Dockerfile for multistage build of the go-url-shortener app.

Dockefile.dockerfile

# build image
FROM centos:7 as builder
LABEL author="Xavier Coulon"
ENV LANG=en_US.utf8

# Install wget and git
RUN yum  --enablerepo=centosplus install -y \
    wget \
    git

# install golang 1.9
ENV GOLANG_VERSION=1.9.2
RUN wget -O /opt/go${GOLANG_VERSION}.linux-amd64.tar.gz https://storage.googleapis.com/golang/go${GOLANG_VERSION}.linux-amd64.tar.gz && \
    tar -C /usr/local -xzf /opt/go${GOLANG_VERSION}.linux-amd64.tar.gz 
ENV PATH=$PATH:/usr/local/go/bin
ENV GOPATH=/go

# install glide for Go package management
RUN cd /tmp \
    && wget https://github.com/Masterminds/glide/releases/download/v0.12.3/glide-v0.12.3-linux-amd64.tar.gz \
    && tar xvzf glide-v*.tar.gz \
    && mv linux-amd64/glide /usr/bin \
    && rm -rfv glide-v* linux-amd64 

# import source from host
ADD . /go/src/github.com/xcoulon/go-url-shortener
WORKDIR /go/src/github.com/xcoulon/go-url-shortener
RUN glide install 
# run the tests, using build args to specify the connection settings to the Postgres DB
# optional args that can be filled with `build-arg` when executing the `docker build` command
ARG POSTGRES_HOST
ARG POSTGRES_PORT
ARG POSTGRES_USER
ARG POSTGRES_PASSWORD
RUN LOG_LEVEL=debug go test ./...
# build the application
RUN go build -o bin/go-url-shortener

# final image
FROM centos:7

# Add the binary file generated in the `builder` container above
COPY --from=builder /go/src/github.com/xcoulon/go-url-shortener/bin/go-url-shortener /usr/local/bin/go-url-shortener

# Create a non-root user and a group with the same name: "shortenerapp"
ENV USER_GROUP=shortenerapp
RUN groupadd -r ${USER_GROUP} && \
    useradd --no-create-home -g ${USER_GROUP} ${USER_GROUP} 
# From here onwards, any RUN, CMD, or ENTRYPOINT will be run under the following user instead of 'root'
USER ${USER_GROUP} 

EXPOSE 8080

ENTRYPOINT [ "/usr/local/bin/go-url-shortener" ]