Added a multi-stage Dockerfile for easier local image builds

.dockerignore

@@ -0,0 +1,7 @@
+Dockerfile*
+.git/**
+dist/**
+.goreleaser.yml
+.github/**
+docs/**
+README*

.goreleaser.yml

@@ -43,6 +43,7 @@ snapshot:
 dockers:
   - image_templates:
       - "itzg/{{ .ProjectName }}:{{ .Version }}-amd64"
+    dockerfile: Dockerfile.release
     goarch: amd64
     build_flag_templates:
       - --platform
@@ -53,6 +54,7 @@ dockers:
 
   - image_templates:
       - "itzg/{{ .ProjectName }}:{{ .Version }}-arm64"
+    dockerfile: Dockerfile.release
     goarch: arm64
     build_flag_templates:
       - --platform
@@ -62,6 +64,7 @@ dockers:
       - --label=org.opencontainers.image.revision={{ .FullCommit }}
   - image_templates:
       - "itzg/{{ .ProjectName }}:{{ .Version }}-arm32v6"
+    dockerfile: Dockerfile.release
     goarch: arm
     goarm: "6"
     build_flag_templates:

Dockerfile

@@ -1,8 +1,13 @@
+FROM golang:1.17 as builder
+
+WORKDIR /build
+
+COPY go.mod go.sum ./
+RUN go mod download
+
+COPY . .
+RUN CGO_ENABLED=0 go build ./cmd/mc-router
+
 FROM scratch
-
-LABEL org.opencontainers.image.authors="Geoff Bourne <itzgeoff@gmail.com>"
-LABEL org.opencontainers.image.title="mc-router"
-LABEL org.opencontainers.image.source="https://github.com/itzg/mc-router"
-
-COPY mc-router /
 ENTRYPOINT ["/mc-router"]
+COPY --from=builder /build/mc-router /mc-router

Dockerfile.release

@@ -0,0 +1,8 @@
+FROM scratch
+
+LABEL org.opencontainers.image.authors="Geoff Bourne <itzgeoff@gmail.com>"
+LABEL org.opencontainers.image.title="mc-router"
+LABEL org.opencontainers.image.source="https://github.com/itzg/mc-router"
+
+COPY mc-router /
+ENTRYPOINT ["/mc-router"]

README.md

@@ -165,11 +165,7 @@ kubectl apply -f https://raw.githubusercontent.com/itzg/mc-router/master/docs/k8
 ## Building locally with Docker
 
 ```bash
-docker run -it --rm \
-  -v gopkg:/go/pkg \
-  -v ${PWD}:/build -w /build \
-  golang:1.17.3 \
-  go build ./cmd/mc-router
+docker build -t mc-router .
 ```
 
 ## Skaffold