ci: Cache source files

This commit updates the CI workflow to cache the crosstool-ng and poky
source files used for building the Zephyr SDK in the AWS S3, in order
to speed up the builds as well as to improve the availability of the
source files.

Signed-off-by: Stephanos Ioannidis <[email protected]>

Author: stephanosio

.github/workflows/ci.yml

@@ -525,6 +525,29 @@ jobs:
         name: version
         path: ${{ runner.temp }}
 
+    - name: Configure AWS Credentials
+      uses: aws-actions/configure-aws-credentials@v1
+      with:
+        aws-access-key-id: ${{ secrets.AWS_CACHE_SDK_ACCESS_KEY_ID }}
+        aws-secret-access-key: ${{ secrets.AWS_CACHE_SDK_SECRET_ACCESS_KEY }}
+        aws-region: us-east-1
+
+    - name: Download cached source files
+      continue-on-error: true
+      run: |
+        SRC_CACHE_BASE="s3://cache-sdk/crosstool-ng-sources"
+        SRC_CACHE_DIR="${{ matrix.host.name }}/${{ matrix.target }}"
+        SRC_CACHE_URI="${SRC_CACHE_BASE}/${SRC_CACHE_DIR}"
+
+        # Download cached source files
+        mkdir -p ${WORKSPACE}/sources
+        pushd ${WORKSPACE}/sources
+        aws s3 sync ${SRC_CACHE_URI} .
+        popd
+
+        # Export environment variables
+        echo "SRC_CACHE_URI=${SRC_CACHE_URI}" >> $GITHUB_ENV
+
     - name: Build toolchain
       run: |
         # Set output path
@@ -694,6 +717,13 @@ jobs:
         md5sum ${ARCHIVE_FILE} > md5.sum
         sha256sum ${ARCHIVE_FILE} > sha256.sum
 
+    - name: Sync downloaded source files to cache
+      continue-on-error: true
+      run: |
+        pushd ${WORKSPACE}/sources
+        aws s3 sync . ${SRC_CACHE_URI}
+        popd
+
     - name: Prepare toolchain build log
       if: always()
       run: |
@@ -761,10 +791,37 @@ jobs:
         submodules: recursive
         persist-credentials: false
 
+    - name: Configure AWS Credentials
+      uses: aws-actions/configure-aws-credentials@v1
+      with:
+        aws-access-key-id: ${{ secrets.AWS_CACHE_SDK_ACCESS_KEY_ID }}
+        aws-secret-access-key: ${{ secrets.AWS_CACHE_SDK_SECRET_ACCESS_KEY }}
+        aws-region: us-east-1
+
+    - name: Download cached source files (Linux)
+      if: startsWith(matrix.host.name, 'linux-')
+      continue-on-error: true
+      run: |
+        SRC_CACHE_BASE="s3://cache-sdk/poky-sources"
+        SRC_CACHE_DIR="${{ matrix.host.name }}"
+        SRC_CACHE_URI="${SRC_CACHE_BASE}/${SRC_CACHE_DIR}"
+        POKY_DOWNLOADS="${RUNNER_TEMP}/poky-downloads"
+
+        # Download cached source files
+        mkdir -p ${POKY_DOWNLOADS}
+        pushd ${POKY_DOWNLOADS}
+        aws s3 sync ${SRC_CACHE_URI} .
+        popd
+
+        # Export environment variables
+        echo "SRC_CACHE_URI=${SRC_CACHE_URI}" >> $GITHUB_ENV
+        echo "POKY_DOWNLOADS=${POKY_DOWNLOADS}" >> $GITHUB_ENV
+
     - name: Build Linux host tools
       if: startsWith(matrix.host.name, 'linux-')
       run: |
         POKY_BASE=${GITHUB_WORKSPACE}/meta-zephyr-sdk
+        export META_DOWNLOADS="${POKY_DOWNLOADS}"
 
         # Check out Poky
         ${POKY_BASE}/scripts/meta-zephyr-sdk-clone.sh
@@ -796,6 +853,16 @@ jobs:
         md5sum ${ARCHIVE_FILE} > md5.sum
         sha256sum ${ARCHIVE_FILE} > sha256.sum
 
+    - name: Sync downloaded source files to cache (Linux)
+      if: startsWith(matrix.host.name, 'linux-')
+      continue-on-error: true
+      run: |
+        pushd ${POKY_DOWNLOADS}
+        rm -rf git2
+        rm -rf svn
+        aws s3 sync . ${SRC_CACHE_URI}
+        popd
+
     - name: Upload toolchain build artifact
       if: startsWith(matrix.host.name, 'linux-') # FIXME: Do for all
       uses: actions/upload-artifact@v2