- **Fast Feedback** - Rather than having to commit/push every time you want to test out the changes you are making to your `.github/workflows/` files (or for any changes to embedded GitHub actions), you can use `act` to run the actions locally. The [environment variables](https://help.github.com/en/actions/configuring-and-managing-workflows/using-environment-variables#default-environment-variables) and [filesystem](https://help.github.com/en/actions/reference/virtual-environments-for-github-hosted-runners#filesystems-on-github-hosted-runners) are all configured to match what GitHub provides.
- **Local Task Runner** - I love [make](<https://en.wikipedia.org/wiki/Make_(software)>). However, I also hate repeating myself. With `act`, you can use the GitHub Actions defined in your `.github/workflows/` to replace your `Makefile`!
When you run `act` it reads in your GitHub Actions from `.github/workflows/` and determines the set of actions that need to be run. It uses the Docker API to either pull or build the necessary images, as defined in your workflow files and finally determines the execution path based on the dependencies that were defined. Once it has the execution path, it then uses the Docker API to run containers for each action based on the images prepared earlier. The [environment variables](https://help.github.com/en/actions/configuring-and-managing-workflows/using-environment-variables#default-environment-variables) and [filesystem](https://help.github.com/en/actions/reference/virtual-environments-for-github-hosted-runners#filesystems-on-github-hosted-runners) are all configured to match what GitHub provides.
If you are using macOS, please be sure to follow the steps outlined in [Docker Docs for how to install Docker Desktop for Mac](https://docs.docker.com/docker-for-mac/install/).
If you are using Windows, please follow steps for [installing Docker Desktop on Windows](https://docs.docker.com/docker-for-windows/install/).
If you are using Linux, you will need to [install Docker Engine](https://docs.docker.com/engine/install/).
`act` is currently not supported with `podman` or other container backends (it might work, but it's not guaranteed). Please see [#303](https://github.com/nektos/act/issues/303) for updates.
When running `act` for the first time, it will ask you to choose image to be used as default.
It will save that information to `~/.actrc`, please refer to [Configuration](#configuration) for more information about `.actrc` and to [Runners](#runners) for information about used/available Docker images.
--container-architecture string Architecture which should be used to run containers, e.g.: linux/amd64. If not specified, will use host default architecture. Requires Docker server API Version 1.41+. Ignored on earlier Docker server platforms.
A `MODULE_NOT_FOUND` during `docker cp` command [#228](https://github.com/nektos/act/issues/228) can happen if you are relying on local changes that have not been pushed. This can get triggered if the action is using a path, like:
```yaml
- name: test action locally
uses: ./
```
In this case, you _must_ use `actions/checkout@v2` with a path that _has the same name as your repository_. If your repository is called _my-action_, then your checkout step would look like:
GitHub Actions offers managed [virtual environments](https://help.github.com/en/actions/reference/virtual-environments-for-github-hosted-runners) for running workflows. In order for `act` to run your workflows locally, it must run a container for the runner defined in your workflow file. Here are the images that `act` uses for each runner type and size:
Additionally, some software might still not work even if installed properly, since GitHub Actions are running in fully virtualized machines while `act` is using Docker containers (e.g. Docker does not support running `systemd`).
In case of any problems [please create issue](https://github.com/nektos/act/issues/new/choose) in respective repository (issues with `act` in this repository, issues with `nektos/act-environments-ubuntu:18.04` in [`nektos/act-environments`](https://github.com/nektos/act-environments) and issues with any image from user `catthehacker` in [`catthehacker/docker_images`](https://github.com/catthehacker/docker_images))
If you need an environment that works just like the corresponding GitHub runner then consider using an image provided by [nektos/act-environments](https://github.com/nektos/act-environments):
- [`nektos/act-environments-ubuntu:18.04`](https://hub.docker.com/r/nektos/act-environments-ubuntu/tags) - built from the Packer file GitHub uses in [actions/virtual-environments](https://github.com/actions/runner).
- [`catthehacker/ubuntu:full-20.04`](https://hub.docker.com/r/catthehacker/ubuntu/tags) - built from Dockerfile based on the Packer template from [actions/virtual-environments](https://github.com/actions/runner).
This image size is about `61GB` unpacked (`23GB` compressed) but contains more recent software versions (as of date of build).
To run `act` with secrets, you can enter them interactively, supply them as environment variables or load them from a file. The following options are available for providing secrets:
-`act -s MY_SECRET=somevalue` - use `somevalue` as the value for `MY_SECRET`.
-`act -s MY_SECRET` - check for an environment variable named `MY_SECRET` and use it if it exists. If the environment variable is not defined, prompt the user for a value.
You can provide default configuration flags to `act` by either creating a `./.actrc` or a `~/.actrc` file. Any flags in the files will be applied before any flags provided directly on the command line. For example, a file like below will always use the `nektos/act-environments-ubuntu:18.04` image for the `ubuntu-latest` runner:
Additionally, act supports loading environment variables from an `.env` file. The default is to look in the working directory for the file but can be overridden by:
Every [GitHub event](https://developer.github.com/v3/activity/events/types) is accompanied by a payload. You can provide these events in JSON format with the `--eventpath` to simulate specific GitHub events kicking off an action. For example:
Act supports using and authenticating against private GitHub Enterprise servers.
To use your custom GHE server, set the CLI flag `--github-instance` to your hostname (e.g. `github.company.com`).
Please note that if your GHE server requires authentication, we will use the secret provided via `GITHUB_TOKEN`.
Please also see the [official documentation for GitHub actions on GHE](https://docs.github.com/en/enterprise-server@3.0/admin/github-actions/about-using-actions-in-your-enterprise) for more information on how to use actions.
