Parameterize Docker image build

This will enable keen users who can build Contour themselves to use a different golang image to support building with FIPS-validated BoringCrypto library.

Updates projectcontour#2878

Signed-off-by: Sunjay Bhatia <[email protected]>

Dockerfile

@@ -1,6 +1,7 @@
 ARG BUILDPLATFORM=linux/amd64
+ARG BUILD_BASE_IMAGE
 
-FROM --platform=$BUILDPLATFORM golang:1.15.8 AS build
+FROM --platform=$BUILDPLATFORM $BUILD_BASE_IMAGE AS build
 WORKDIR /contour
 
 ENV GOPROXY=https://proxy.golang.org
@@ -16,11 +17,12 @@ COPY Makefile Makefile
 ARG BUILD_BRANCH
 ARG BUILD_SHA
 ARG BUILD_VERSION
+ARG BUILD_CGO_ENABLED
 ARG TARGETOS
 ARG TARGETARCH
 
 RUN make build \
-	    CGO_ENABLED=0 \
+	    CGO_ENABLED=${BUILD_CGO_ENABLED}} \
 		GOOS=${TARGETOS} \
 		GOARCH=${TARGETARCH} \
 	    BUILD_VERSION=${BUILD_VERSION} \

Makefile

@@ -29,6 +29,12 @@ endif
 # Platforms to build the multi-arch image for.
 IMAGE_PLATFORMS ?= linux/amd64,linux/arm64
 
+# Base build image to use.
+BUILD_BASE_IMAGE ?= golang:1.15.8
+
+# Enable build with CGO.
+BUILD_CGO_ENABLED ?= 0
+
 # Used to supply a local Envoy docker container an IP to connect to that is running
 # 'contour serve'. On MacOS this will work, but may not on other OSes. Defining
 # LOCALIP as an env var before running 'make local' will solve that.
@@ -99,19 +105,23 @@ download: ## Download Go modules
 multiarch-build-push: ## Build and push a multi-arch Contour container image to the Docker registry
 	docker buildx build \
 		--platform $(IMAGE_PLATFORMS) \
+		--build-arg "BUILD_BASE_IMAGE=$(BUILD_BASE_IMAGE)" \
 		--build-arg "BUILD_VERSION=$(BUILD_VERSION)" \
 		--build-arg "BUILD_BRANCH=$(BUILD_BRANCH)" \
 		--build-arg "BUILD_SHA=$(BUILD_SHA)" \
+		--build-arg "BUILD_CGO_ENABLED=$(BUILD_CGO_ENABLED)" \
 		$(DOCKER_BUILD_LABELS) \
 		$(IMAGE_TAGS) \
 		--push \
 		.
 
 container: ## Build the Contour container image
 	docker build \
+		--build-arg "BUILD_BASE_IMAGE=$(BUILD_BASE_IMAGE)" \
 		--build-arg "BUILD_VERSION=$(BUILD_VERSION)" \
 		--build-arg "BUILD_BRANCH=$(BUILD_BRANCH)" \
 		--build-arg "BUILD_SHA=$(BUILD_SHA)" \
+		--build-arg "BUILD_CGO_ENABLED=$(BUILD_CGO_ENABLED)" \
 		$(DOCKER_BUILD_LABELS) \
 		$(shell pwd) \
 		--tag $(IMAGE):$(VERSION)