When you are using the docker image, you can specify the configuration file by using the `CONFIG_FILE` environment variable. Make sure that the file is mounted into the container as a volume:
You may notice the commands above are both incomplete, because it is not the time to run the act runner yet.
Before running the act runner, we need to register it to your Gitea instance first.
## Registration
Registration is required before running the act runner, because the runner needs to know where to get jobs from.
And it is also important to Gitea instance to identify the runner.
### Runner levels
You can register a runner in different levels, it can be:
- Instance level: The runner will run jobs for all repositories in the instance.
- Organization level: The runner will run jobs for all repositories in the organization.
- Repository level: The runner will run jobs for the repository it belongs to.
Note that the repository may still use instance-level or organization-level runners even if it has its own repository-level runners. A future release may provide an option to allow more control over this.
### Obtain a registration token
The level of the runner determines where to obtain the registration token.
A registration token can also be obtained from the gitea [command-line interface](../../administration/command-line.en-us.md#actions-generate-runner-token):
When you have registered the runner, you can find a new file named `.runner` in the current directory.
This file stores the registration information.
Please do not edit it manually.
If this file is missing or corrupted, you can simply remove it and register again.
If you want to store the registration information in another place, you can specify it in the configuration file,
and don't forget to specify the `--config` option.
### Register the runner with docker
If you are using the docker image, behaviour will be slightly different. Registration and running are combined into one step in this case, so you need to specify the registration information when running the act runner.
The labels of a runner are used to determine which jobs the runner can run, and how to run them.
The default labels are `ubuntu-latest:docker://node:16-bullseye,ubuntu-22.04:docker://node:16-bullseye,ubuntu-20.04:docker://node:16-bullseye,ubuntu-18.04:docker://node:16-buster`.
It is a comma-separated list, and each item is a label.
Let's take `ubuntu-22.04:docker://node:16-bullseye` as an example.
It means that the runner can run jobs with `runs-on: ubuntu-22.04`, and the job will be run in a docker container with the image `node:16-bullseye`.
If the default image is insufficient for your needs, and you have enough disk space to use a better and bigger one, you can change it to `ubuntu-22.04:docker://<the image you like>`.
You can find more useful images on [act images](https://github.com/nektos/act/blob/master/IMAGES.md).
If you want to run jobs in the host directly, you can change it to `ubuntu-22.04:host` or just `ubuntu-22.04`, the `:host` is optional.
However, we suggest you to use a special name like `linux_amd64:host` or `windows:host` to avoid misusing it.
Starting with Gitea 1.21, you can change labels by modifying `container.labels` in the runner configuration file (if you don't have a configuration file, please refer to [configuration tutorials](#configuration)).
The runner will use these new labels as soon as you restart it, i.e., by calling `./act_runner daemon --config config.yaml`.