Dockerfile

############################
# STEP 1 build executable binary
############################
FROM golang:alpine as builder

# Install git + SSL ca certificates.`
# Git is required for fetching the dependencies.
# Ca-certificates is required to call HTTPS endpoints.
RUN apk update \
    && \
    apk add \
    --no-cache \
    git=2.30.0-r0  \
    ca-certificates=20191127-r5 \
    tzdata=2020f-r0 \
    && \
    update-ca-certificates

# Create appuser
ENV USER=appuser
ENV UID=10001

# See https://stackoverflow.com/a/55757473/12429735
RUN adduser \
    --disabled-password \
    --gecos "" \
    --home "/nonexistent" \
    --shell "/sbin/nologin" \
    --no-create-home \
    --uid "${UID}" \
    "${USER}"
WORKDIR $GOPATH/src/mypackage/myapp/

# use modules
COPY cmd/module/go.mod .

ENV GO111MODULE=on
RUN go mod download
RUN go mod verify

COPY cmd/module/ .

# Build the binary
RUN CGO_ENABLED=0 GOOS=linux GOARCH=amd64 go build \
    -ldflags='-w -s -extldflags "-static"' -a \
    -o /go/bin/module .

############################
# STEP 2 build a small image
############################
FROM scratch

# Import from builder.
COPY --from=builder /usr/share/zoneinfo /usr/share/zoneinfo
COPY --from=builder /etc/ssl/certs/ca-certificates.crt /etc/ssl/certs/
COPY --from=builder /etc/passwd /etc/passwd
COPY --from=builder /etc/group /etc/group

# Copy our static executable
COPY --from=builder /go/bin/module /go/bin/module

# Use an unprivileged user.
USER appuser:appuser

# Run the module binary.
ENTRYPOINT ["/go/bin/module"]