Dockerfile

# syntax = docker/dockerfile:1.2

# get modules, if they don't change the cache can be used for faster builds
FROM golang:1.19@sha256:7ffa70183b7596e6bc1b78c132dbba9a6e05a26cd30eaa9832fecad64b83f029 AS base
ENV GO111MODULE=on
ENV CGO_ENABLED=0
ENV GOOS=linux
ENV GOARCH=amd64
WORKDIR /src
COPY go.* .
RUN --mount=type=cache,target=/go/pkg/mod \
    go mod download

# build th application
FROM base AS build
# temp mount all files instead of loading into image with COPY
# temp mount module cache
# temp mount go build cache
RUN --mount=target=. \
    --mount=type=cache,target=/go/pkg/mod \
    --mount=type=cache,target=/root/.cache/go-build \
    go build -ldflags="-w -s" -o /app/main ./cmd/card-guess/*.go

# Import the binary from build stage
FROM gcr.io/distroless/static:nonroot@sha256:ed05c7a5d67d6beebeba19c6b9082a5513d5f9c3e22a883b9dc73ec39ba41c04 as prd
COPY --from=build /app/main /
# this is the numeric version of user nonroot:nonroot to check runAsNonRoot in kubernetes
USER 65532:65532
ENTRYPOINT ["/main"]