K8s command vs Docker ENTRYPOINT

k8s_vs_docker_command_entrypoint.md

K8s command vs Docker ENTRYPOINT

Summary

• command in K8s is analogous to ENTRYPOINT in Docker
• args in K8s is analogous CMD in Docker

In Docker:

CMD has three forms

• CMD ["executable", "param1", "param2"] exec form, preferred form
• CMD ["param1", "param2"] defaults to ENTRYPOINT
• CMD command param1 param2 shell form

There can only be one CMD instruction in a Dockerfile.

The main purpose of CMD is to provide defaults for an executing container

Any arguments to docker run ... overrides CMD.

ENTRYPOINT has two forms

• ENTRYPOINT ["executable", "param1", "param2"] exec form, preferred form
• ENTRYPOINT command param1 param2 shell form

An ENTRYPOINT allows you to configure a container that will run as an executable

Any arguments to docker run ... get appended after all elements in an exec form ENTRYPOINT, and will override all elements specified using CMD.

You can override the ENTRPOINT instruction using the docker run --entrypoint flag.