How can I setup Docker on a CentOS 7? How to install and use Docker CE on a CentOS Linux 7 server? Docker is free and open-source software. It automates the deployment of any application as a lightweight, portable, self-sufficient container that will run virtually anywhere. Typically you develop software on your laptop/desktop.
I’m just getting started with Docker. I’ve thought for years that containerization is a great idea, but I haven’t actually done anything with containers yet. Time to get started.
- The official build of CentOS.
- Install Docker Compose on CentOS 8 CentOS 8. We have Docker installed and running, let’s now change gear to Docker Compose. Docker Compose is a tool used to define and run multi-container Docker applications. The application services are configured using a Compose file.
I ran through a couple tutorials on the Docker docs site and created a cloud.docker.com account to get some basic familiarity.
I found the CentOS container repository on Docker Hub: https://hub.docker.com/_/centos/
Let’s try running it!
$ docker pull centos
$ docker run centos
Did it do anything? It looks like it did something. At least, it didn’t give me an error. What did it do? How do I access it?
$ docker container ls
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
Nothing is actively running. That makes sense, because we’re not telling the containerized OS to do anything — it starts, it doesn’t have anything to do, and so it shuts down immediately. Instead we can tell it to run interactively and with a terminal by specifying a couple options:
-i, --interactive (“allocate a pseudo-TTY”, i.e. a terminal)
-t, --tty
(see docker run --help for details)
$ docker run -i -t centos
[root@4f0b435cdbd7 /]#
I’m in!
What if I want to modify the container? Right now it is pretty bare-bones. For example, this doesn’t even have man installed:
[root@4f0b435cdbd7 /]# man man
bash: man: command not found
[root@4f0b435cdbd7 /]# yum install man
...
[root@4f0b435cdbd7 /]# man man
No manual entry for man
Quite the improvement! Now we need to save our change:
[root@4f0b435cdbd7 /]# exit
$ docker commit 4f0b435cdbd7 man-centos
$ docker run -i -t man-centos
[root@953c512d6707 /]# man man
No manual entry for man
Progress! Now we have a CentOS container where man is already installed. Exciting.
Docker Run Centos Bash
I can’t (that I know of) inspect the container and know whether or not man is installed without running it. That’s fine for many cases, but next I will attempt to figure out how specify via a Dockerfile that man is installed.