CentOS 6 Linux Base Docker Image


CentOS 6 Linux Docker


For more information on Docker, visit docker.com


Description:


This instruction set will show how to build a base container image using CentOS Linux 6. This container image is the image used for many of the appcontainers images found on the docker hub.


CentOS 6 Linux Base Minimal Install - 136 MB (tags: latest, 6) CentOS 6 Linux Base with Ansible - 188 MB (tags: ansible, ansible-6)

This container is built from centos:6.9, (393/445 MB Before Flatification)


Installation Steps:


Install official CentOS 6 GPG Key:

rpm --import /etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6


Install the Epel Repository:

yum install -y epel-release
rpm --import http://download.fedoraproject.org/pub/epel/RPM-GPG-KEY-EPEL-6

s

Install the Remi Repository:

cd /etc/yum.repos.d/;
curl -O http://rpms.famillecollet.com/enterprise/remi-release-6.rpm;
rpm -Uvh remi-release-6*.rpm;
rpm --import /etc/pki/rpm-gpg/RPM-GPG-KEY-remi
rm -fr *.rpm


Modify Remi Repo to enable remi base and PHP 7.1:

sed -ie '/\[remi\]/,/^\[/s/enabled=0/enabled=1/' /etc/yum.repos.d/remi.repo;
sed -ie '/\[remi-php71\]/,/^\[/s/enabled=0/enabled=1/' /etc/yum.repos.d/remi-php71.repo


Update the OS and install required packages:

yum clean all;
yum -y update;

The following packages are also installed on the :ansible variant only

yum update ansible


The following configuration is also set on the ansible variant only

curl "https://bootstrap.pypa.io/get-pip.py" -o "/tmp/get-pip.py" && \
python /tmp/get-pip.py && \
pip install pip --upgrade && \
rm -fr /tmp/get-pip.py && \
mkdir -p /etc/ansible/roles || exit 0 && \
echo localhost ansible_connection=local > /etc/ansible/hosts
mkdir -p /etc/ansible/roles || exit 0 && \
echo localhost ansible_connection=local > /etc/ansible/hosts


Cleanup:

Remove the contents of /var/cache/ after a yum update or yum install will save about 150MB from the image size

yum clean all
rm -f /etc/yum.repos.d/*.rpm; rm -fr /var/cache/*


Cleanup Locales:

for x in `ls /usr/share/locale | grep -v -i en | grep -v -i local`;do rm -fr /usr/share/locale/$x; done && \
for x in `ls /usr/share/i18n/locales/ | grep -v en_`; do rm -fr /usr/share/i18n/locales/$x; done && \
rm -fr /usr/share/locale/ca* /usr/share/locale/den /usr/share/locale/men /usr/share/locale/wen /usr/share/locale/zen
cd /usr/lib/locale;
localedef --list-archive | grep -v -i ^en | xargs localedef --delete-from-archive;
mv -f locale-archive locale-archive.tmpl;
build-locale-archive


Set the default Timezone to EST:

cp /etc/localtime /root/old.timezone && \
rm -f /etc/localtime && \
ln -s /usr/share/zoneinfo/America/New_York /etc/localtime


Remove Man Pages and Docs to preserve Space:

rm -fr /usr/share/doc/* /usr/share/man/* /usr/share/groff/* /usr/share/info/*;
rm -rf /usr/share/lintian/* /usr/share/linda/* /var/cache/man/*


Set the Terminal CLI Prompt:

Copy the included Terminal CLI Color Scheme file to /etc/profile.d so that the terminal color will be included in all child images

#!/bin/bash
if [ "$PS1" ]; then
    set_prompt () {
    Last_Command=$?
    Blue='\[\e[01;34m\]'
    White='\[\e[01;37m\]'
    Red='\[\e[01;31m\]'
    YellowBack='\[\e[01;43m\]'
    Green='\[\e[01;32m\]'
    Yellow='\[\e[01;33m\]'
    Black='\[\e[01;30m\]'
    Reset='\[\e[00m\]'
    FancyX=':('
    Checkmark=':)'

