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dockerrabbitmqdocker-run

Why can we have more time -p options in docker run command line

I have seen a docker run command line as following:

docker run -it --rm --name rabbitmq -p 5672:5672 -p 15672:15672 rabbitmq:3-management

This command launch the image rabbitmq:3-management With the option --it, it runs in the interactive mode, so we can execute commands inside the container while it is still running. With the option --name, it allow me to assign the rabbitmq name to my container.

What i dont understand is the -p option, why it is twice ?

I know that the only way to access the process is from inside of it. To allow external connections to the container, you have to open (publish) specific ports.

So it is working like: docker run -p 8080:80 [image_name]. so it this command i to map TCP port 80 in the container to port 8080 on the Docker host.

So my question is why it is like this

-p 5672:5672 -p 15672:15672 rabbitmq:3-management

Why i have -p twice ? Why i have the same port 5672:5672 and 15672:15672 ?

Thanks

Solution

  • RabbitMQ accepts TCP client connections (consumers, publishers) on port 5672 by default. So -p 5672:5672 means "map port 5672 on the host to port 5672 of this container".

    The RabbitMQ Management UI is an HTTP server which listens on port 15672 by default. So -p 15672:15672 means "map port 15672 on the host to port 15672 of this container" so that you can access the management UI in a web browser like localhost:15672.

    In both cases, the number on the left is the host port number. If 5672 was a port you were already using on your host, you could map a different port on your host to the container like -p 95672:5672.