Jenkins and RVM with Ruby 2.2.3 - Docker image

jenkins_rvm.Dockerfile

# v1.0
# November 21, 2015

FROM jenkins:latest
MAINTAINER NickGnd "nick.gnd@gmail.com"
# https://github.com/jenkinsci/docker/blob/4fa9ebc13069fa8186728622cd63702cddf11162/Dockerfile

ENV RUBY_VERSION 2.2.3

# --handlerCountStartup    = set the no of worker threads to spawn at startup. Default is 5
# --handlerCountMax        = set the max no of worker threads to allow. Default is 300
# --handlerCountMaxIdle    = set the max no of idle worker threads to allow. Default is 50
ENV JENKINS_OPTS="--handlerCountStartup=5 --handlerCountMax=100 --logfile=/var/log/jenkins/jenkins.log"
ENV PATH $PATH:/usr/local/rvm/bin

# Add custom bashrc
RUN rm /var/jenkins_home/.bashrc
ADD ./utils/bashrc_rvm /var/jenkins_home/.bashrc

USER root

# change default bash
RUN rm /bin/sh && ln -s /bin/bash /bin/sh

# Install essentials packages
# RUN apt-get update && apt-get install DEBIAN_FRONTEND=noninteractive install -yq build-essential curl gnupg git vim

RUN apt-get update -q \
    && DEBIAN_FRONTEND=noninteractive apt-get install -yq --no-install-recommends \
      build-essential \
      curl \
      gnupg \
      git \
      vim

# Install mysql client (no server)
RUN DEBIAN_FRONTEND=noninteractive apt-get install -yq mysql-client libmysqlclient-dev

# Download RVM as root
RUN curl -#LO https://rvm.io/mpapis.asc && gpg --import mpapis.asc
RUN \curl -sSL https://get.rvm.io | bash -s stable

# Install RVM requirements
RUN /bin/bash -lc "rvm requirements"


# Add jenkins to rvm group
RUN usermod -a -G rvm jenkins

USER jenkins

# Install Ruby
RUN /bin/bash -lc  "rvm install $RUBY_VERSION && rvm use $RUBY_VERSION --default"

# Set no doc for gem
RUN echo "gem: --no-rdoc --no-ri" >> ~/.gemrc

# Install bundler
RUN /bin/bash -lc  "gem install bundler --no-doc --no-ri"

# Jenkins home directoy is a volume, so configuration and build history
# can be persisted and survive image upgrades
VOLUME /var/jenkins_home

USER root

RUN chown -R jenkins /var/jenkins_home

# Add Jenkins Log folder
RUN mkdir /var/log/jenkins \
    && touch /var/log/jenkins/jenkins.log \
    && chown -R  jenkins:jenkins /var/log/jenkins

# slim down image
RUN apt-get clean && rm -rf /var/lib/apt/lists/* /tmp/* /var/tmp/* /usr/share/man/?? /usr/share/man/??_*

# Already exposed 8080 & 50000 ports in Jenkins image