOINT}"
+          sudo mount -t nfs "${YOCTO_CACHE_HOST}:/" "${MOUNTPOINT}" -o fsc,nolock
+
+          mkdir -p conf
+          cat <<EOF >> conf/auto.conf
+          SSTATE_MIRRORS:prepend = "
+            file://.* file://${MOUNTPOINT}/$(whoami)/${MACHINE}/sstate/PATH"
+
+          PREMIRRORS:prepend = "
+            git://.*/.* file://${MOUNTPOINT}/$(whoami)/shared-downloads/
+            ftp://.*/.* file://${MOUNTPOINT}/$(whoami)/shared-downloads/
+            http://.*/.* file://${MOUNTPOINT}/$(whoami)/shared-downloads/
+            https://.*/.* file://${MOUNTPOINT}/$(whoami)/shared-downloads/"
+
+          BB_NO_NETWORK=1
+          EOF
 
       # All preperation complete before this step
       # Start building balenaOS
@@ -466,6 +479,7 @@ jobs:
         id: build
         env:
           HELPER_IMAGE_REPO: ghcr.io/balena-os/balena-yocto-scripts
+          SHARED_BUILD_DIR: ${{ github.workspace }}/shared
         run: |
           # When building for non-x86 device types, meson, after building binaries must try to run them via qemu if possible , maybe as some sanity check or test?
           # Therefore qemu must be used - and our runner mmap_min_addr is set to 4096 (default, set here: https://github.com/product-os/github-runner-kernel/blob/ef5a66951599dc64bf2920d896c36c6d9eda8df6/config/5.10/microvm-kernel-x86_64-5.10.config#L858
@@ -475,10 +489,14 @@ jobs:
           sudo sysctl -w vm.mmap_min_addr=65536
           sysctl vm.mmap_min_addr
 
+          mkdir -p "${SHARED_BUILD_DIR}"
+
+          cat conf/auto.conf
+
           ./balena-yocto-scripts/build/balena-build.sh \
             -d "${MACHINE}" \
             -t "${{ secrets.BALENA_API_DEPLOY_KEY }}" \
-            -s "${YOCTO_CACHE_DIR}/$(whoami)" \
+            -s "${SHARED_BUILD_DIR}" \
             -g "${BARYS_ARGUMENTS_VAR}"
 
           if grep -R "ERROR: " build/tmp/log/*; then