In this preview of Containers for Developers and Quality Assurance (LFS254) training course from The Linux Foundation, we’ve covered Docker installation, introduced Docker Machine, performed basic Docker container and image operations, and looked at Dockerfiles and Docker Volumes.
This final article in the series looks at Docker Compose, which is a tool you can use to create multi-container applications with just one command. If you are using Docker for Mac or Windows, or you install the Docker Toolbox, then Docker Compose will be available by default. If not, you can download it manually.
To try out WordPress, for example, let’s create a folder called wordpress, and, in that folder, create a file called docker-compose.yaml. We will be exporting the wordpress container on the 8000 port of the host system.
When we start an application with Docker Compose, it creates a user-defined network on which it attaches the containers for the application. The containers communicate over that network. As we have configured Docker Machine to connect to our dockerhost, Docker Compose would also use that.
Now, with the docker-compose up command, we can deploy the application. With docker-compose ps command, we can list the containers created by Docker Compose, and with docker-compose down, we can stop and remove the containers. This also removes the network associated with the application. To additionally delete the associated volume, we need to pass the -voption with the docker-compose down command.
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This online course is presented almost entirely on video, and the material is prepared and presented by Neependra Khare (@neependra), Founder and Principal Consultant at CloudYuga, Docker Captain, and author of the Docker Cookbook.