Create a hello world image to be used by the docs (#5550)

.github/workflows/knative-mkdocs-dockerimage.yaml

@@ -1,4 +1,4 @@
-name: Docker Image CI
+name: Build Images
 
 on:
   push:
@@ -6,7 +6,7 @@ on:
 
 jobs:
   build-and-push-image:
-    name: Build knative mkdocs dockerfile
+    name: Build Knative Images
     runs-on: ubuntu-latest
     permissions:
       contents: read
@@ -15,6 +15,9 @@ jobs:
       - name: Checkout repository
         uses: actions/checkout@v2
 
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v2
+
       - name: Log in to the Container registry
         uses: docker/login-action@v1
         with:
@@ -22,9 +25,17 @@ jobs:
           username: ${{ github.actor }}
           password: ${{ secrets.GITHUB_TOKEN }}
 
-      - name: Build and push docker image
-        uses: docker/build-push-action@v2
+      - name: Build mkdocs image
+        uses: docker/build-push-action@v4
         with:
           push: true
           file: ./hack/docker/Dockerfile
           tags: ghcr.io/knative/knative-docs:latest
+
+      - name: Build helloworld-go image
+        uses: docker/build-push-action@v4
+        with:
+          push: true
+          platforms: linux/amd64,linux/arm64
+          context: ./code-samples/serving/hello-world/helloworld-go
+          tags: ghcr.io/knative/helloworld-go:latest

code-samples/serving/hello-world/helloworld-go/Dockerfile

@@ -1,6 +1,9 @@
 # Use the official Golang image to create a build artifact.
 # This is based on Debian and sets the GOPATH to /go.
-FROM golang:1.13 as builder
+FROM golang:latest as builder
+
+ARG TARGETOS
+ARG TARGETARCH
 
 # Create and change to the app directory.
 WORKDIR /app
@@ -15,7 +18,7 @@ COPY . ./
 
 # Build the binary.
 # -mod=readonly ensures immutable go.mod and go.sum in container builds.
-RUN CGO_ENABLED=0 GOOS=linux go build -mod=readonly -v -o server
+RUN CGO_ENABLED=0 GOOS=${TARGETOS} GOARCH=${TARGETARCH} go build -mod=readonly -v -o server
 
 # Use the official Alpine image for a lean production container.
 # https://hub.docker.com/_/alpine

code-samples/serving/hello-world/helloworld-go/README.md

@@ -65,7 +65,10 @@ Navigate to your project directory and copy the following code into a new file n
 ```dockerfile
 # Use the official Golang image to create a build artifact.
 # This is based on Debian and sets the GOPATH to /go.
-FROM golang:1.13 as builder
+FROM golang:latest as builder
+
+ARG TARGETOS
+ARG TARGETARCH
 
 # Create and change to the app directory.
 WORKDIR /app
@@ -80,7 +83,7 @@ COPY . ./
 
 # Build the binary.
 # -mod=readonly ensures immutable go.mod and go.sum in container builds.
-RUN CGO_ENABLED=0 GOOS=linux go build -mod=readonly -v -o server
+RUN CGO_ENABLED=0 GOOS=${TARGETOS} GOARCH=${TARGETARCH} go build -mod=readonly -v -o server
 
 # Use the official Alpine image for a lean production container.
 # https://hub.docker.com/_/alpine