Asked by: Lorelay Egle
asked in category: General Last Updated: 20th May, 2020

Can we have multiple CMD in Dockerfile?

There can only be one CMD instruction in a Dockerfile. If you list more than one CMD then only the last CMD will take effect. If CMD is used to provide default arguments for the ENTRYPOINT instruction, both the CMD and ENTRYPOINT instructions should be specified with the JSON array format.

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Just so, can I have multiple CMD in Dockerfile?

At all times, there can be only one CMD. You are right, the second Dockerfile will overwrite the CMD command of the first one. Docker will always run a single command, not more. So at the end of your Dockerfile, you can specify one command to run.

Subsequently, question is, can a docker container run multiple applications? It's ok to have multiple processes, but to get the most benefit out of Docker, avoid one container being responsible for multiple aspects of your overall application. You can connect multiple containers using user-defined networks and shared volumes. Then you start supervisord , which manages your processes for you.

Consequently, can we have multiple entrypoint in Dockerfile?

But since Docker allows only a single ENTRYPOINT (to be precise, only the last ENTRYPOINT in the Dockerfile has an effect), you need to find a way to run multiple processes (the tunnel and the application) with a single command. Let's see how you can do it.

What is CMD in Dockerfile?

CMD is the default command to be run by the entrypoint. It sets default command and/or parameters, however, we can overwrite those commands or pass in and bypass the default parameters from the command line when docker runs. ENTRYPOINT is the program to run the given command.

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