Docker beginner.
I was able to launch a virtual environment using Docker docker-compose on Mac,
What is this OS?
Also, I dropped the image of "Ruby" from Dockerhub,
In other words, it means that you have dropped the Linux environment that contains Ruby from the beginning.
For example, isn't it possible to drop a linux environment with CentOS + Ruby?
Since there was an image of CentOS on Dockerhub, I do not know what to do.
Or you may not understand the concept of "Docker image".
If i am familiar with this area, please teach me.

  • Answer # 1


    For example, isn't it possible to drop a linux environment with CentOS + Ruby?

    If you find such a thing, you can.
    I haven't looked for it, so I don't know if it's there, but I think it is.

  • Answer # 2


    What is this OS?

    The container is basically a container that runs some process, and the OS part (kernel) is shared with the Docker host.

    centos Docker image is containerized systemd, which is the first boot process. The configuration file read by systemd and the child process to be executed are the same as Centos, so in a broad sense it can be called the Linux environment, but as mentioned above, the OS kernel part is the Docker host Is used.

    It is possible to create an environment with Ruby based on the Centos Docker image, so you can drop it if it is publicly available. (I don't know if such an image really exists.)

    But basically I think it's better to use an image that contains only what you need, or to make it yourself, rather than using a large image in vain.

  • Answer # 3

    If you want to install CentOS instead of Docker, download the CentOS installation image, create a new machine in VirtualBox, and install it.
    It would be nice to add Ruby to it.