Added docs and multi platform build

Signed-off-by: Christian Kreuzberger <[email protected]>

README.md

@@ -5,12 +5,77 @@ This repo provides a utility GitHub action for the [CI Workflow](https://github.
 
 ## Inputs
 
-* Todo
+* `IMAGE_NAME` - name of the image (including the docker organization)
+* `DOCKER_FOLDER` (optional, defaults to './') - folder where Dockerfile is in; needs a trailing slash
+* `VERSION` - semantic version used as the tag for the resulting image
+* `DATETIME` (optional) - datetime string, e.g., YYYYMMDDHHmmss; (defaults to `DATETIME=$(date +'%Y%m%d%H%M')`) 
+* `PLATFORMS` (optional) - comma separated list of platforms that the docker image should be build for (e.g., `linux/amd64,linux/arm/v7,linux/arm64`); if set, requires `buildx` to be available (see example below)
 
 ## Outputs
 
-* Todo
+None at the moment
 
 ## Example usage
 
-Todo
+### Simple Example
+
+```
+    env:
+      VERSION: "1.2.3"
+    steps:
+      - name: Checkout Code
+        uses: actions/checkout@v2
+
+      - id: docker_login
+        name: Docker Login
+        uses: docker/login-action@v1
+        with:
+          username: ${{ secrets.REGISTRY_USER }}
+          password: ${{ secrets.REGISTRY_PASSWORD }}
+
+      - id: docker_build
+        name: Docker Build
+        uses: keptn/gh-action-build-docker-image@master
+        with:
+          PLATFORMS: ${{ env.DOCKER_PLATFORMS }}
+          VERSION: ${{ env.VERSION }}
+          IMAGE_NAME: "yourdockerorg/yourimagename"
+```
+
+### Extended Example using buildx
+
+```
+    env:
+      VERSION: "1.2.3"
+    steps:
+      - name: Checkout Code
+        uses: actions/checkout@v2
+
+      - name: Set up QEMU (Docker Multi-Arch Build/BuildX)
+        # needed for docker multi-architecture build
+        uses: docker/setup-qemu-action@v1
+
+      - name: Set up Docker Buildx (Docker Multi-Arch Build/BuildX)
+        # needed for docker multi-architecture build
+        uses: docker/setup-buildx-action@v1
+
+      - id: docker_login
+        name: Docker Login
+        # only run docker login on pushes; also for PRs, but only if this is not a fork
+        if: (github.event_name == 'push') || (github.event.pull_request.head.repo.full_name == github.repository)
+        # note: GH does not allow to access secrets for PRs from a forked repositories due to security reasons
+        # that's fine, but it means we can't push images to dockerhub
+        uses: docker/login-action@v1
+        with:
+          username: ${{ secrets.REGISTRY_USER }}
+          password: ${{ secrets.REGISTRY_PASSWORD }}
+
+      - id: docker_build
+        name: Docker Build
+        uses: keptn/gh-action-build-docker-image@master
+        with:
+          PLATFORMS: "linux/amd64,linux/arm/v7,linux/arm64"
+          VERSION: ${{ env.VERSION }}
+          IMAGE_NAME: "yourdockerorg/yourimagename"
+          DOCKER_FOLDER: "your-sub-directory/"
+```

action.yml

@@ -14,6 +14,9 @@ inputs:
   DATETIME:
     description: Optional datetime for the tag of the docker image (will be set automatically if left empty)
     default: unset
+  PLATFORMS:
+    description: Platform for the docker build (comma separated; requires buildx; leave empty for default)
+    default: ""
 runs:
   using: composite
   steps: 
@@ -71,4 +74,5 @@ runs:
         DOCKER_FOLDER: ${{ inputs.DOCKER_FOLDER }}
         VERSION: ${{ inputs.VERSION }}
         DATETIME: ${{ steps.check_datetime.outputs.DATETIME }}
-      run: ${{ github.action_path }}/build_docker_image.sh "${IMAGE_NAME}" "${DOCKER_FOLDER}" "${VERSION}" "${DATETIME}"
+        PLATFORMS: ${{ inputs.PLATFORMS }}
+      run: ${{ github.action_path }}/build_docker_image.sh "${IMAGE_NAME}" "${DOCKER_FOLDER}" "${VERSION}" "${DATETIME}" "${PLATFORMS}"

build_docker_image.sh

@@ -1,18 +1,19 @@
 #!/bin/bash
 
-if [[ "$#" -ne 4 ]]; then
+if [[ "$#" -le 4 ]]; then
   echo "Usage: $0 IMAGE FOLDER VERSION DATETIME"
-  echo "      Example: $0 keptn/api api/ 1.2.3 20210101101210"
+  echo "      Example: $0 keptn/api api/ 1.2.3 20210101101210 amd64"
   echo "      Your command: $0 $*"
   exit 1
 fi
 
 # todo: not sure if we can use parameters like this
-# ${IMAGE}=$1 ${FOLDER}=$2 ${VERSION}=$3 ${DATETIME}=$4
+# ${IMAGE}=$1 ${FOLDER}=$2 ${VERSION}=$3 ${DATETIME}=$4 ${PLATFORMS}=$5
 IMAGE=$1
 FOLDER=$2
 VERSION=$3
 DATETIME=$4
+PLATFORMS=${5:-""}
 
 # store pwd
 pwd=$(pwd)
@@ -33,10 +34,19 @@ cd ./${FOLDER}
 sed -i '/#travis-uncomment/s/^#travis-uncomment //g' Dockerfile
 sed -i '/#build-uncomment/s/^#build-uncomment //g' Dockerfile
 cat MANIFEST
-docker build . -t "${IMAGE}:${VERSION}.${DATETIME}" -t "${IMAGE}:${VERSION}" --build-arg version="${VERSION}"
+if [[ "$PLATFORMS" != "" ]]; then
+  # use buildx and specify platform
+  echo "PLATFORMS is set to $PLATFORMS, using buildx"
+  DOCKER_BUILD="docker buildx build --platforms \"${PLATFORMS}\""
+else
+  # default build without platforms
+  DOCKER_BUILD="docker build"
+fi
+
+$DOCKER_BUILD . -t "${IMAGE}:${VERSION}.${DATETIME}" -t "${IMAGE}:${VERSION}" --build-arg version="${VERSION}"
 
 if [[ $? -ne 0 ]]; then
-  echo "Failed to build Docker Image ${IMAGE}:${VERSION}.${DATETIME}, exiting"
+  echo "Failed to build Docker Image ${IMAGE}:${VERSION}.${DATETIME} using ${DOCKER_BUILD}, exiting"
   echo "::error file=${FOLDER}/Dockerfile::Failed to build Docker Image"
   exit 1
 fi