Table of Contents

Docker auf RHEL / CentOS 7/8

In this 3-article series, we will discuss about Docker, is an open-source lightweight virtualization tool which runs at top of Operating System level, allowing users to create, run and deploy applications, encapsulated into small containers.

Installation von Docker und Docker-Compose

Step 1 - Install deps, add docker Repo and setup Docker: 

# yum install -y yum-utils device-mapper-persistent-data lvm2
# yum-config-manager --add-repo https://download.docker.com/linux/centos/docker-ce.repo
# yum update

# yum install docker-ce docker-ce-cli --nobest -y

# systemctl enable docker --now

Step 2 - Install docker-compose binary: 

# newest_version="$(curl -s https://api.github.com/repos/docker/compose/releases/latest | grep -Po '"tag_name": "\K.*?(?=")')"

# curl -L "https://github.com/docker/compose/releases/download/${newest_version}/docker-compose-$(uname -s)-$(uname -m)" -o /bin/docker-compose
# chmod +x /bin/docker-compose

# curl -L https://raw.githubusercontent.com/docker/compose/$(docker-compose version --short)/contrib/completion/bash/docker-compose -o /etc/bash_completion.d/docker-compose

# docker-compose version

Installation Docker Environment

Step 1 - Create Project Folder: 

# mkdir /opt/docker-PROJECT

Step 2 - Create Project Docker Compose-File: 

# vim /opt/docker-PROJECT/docker_compose.yml

DEMO - Docker Compose File: 

version: "3.2"

services:
  # ----------------------------------------------------------------------------
  pihole:
    image: IMAGE/IMAGE:latest
    container_name: "PROJECT-main"
    volumes:
      - /opt/docker-PROJECT/DOCKERHOST/:/etc/CONTAINER/
      - /etc/localtime:/etc/localtime:ro
    environment:
      - VARIABLE1=value_xy
      - VARIABLE2=value_xy
    #ports:
    #  - 53:53/tcp
    #  - 53:53/udp
    #  - 67:67/udp
    #  - 81:80
    #networks:
    #  - local
    
    restart: always
    network_mode: "host"

# ------------------------------------------------------------------------------
#networks:
#  local:
#    driver: bridge

Step 3 - Start / Stop Docker Compose Projects: 

# docker-compose -f /opt/docker-PROJECT/docker_compose.yml up -d
# docker-compose -f /opt/docker-PROJECT/docker_compose.yml down

Enabling access to files protected by SELinux In order to give a container access to files protected by SELinux, you need to use one of the following volume options: z or Z.

  • z(lower): relabels the content you’re mounting into the container, and makes it shareable between containers.
  • Z(upper): relabels the content you’re mounting into the container, and makes it private. So, mounting this file in another container won’t work.

http://jaormx.github.io/2018/selinux-and-docker-notes/

FIXME

Docker Grundlagen

This type of Linux containers are proven to be fast, portable and secure. The processes that run in a Docker container are always isolated from the main host, preventing outside tampering.

https://www.linuxtechi.com/install-use-docker-compose-to-deploy-containers-in-centos7/

This tutorial provides a starting point on how to install Docker, create and run Docker containers on CentOS/RHEL 7/6, but barley scratches the surface of Docker.

https://www.tecmint.com/install-docker-and-learn-containers-in-centos-rhel-7-6/