docker.md

Docker

Table of Contents generated with DocToc

• Create an image
• Create a container
• Container attach and detach
• Clean up
  • Container
  • Volumes
  • Images
• Docker tools
  • VirtualBox behind a proxy
  • Define disk size when creating VM

Create an image

In a directory with a Dockerfile:

docker build -t <image_name>[:<image_tag>] .

Build behind a proxy :

docker build -t <image_name>[:<image_tag>] --build-arg http_proxy=<proxy_url> --build-arg https_proxy=<proxy_url> .

Create a container

Create a container from a CentOS 7 image and run a Bash shell

docker run -it centos:7 /bin/bash

Options:

• -i : interactive mode, keep STDIN open
• -t : associate a pseudo TTY

Container attach and detach

Detach from a running container : CTRL+p+q

Attach to a running container:

docker attach <container-id>

Network

Docker uses 172.17.0.0 for the docker0 interface.

When creating networks Docker increments the subnet (172.18, 172.19...). If your local network is on the 172.x.y.z subnet it will may conflict at some point in time with a docker bridge.

To solve this issue you can create a network manually like in the following example

docker network create --subnet 192.168.1.0/24

Or define the network in your docker-compose file

networks:
    default:
        driver: bridge
        ipam:
            driver: default
            config:
                - subnet: 192.168.2.0/24

Clean up

Container

Remove dangling containers

docker container prune

Volumes

docker volume prune

or

docker volume rm $(docker volume ls -f dangling=true -q)

Images

docker image prune

or

docker rmi $(docker images -q -f dangling=true)

Docker tools

Windows tip for Cygwin shell configuration, put the following code in .zshrc, .bashrc...:

eval $(docker-machine env default)
export no_proxy=$no_proxy,$(docker-machine ip default)

VirtualBox behind a proxy

Create the default VM with the following command:

docker-machine create -d virtualbox \
--engine-env HTTP_PROXY=[proxy_url] \
--engine-env HTTPS_PROXY=[proxy_url] \
--engine-env NO_PROXY=localhost \
default

Define disk size when creating VM

Example for 50GB disk (default value: 20GB)

docker-machine create -d virtualbox \
--virtualbox-disk-size 50000 \
default