Dockerfile

# build the go binary
FROM golang:1.14.4 as builder
WORKDIR /build
COPY go.* ./
RUN go mod download
COPY hello.go .
RUN CGO_ENABLED=0 GOOS=linux GOARCH=amd64 go build -ldflags="-w -s" -o hello .

# build final alpine image
FROM alpine:3.12.0

# allow user and source root to be passed as args at default to sensibles
ARG APP_USER=app
ARG PROJECT_ROOT=/app/

# install required libs
RUN apk update && apk --no-cache --update add ca-certificates

# create app dir and user
RUN mkdir -p ${PROJECT_ROOT} && \
    addgroup -g 1000 ${APP_USER} && \
    adduser -u 1000 -D ${APP_USER} -G ${APP_USER}

# set local directory
WORKDIR ${PROJECT_ROOT}

# copy final go binary from the builder stage
COPY --from=builder /build/hello ${PROJECT_ROOT}hello

# change permissions on our project directory so that our app user has access
RUN chown -R ${APP_USER}:${APP_USER} ${PROJECT_ROOT}

# labels
LABEL maintainer="rob@bitniftee.com"
LABEL copyright="Bitniftee Limited"

# change to our non root user for security purposes
USER ${APP_USER}

# finally expose the port and run the process
EXPOSE 8080
CMD ["./hello"]