Which command would you use to update an existing container?

Which command would you use to update an existing container?

• A. docker upgrade
• B. docker update
• C. docker restart
• D. docker redeploy

Answer: (C)

To update an existing container, the correct approach involves using the `docker update` command. This command is specifically designed to modify the resource limits of an already running container. It allows you to change settings such as CPU and memory limits while the container is operational, without the need for stopping it. In the context of managing containers, the command `docker restart` is used to stop and then start a container again, which does not truly update the container in terms of its configuration or application. Instead, it merely refreshes the current instance. The choice of `docker upgrade` does not exist within the standard Docker command set, and `docker redeploy`, while it sounds plausible, does not accurately reflect a recognized command in Docker for updating an existing container. Once a container is created, if you need to change its image or configuration significantly, you would typically have to create a new container based on the updated specifications. Therefore, utilizing `docker update` is the correct command for modifying an existing container without recreating it.

To update an existing container, the correct approach involves using the docker update command. This command is specifically designed to modify the resource limits of an already running container. It allows you to change settings such as CPU and memory limits while the container is operational, without the need for stopping it.

In the context of managing containers, the command docker restart is used to stop and then start a container again, which does not truly update the container in terms of its configuration or application. Instead, it merely refreshes the current instance.

The choice of docker upgrade does not exist within the standard Docker command set, and docker redeploy, while it sounds plausible, does not accurately reflect a recognized command in Docker for updating an existing container. Once a container is created, if you need to change its image or configuration significantly, you would typically have to create a new container based on the updated specifications. Therefore, utilizing docker update is the correct command for modifying an existing container without recreating it.