Is there a list of used ports?

Hey there :wave:

I am currently experimenting with GitHub Actions, and although my first impression is pretty good, a question came up: In my tests I am building a number of Docker containers (this is actually part of the test), and after that I start them using docker run.

Basically, this works (at least on Ubuntu), but some of the ports I would like to use are already being used.

So, my question is: Is there a list of already used ports available somewhere?

Have a nice day,


You can add one step to run docker ps –a command to list all containers and in your workflow. And then run docker port CONTAINER to show all mapped ports.

Please refer to this docker port document:

What’s the exact error message you got?  

For us to understand your scenario more clearly, could you please share your workflow yml content and workflow run logs here? If you use a public repo, could you provide your workflow link? 

Hi Yanjingzhu!

Thanks for your answer!

The repository is actually public, and you can find it (including the GitHub actions branch) here:

The concrete error message is:

Error starting userland proxy: listen tcp bind: address already in use.

The appropriate build is this one:

Thanks for the hint with docker ps, but I was hoping for an official list (maybe not all currently free ports are available in the long run), but it’s a way to go…

Looking forward to your feedback and ideas :slight_smile:

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Thank you for your workfkow yml and logs. 3306 port is the default port which used by MySQL. MySQL is installed on Github actions Ubuntu runner.  

So before set-up a MySQL which host port is 3306 in Docker, please make sure the Default MySQL has been shutted-down.

Please add a step before Run roboter to shutdown the Default MySQL:

    - name: Shutdown Ubuntu MySQL (SUDO)
      run: sudo service mysql stop # Shutdown the Default MySQL, "sudo" is necessary, please not remove it

For more information, please refer to

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Thanks a lot :slight_smile: