Differences between docker entrypoint cmd

In dockerfile writing, entrypoint cmd can only be used once. If there are multiple entrypoint cmd commands, only the last command takes effect;

The main difference between entrypoint and CMD is that the method for passing the docker run parameter is not available;

Example:

...

CMD ["Echo"]

Run

docker run $IMAGE_ID echo carson

The command specified by CMD can beOverwriteIf the command passed by docker run is the same as the command specified by CMD, it will be overwritten;

This echo overwrites cmd ["Echo"], so the final result is: Carson

...

Entrypoint ["Echo"]

Run

docker run $IMAGE_ID echo carson

The command specified by entrypoint is only a command passed by docker run at the entry point will be passed to entrypoint, so it will not be overwritten;

Entrypoint will pass all the content after the container name as a parameter to the specified command (not overwrite the command), and this echo will be executed as a parameter, does not overwrite entrypoint ["Echo;

So the execution result is Echo Carson.

Everyone must have a question.

What is the execution sequence of the two entrypoint docker run commands?

In dockerfile, the parameter specified by entrypoint must be executed before the parameter specified by docker run;

Example:

...

Entrypoint ["Echo", "Carson"]

Run

docker run $IMAGE_ID good

It is equivalent to executing:

Echo Carson good

Run Command vs cmd command

All exist in dockerfile. Build image to execute the Run Command; execute cmd when run; CMD is the final command executed by image;

This article is from the "Siberian wolf" blog, please be sure to keep this source http://kernal.blog.51cto.com/8136890/1553182

Differences between docker entrypoint cmd