SteamCMD is a command-line version of the Steam Client. Its primary use is to install and update various dedicated servers available on Steam. This container was made to be used as a base image for building out other game specific containers but can be used for any other tasks SteamCMD can perform. An example of a container image built on top of this one is PalWorld.
For more detailed information about using SteamCMD see the official wiki.
docker pull bubylou/steamcmd:latest
docker run -it bubylou/steamcmd:latest +login anonymous +app_update 4020 +quit