    # If it was successful, print a green check mark. Otherwise, print a red X.
    if [[ $Last_Command == 0 ]]; then
        PS1="$Green$Checkmark "
    else
        PS1="$Red$FancyX "
    fi
    # If root, just print the host in red. Otherwise, print the current user and host in green.
    if [[ $EUID == 0 ]]; then
        PS1+="$Black $YellowBack $TERMTAG $Reset $Red \\u@\\h"
    else
        PS1+="$Black $YellowBack $TERMTAG $Reset $Green \\u@\\h"
    fi
    # Print the working directory and prompt marker in blue, and reset the text color to the default.
    PS1+="$Blue\\w \\\$$Reset "
    }

    PROMPT_COMMAND='set_prompt'
fi


Prevent the .bashrc from being executed via SSH or SCP sessions:

echo -e "\nif [[ -n \"\$SSH_CLIENT\" || -n \"\$SSH_TTY\" ]]; then\n\treturn;\nfi\n" >> /root/.bashrc && \
echo -e "\nif [[ -n \"\$SSH_CLIENT\" || -n \"\$SSH_TTY\" ]]; then\n\treturn;\nfi\n" >> /etc/skel/.bashrc


Set Dockerfile Runtime command:

Default command to run when lauched via docker run

CMD /bin/bash


Dockerfile:


###########################################################
# Dockerfile to build the CentOS 6.9 Base Container
# Based on: library/centos:6.9
# DATE: 11/25/16
# COPYRIGHT: Appcontainers.com
###########################################################

# Set the base image in namespace/repo format. 
# To use repos that are not on the docker hub use the example.com/namespace/repo format.
FROM library/centos:6.9

# File Author / Maintainer
MAINTAINER Rich Nason rnason@appcontainers.com

###########################################################
#*********************  APP VERSIONS  *********************
###########################################################


###########################################################
#***********  OVERRIDE ENABLED ENV VARIABLES  *************
###########################################################

ENV TERMTAG CentOS6Base

###########################################################
#**************  ADD REQUIRED APP FILES  ******************
###########################################################

# Import keys and fix passwd issue.
RUN rpm --import /etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6

###########################################################
#***************  UPDATES & PRE-REQS  *********************
###########################################################

# Clean, Update, and Install... then clear non English local data.
RUN yum clean all && \

# Install required packages
yum -y install epel-release && \
rpm --import http://download.fedoraproject.org/pub/epel/RPM-GPG-KEY-EPEL-6 && \

# Download and install the Remi repository
cd /etc/yum.repos.d/ && \
curl -O http://rpms.famillecollet.com/enterprise/remi-release-6.rpm && \
rpm -Uvh remi-release-6*.rpm && \
rpm --import /etc/pki/rpm-gpg/RPM-GPG-KEY-remi && \
rm -fr *.rpm && \

#Enable the remi repo
sed -ie '/\[remi\]/,/^\[/s/enabled=0/enabled=1/' /etc/yum.repos.d/remi.repo && \
# sed -ie '/\[remi-php55\]/,/^\[/s/enabled=0/enabled=1/' /etc/yum.repos.d/remi.repo && \
sed -ie '/\[remi-php71\]/,/^\[/s/enabled=0/enabled=1/' /etc/yum.repos.d/remi-php71.repo && \

# Now that epel is installed, clean all again and update
yum clean all && \
yum -y update && \
# yum -y install ansible && \

# Remove yum cache this bad boy can be 150MBish
yum clean all && \
rm -fr /var/cache/*

###########################################################
#***************  APPLICATION INSTALL  ********************
###########################################################

# Install pip and configure ansible
# RUN curl "https://bootstrap.pypa.io/get-pip.py" -o "/tmp/get-pip.py" && \
# python /tmp/get-pip.py && \
# pip install pip --upgrade && \
# rm -fr /tmp/get-pip.py && \
# mkdir -p /etc/ansible/roles || exit 0 && \
# echo localhost ansible_connection=local > /etc/ansible/hosts

