Multi stage build in Docker example.md

tags: dev4devs

Example of multi stage build for Docker images

# Base image Example

# ----------------
#############################################
# Temp image to build the prerequisites 
#############################################
FROM registry.access.redhat.com/ubi8/ubi:latest AS builder

RUN groupadd -g 1001 appuser && \
useradd -m -s /sbin/nologin -u 1001 -g appuser appuser

#############################################
# Container Image
#############################################
FROM registry.access.redhat.com/ubi8/ubi-minimal:latest
MAINTAINER Dev4Devs <dev4devs@gmail.com>

# Define Labels
LABEL name="my.dev4devs-com/docker-multi-stages-build-image" \
maintainer="dev4devs@gmail.com" \
vendor="Dev4Devs" 

# Define EnvVars
ENV APP=/usr/local/bin/app \
USER_UID=1001 \
USER_NAME=appuser \
USER_HOME=/home/appuser 

# Copy group and user created in the builder image
COPY --from=builder /etc/passwd /tmp
COPY --from=builder /etc/group /tmp

# Create the user and group in this image and add permissions 
RUN cat /tmp/passwd | grep ${USER_NAME} >> /etc/passwd \
&& cat /tmp/group | grep ${USER_NAME} >> /etc/group \
&& mkdir -p ${USER_HOME} \
&& chown -R ${USER_NAME}:${USER_NAME} ${USER_HOME} \
&& chmod ug+rwx ${USER_HOME} \
&& rm -rf /tmp/passwd \
&& rm -rf /tmp/group

# Use the user created to run the container as rootless
USER ${USER_UID}

# Installs the operator binary
COPY build/_output/bin/${USER_NAME} ${PROXY}
COPY build/bin /usr/local/bin

# This allows the Platform to validate the authority the image
# More info: https://docs.openshift.com/container-platform/3.11/creating_images/guidelines.html#openshift-specific-guidelines
ENTRYPOINT ["/usr/local/bin/entrypoint"]

# Execute the operator 
CMD exec ${APP} $@