Cache and secret mounts in Dockerfile for Go projects

build.sh

#!/bin/sh
git config --global url."https://gitlab-ci-token:${CI_JOB_TOKEN}@gitlab.com".insteadOf "https://gitlab.com"
docker build -t the-app --build-arg "VERSION=${VERSION}" --secret id=gitconfig,src=${HOME}/.gitconfig .

Dockerfile

FROM golang:1.20-bookworm AS builder
WORKDIR /build
ENV \
  GOOS=linux \
  GOARCH=amd64 \
  CGO_ENABLED=0 \
  GOCACHE=/go-build-cache \
  GOMODCACHE=/go-mod-cache
COPY . .
ARG VERSION
RUN \
  --mount=type=secret,id=gitconfig,target=/root/.gitconfig \
  --mount=type=cache,target=/go-mod-cache \
  --mount=type=cache,target=/go-build-cache \
  go build -ldflags "-X 'main.version=${VERSION}'" ./cmd/service

FROM buildpack-deps:bookworm-curl
WORKDIR /app
COPY --from=builder /build/service .
EXPOSE 80
CMD ["./service"]