CI: Add step to build Raspberry Pi3 image using the built Docker image

.github/workflows/build.yml

@@ -9,4 +9,6 @@ jobs:
     - name: Checkout
       uses: actions/checkout@master
     - name: Build Docker image
-      run: docker build .
+      run: docker-compose build buildroot
+    - name: Test Docker image
+      run: docker-compose run buildroot

.github/workflows/raspberrypi3_test_defconfig

@@ -0,0 +1,22 @@
+BR2_arm=y
+BR2_cortex_a53=y
+BR2_ARM_FPU_NEON_VFPV4=y
+BR2_TOOLCHAIN_EXTERNAL=y
+BR2_SYSTEM_DHCP="eth0"
+BR2_ROOTFS_POST_BUILD_SCRIPT="board/raspberrypi3/post-build.sh"
+BR2_ROOTFS_POST_IMAGE_SCRIPT="board/raspberrypi3/post-image.sh"
+BR2_ROOTFS_POST_SCRIPT_ARGS="--add-pi3-miniuart-bt-overlay"
+BR2_LINUX_KERNEL=y
+BR2_LINUX_KERNEL_CUSTOM_TARBALL=y
+BR2_LINUX_KERNEL_CUSTOM_TARBALL_LOCATION="$(call github,raspberrypi,linux,83b36f98e1a48d143f0b466fcf9f8c4e382c9a1c)/linux-83b36f98e1a48d143f0b466fcf9f8c4e382c9a1c.tar.gz"
+BR2_LINUX_KERNEL_DEFCONFIG="bcm2709"
+BR2_LINUX_KERNEL_DTS_SUPPORT=y
+BR2_LINUX_KERNEL_INTREE_DTS_NAME="bcm2710-rpi-3-b bcm2710-rpi-3-b-plus bcm2710-rpi-cm3"
+BR2_PACKAGE_RPI_FIRMWARE=y
+BR2_TARGET_ROOTFS_EXT2=y
+BR2_TARGET_ROOTFS_EXT2_4=y
+BR2_TARGET_ROOTFS_EXT2_SIZE="120M"
+# BR2_TARGET_ROOTFS_TAR is not set
+BR2_PACKAGE_HOST_DOSFSTOOLS=y
+BR2_PACKAGE_HOST_GENIMAGE=y
+BR2_PACKAGE_HOST_MTOOLS=y

README.md

@@ -38,3 +38,10 @@ docker run -ti -e BR2_EXTERNAL=/mycustombuildroot -v `pwd`:/mycustombuildroot si
 ```
 
 Now you can issue your regular buildroot commands, like `make menuconfig` or `make <boardname>_defconfig` followed by `make`.
+
+## Development
+### Building the image
+Either simply issue `docker build -t <name> .` or alternatively use the included Docker Compose file using `docker-compose build buildroot`.
+
+### Testing
+To validate that the image works correctly a simple test that builds a Raspberry Pi3 image using the default external toolchain can be run using the included Docker Compose file `docker-compose run --rm buildroot`.

docker-compose.yml

@@ -0,0 +1,7 @@
+version: "2.4"
+services:
+  buildroot:
+    build: .
+    volumes:
+      - ./.github/workflows/raspberrypi3_test_defconfig:/buildroot/configs/raspberrypi3_test_defconfig
+    command: sh -c "make raspberrypi3_test_defconfig && make"