Caddy cross-platform Docker build

Dockerfile

FROM --platform=${BUILDPLATFORM} golang:1.14 AS build

ARG TARGETOS
ARG TARGETARCH
ARG caddy_version=v1.0.4

ENV GOOS=${TARGETOS}
ENV GOARCH=${TARGETARCH}
WORKDIR /usr/local/src/caddy
COPY ./main.go ./

RUN go mod init caddy && \
  go get github.com/caddyserver/caddy@${caddy_version} && \
  go build

FROM busybox:1.31-glibc

COPY --from=build /usr/local/src/caddy/caddy /usr/local/bin/caddy

CMD ["/usr/local/bin/caddy"]

main.go

package main

import (
	"github.com/caddyserver/caddy/caddy/caddymain"
)

func main() {
	caddymain.Run()
}