References/Resources

• Docker Toolbox Overview
• Docker Getting Started Tutorial
• Docker Hub
• Dockerfile Reference
• Dockerize PostgreSQL
• Docker Self-Paced Online Training
• Docker ARG, ENV, and .env
• Setting Default Docker Environment Variables During Image Build
• Docker Tutorial Series
• How to use Entrypoint

Verify Installation

This command:

• creates and runs a Docker container
• in the container, the hello-world image is loaded

$ docker run hello-world

An image is a filesystem and parameters to use at runtime.

A container is a running instance of an image.

List All Containers

$ docker ps -a

List All Images

$ docker images

Run a Container, with Arguments

$ docker run docker/whalesay cowsay boo

Dockerfile

FROM ubuntu:14.04

# install cowsay, and move the "default.cow" out of the way so we can overwrite it with "docker.cow"
RUN apt-get update && \
    apt-get install -y cowsay --no-install-recommends && \
    rm -rf /var/lib/apt/lists/* && \
    mv /usr/share/cowsay/cows/default.cow /usr/share/cowsay/cows/orig-default.cow

# "cowsay" installs to /usr/games
ENV PATH $PATH:/usr/games

COPY docker.cow /usr/share/cowsay/cows/
RUN ln -sv /usr/share/cowsay/cows/docker.cow /usr/share/cowsay/cows/default.cow

CMD ["cowsay"]

Common Commands

List running containers.

$ docker ps

View details of an image.

$ docker inspect image-name

Check if a specific container is running.

$ docker inspect --format "\{\{.State.Running\}\}" container-name

link

View Logs

$ docker logs container-name
$ docker logs -f container-name

View ports

$ docker port container-name

Connect to running container

$ docker exec -it [container-id] bash

Restart container

$ docker restart container-name

Stop all running containers

$ docker stop $(docker ps -a -q)

Remove all containers

$ docker rm $(docker ps -a -q)

Build an Image

Run the following command from a folder where a Dockerfile exists.

$ docker build -t username/image .

Dockerfile

Dockefile Examples

FROM <image>
LABEL version="1.0"
LABEL description="Description of this image."
LABEL maintainer "Richard Davis <radavis@example.com>"
WORKDIR /path/to/workdir
USER <username>
ENV <key> <value>
ADD <source> <destination>
COPY <source> <destination>
RUN <command>
EXPOSE <port>
VOLUME ["/data"]
CMD ["executable", "param1", "param2"]
ENTRYPOINT ["executable", "param1", "param2"]
ONBUILD [INSTRUCTION]
ARG <name>[=<default value>]

The LABEL instruction adds metadata to an image.

The WORKDIR instruction sets the working directory for any RUN, CMD, ENTRYPOINT, COPY and ADD instructions that follow it in the Dockerfile.

The ADD instruction copies new files, directories or remote file URLs from <src> and adds them to the filesystem of the image at the path <dest>.

The COPY instruction copies new files or directories from <src> and adds them to the filesystem of the container at the path <dest>.

The RUN instruction will execute any commands in a new layer on top of the current image and commit the results.

The VOLUME instruction creates a mount point with the specified name and marks it as holding externally mounted volumes from native host or other containers.

The main purpose of a CMD is to provide defaults for an executing container.

An ENTRYPOINT allows you to configure a container that will run as an executable.

The ONBUILD instruction adds to the image a trigger instruction to be executed at a later time, when the image is used as the base for another build. The trigger will be executed in the context of the downstream build, as if it had been inserted immediately after the FROM instruction in the downstream Dockerfile.

The ARG instruction defines a variable that users can pass at build-time to the builder with the docker build command using the --build-arg <varname>=<value> flag.