Prerequisites

A virtual machine running CentOS 7 is required for this setup.

Installing Docker 17.09.0-ce

1. Remove Existing Docker Components

   • Uninstall any previously installed Docker packages:

     yum remove docker\*
     

   • Remove the container-selinux package to avoid conflicts:

     yum remove container-selinux-1.12.5-14.el7.centos.x86_64
     

2. Set Up Docker Repository

   • Install yum-utils for repository management:

     sudo yum install -y yum-utils
     

   • Add the official Docker CE repository:

     sudo yum-config-manager --add-repo https://download.docker.com/linux/centos/docker-ce.repo
     

   • Update the package cache:

     sudo yum makecache fast
     

3. Install Docker CE

   • List availible Docker CE versions:

     yum list docker-ce.x86_64 --showduplicates | sort -r
     

   • Enstall Docker CE version 17.09.0:

     sudo yum -y install docker-ce-17.09.0.ce
     

4. Start Docker and Verify Installation

   • Start the Docker service:

     systemctl start docker
     

   • Enable Docker to start on boot:

     systemctl enable docker
     

   • Check the Docker version and info:

     docker info
     

Configuring Docker Startup Parameters

Examine the Docker service file to understand its configuration:

cat /lib/systemd/system/docker.service

The key paramter for customization is ExecStart in the [Service] section. This defines the command executed when starting Docker.

To modify the network address and other settings, update the ExecStart line. Below is an example configuration with custom parameters:

ExecStart=/usr/bin/dockerd --bip=172.18.0.1/16 -H tcp://0.0.0.0:5257 -H unix:///var/run/docker.sock --pidfile=/var/run/docker.pid

Parameter Explanation:

• --bip=172.18.0.1/16: Sets the bridge IP address for container networking.
• -H tcp://0.0.0.0:5257: Configures Docker to listen on TCP port 5257 for remote connections.
• -H unix:///var/run/docker.sock: Specifies the Unix socket for local Docker communication.
• --pidfile=/var/run/docker.pid: Defines the location for the Docker daemon's PID file.

For a full list of available options, run:

dockerd --help

Applying Configuration Changes

1. Stop the Docker service:

   systemctl stop docker
   

2. Reload the systemd configuration to apply changes:

   systemctl daemon-reload
   

3. Start Docker with the new settings:

   systemctl start docker