Adapt image to multi-arch arm,amd (#7)

* Multi-arch build

* clean before build, as --manifest is additive

Author: hash-d

Dockerfile

@@ -1,13 +1,15 @@
-FROM golang:1.15-alpine AS builder
+FROM --platform=$BUILDPLATFORM golang:1.15-alpine AS builder
+
+ARG TARGETOS
+ARG TARGETARCH
+
 RUN mkdir /build
 ADD . /build
 WORKDIR /build
-RUN go build -o tcp-go-echo .
+RUN GOOS=$TARGETOS GOARCH=$TARGETARCH go build -o tcp-go-echo .
 
-
-FROM alpine
+FROM --platform=$TARGETPLATFORM alpine
 RUN mkdir /app
 WORKDIR /app
 COPY --from=builder /build/tcp-go-echo /app
 CMD ["/app/tcp-go-echo"]
-

Makefile

@@ -0,0 +1,21 @@
+
+IMAGE_NAME = quay.io/skupper/tcp-go-echo
+PLATFORM = linux/amd64,linux/arm64
+
+# The option below creates the images in the docker format.
+# That is required for their use with Openshift 3.11
+FORMAT_OPTIONS = --format docker
+
+.DEFAULT_GOAL := build
+
+build: clean
+	podman build --no-cache --platform $(PLATFORM) --manifest $(IMAGE_NAME) $(FORMAT_OPTIONS) .
+
+push:
+	podman manifest push $(IMAGE_NAME)
+
+clean:
+	-podman manifest rm $(IMAGE_NAME)
+
+check:
+	podman manifest inspect $(IMAGE_NAME)