###########################################################
#**************  POST DEPLOY CLEAN UP  ********************
###########################################################

# Remove locales other than english
RUN for x in `ls /usr/share/locale | grep -v -i en | grep -v -i local`;do rm -fr /usr/share/locale/$x; done && \
for x in `ls /usr/share/i18n/locales/ | grep -v en_`; do rm -fr /usr/share/i18n/locales/$x; done && \
rm -fr /usr/share/locale/ca* /usr/share/locale/den /usr/share/locale/men /usr/share/locale/wen /usr/share/locale/zen && \
cd /usr/lib/locale && \
localedef --list-archive | grep -v -i ^en | xargs localedef --delete-from-archive && \
mv -f locale-archive locale-archive.tmpl && \
build-locale-archive

# Set the default Timezone to EST
RUN cp /etc/localtime /root/old.timezone && \
rm -f /etc/localtime && \
ln -s /usr/share/zoneinfo/America/New_York /etc/localtime

# Remove documentation to cut down the image size
RUN rm -fr /usr/share/doc/* /usr/share/man/* /usr/share/groff/* /usr/share/info/* && \
rm -rf /usr/share/lintian/* /usr/share/linda/* /var/cache/man/*

# Rebuild the RPM Database
RUN rm -f /var/lib/rpm/__db* && \
rpm --rebuilddb

###########################################################
#*************  CONFIGURE START ITEMS  ********************
###########################################################

ADD termcolor.sh /etc/profile.d/PS1.sh
RUN chmod +x /etc/profile.d/PS1.sh

# Add the following to prevent any additions to the .bashrc from being executed via SSH or SCP sessions
RUN echo -e "\nif [[ -n \"\$SSH_CLIENT\" || -n \"\$SSH_TTY\" ]]; then\n\treturn;\nfi\n" >> /root/.bashrc && \
echo -e "\nif [[ -n \"\$SSH_CLIENT\" || -n \"\$SSH_TTY\" ]]; then\n\treturn;\nfi\n" >> /etc/skel/.bashrc

CMD /bin/bash

###########################################################
#************  EXPOSE APPLICATION PORTS  ******************
###########################################################


###########################################################
#***************  OPTIONAL / LEGACY  **********************
###########################################################


Building the image from the Dockerfile:


docker build -t build/centos .


Packaging the final image:


Because we want to make this image as light weight as possible in terms of size, the image is flattened in order to remove the docker build tree, removing any intermediary build containers from the image. In order to remove the reversion history, the image needs to be ran, and then exported/imported. Note that just saving the image will not remove the revision history, In order to remove the revision history, the running container must be exported and then re-imported.


Run the container build:

docker run -it -d \
--name centos \
build/centos \
/bin/bash

The run statement should start a detached container, however if you are attached, detach from the container

CTL P + CTL Q


Export and Re-import the Container:

Note that because we started the build container with the name of centos, we will use that in the export statement instead of the container ID.

docker export centos | docker import - appcontainers/centos:latest


Verify:

Issuing a docker images should now show a newly saved appcontainers/centos image, which can be pushed to the docker hub.


Run the container:


docker run -it -d appcontainers/centos:latest


Dockerfile Change-log:


05/19/2017 - Update to 6.9, PHP 7.1
03/25/2017 - Created separate build/tags for raw base and base with ansible installed
11/28/2016 - Update to OS, add vim, and ansible as it will replace runconfig scripts
06/11/2016 - Update to 6.8
12/14/2015 - Update to 6.7 official, epel change.
09/29/2015 - Add Line to .bashrc to prevent additions to the basrc to be run from SSH/SCP login
08/07/2015 - Upgrade to CentOS 6.7
07/07/2015 - Squueze more space.. reduced from 270MB to 137MB
05/06/2015 - Updated configuration scripts, pre import GPG repo keys
04/27/2015 - Removed Locales other than English to conserve over 100MB
04/06/2015 - Changed Postgres Repo from postgresql9.3 postgresql-9.4