Docker in Action

Getting Started

Install Docker Engine by following instructions here.

Run the command to check that Docker Engine is working correctly.

sudo docker run hello-world

Follow the instructions here to run Docker without sudo.

Common Commands

Running a container from image, detached to background. The container will be running automatically.

To run the programs interactive, use the -it flag.

To delete container after finishing run, use the --rm flag.

docker run --detach --name webcontainer nginx:latest

However, to create a container from an image but in stopped state, use the create command.

docker create --name webcontainer nginx:latest
docker start webcontainer

To check actively running containers, run the ps command.

docker ps

Containers can be restart and verified to be restarted correctly.

docker stop webcontainer # Stops the container
docker restart webcontainer
docker logs webcontainer

To run additional programs in a docker container, use the exec command.

docker exec webcontainer ls # Runs the ls command inside webcontainer

Images

To pull an image only rather than spin containers up, use the pull command.

docker pull nginx:latest
docker pull quay.io/dockerinaction/ch3_hello_registry:latest # from alternate sources not from docker hub

To save the image as a tar file, use the save command. Then, load it using the load command.

docker save -o nginx.tar nginx:latest
docker load –i nginx.tar

A docker image can also be built using a dockerfile.

docker build -t test:latest ch3_dockerfile # ch3_dockerfile is a directory containing the Dockerfile

Images can be deleted using the rmi command.

docker rmi test:latest

Volumes

There are 2 types of volumes in Docker: Bind mounts and Docker-managed volumes.

Bind Mount volumes are useful to share data across processes.

The -v flag is used to create a mapping: key is the path on the host and value is absolute path to container location.

docker run -d --name bmweb -v ~/example-docs:/usr/local/apache2/htdocs -p 80:80 httpd:latest