Create a GitLab Runner process wrapper

What does this MR do?

Implements a wrapper for the GitLab Runner process.

Why was this MR needed?

Justification for the wrapper can be found in Create a GitLab Runner process wrapper (#38216 - closed) • Tomasz Maczukin • 17.6

What's the best way to test this MR?

After building/downloading the binary, you can start runner through the wrapper and interact with the gRPC server.

If normally you start runner with:

gitlab-runner run --config ~/.gitlab-runner/config.toml

then to use the wrapper you should start it as:

gitlab-runner wrapper -- run --config ~/.gitlab-runner/config.toml

The wrapper will explicitly call the Runner binary with all arguments that are present after --. In other words, everything after -- will be taken as arguments and called with gitlab-runner through exec.Command.

The syntax is:

gitlab-runner [global-options] wrapper [command-options] -- [internal-global-options] [internal-command] [internal-command-options]

Where:

• global-options are the regular global options available for gitlab-runner binary and that will be used by the wrapper process only.

• command-options are options for the wrapper command. Currently Wrapper provides two of these:

  • --grpc-listen which defines listen address for the gRPC server. Default is localhost:7777.
  • --process-termination-timeout which defines what's the timeout of waiting for the internal runner process termination when the wrapper process is terminated. Default is 10s.

• internal-global-options are the gitlab-runner global options that will be used by the internal process only.

• internal-command is any of the gitlab-runner commands

• internal-comand-options is any of the chosen command options

Runner wrapper will take the arguments after -- and transition it to:

gitlab-runner [internal-global-options] [internal-command] [internal-command-options]

and this will be started in a dedicated process group, managed by the wrapper.

Some examples:

If you want to customize the gRPC server listening address:

gitlab-runner wrapper --grpc-listen ":1111" -- run --config ~/.gitlab-runner/config.toml

You can get some more logs from the wrapper by enabling debug logging for the wrapper process:

gitlab-runner --debug wrapper -- run --config ~/.gitlab-runner/config.toml

If you want to enable (for any reason) debug logging for the internally started runner process, the global --debug flag must be added after --:

gitlab-runner wrapper -- --debug run --config ~/.gitlab-runner/config.toml

or to have both the wrapper and the internal process logging in debug:

gitlab-runner --debug wrapper -- --debug run --config ~/.gitlab-runner/config.toml

Remember that none of the options used in context of the wrapper command will be used by the internal process, as they don't share the memory. Wrapper will start totally separate process (just tracked and "owned" by it) and any configuration needs to be explicitly provided after --.

What are the relevant issue numbers?

Closes #38216 (closed)