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Docker Entrypoint vs Kubernetes Command

Fleeting

Notes This table summarizes the field names used by Docker and Kubernetes.

Description Docker field name Kubernetes field name
The command run by the container Entrypoint command
The arguments passed to the command Cmd args

When you override the default Entrypoint and Cmd, these rules apply:

  • If you do not supply command or args for a Container, the defaults defined in the Docker image are used.
  • If you supply a command but no args for a Container, only the supplied command is used. The default EntryPoint and the default Cmd defined in the Docker image are ignored.
  • If you supply only args for a Container, the default Entrypoint defined in the Docker image is run with the args that you supplied.
  • If you supply a command and args, the default Entrypoint and the default Cmd defined in the Docker image are ignored. Your command is run with your args.

Here are some examples:

Image Entrypoint Image Cmd Container command Container args Command run
[/ep-1] [foo bar] <not set> <not set> [ep-1 foo bar]
[/ep-1] [foo bar] [/ep-2] <not set> [ep-2]
[/ep-1] [foo bar] <not set> [zoo boo] [ep-1 zoo boo]
[/ep-1] [foo bar] [/ep-2] [zoo boo] [ep-2 zoo boo]

— https://kubernetes.io/docs/tasks/inject-data-application/define-command-argument-container/#notes

In short, when you define an entrypoint in docker, kubernetes may well override it.