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"Think globally, act locally"

Run your GitHub Actions locally! Why would you want to do this? Two reasons:

  • 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 and filesystem are all configured to match what GitHub provides.
  • Local Task Runner - I love make. However, I also hate repeating myself. With act, you can use the GitHub Actions defined in your .github/workflows/ to replace your Makefile!

How Does It Work?

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 and filesystem are all configured to match what GitHub provides.

Let's see it in action with a sample repo!



Necessary prerequisites for running act

act depends on docker to run workflows.

If you are using macOS, please be sure to follow the steps outlined in Docker Docs for how to install Docker Desktop for Mac.

If you are using Windows, please follow steps for installing Docker Desktop on Windows.

If you are using Linux, you will need to install Docker Engine.

act is currently not supported with podman or other container backends (it might work, but it's not guaranteed). Please see #303 for updates.

Installation through package managers

Homebrew (Linux/macOS)

homebrew version

brew install act

or if you want to install version based on latest commit, you can run below (it requires compiler to be installed installed but Homebrew will suggest you how to install it, if you don't have it):

brew install act --HEAD

MacPorts (macOS)

sudo port install act

Chocolatey (Windows)


choco install act-cli

Scoop (Windows)


scoop install act

AUR (Linux)


yay -S act

Nix (Linux/macOS)

Nix recipe

Global install:

nix-env -iA nixpkgs.act

or through nix-shell:

nix-shell -p act

Go (Linux/Windows/macOS/any other platform supported by Go)

If you have Go 1.16+, you can install latest released version of act directly from source by running:

go install[email protected]

or if you want to install latest unreleased version:

go install[email protected]

If you want a smaller binary size, run above commands with -ldflags="-s -w"

go install -ldflags="-s -w"[email protected]

Other install options

Bash script

Run this command in your terminal:

curl | sudo bash

Manual download

Download the latest release and add the path to your binary into your PATH.

Example commands

# Command structure:
act [<event>] [options]
If no event name passed, will default to "on: push"

# List the actions for the default event:
act -l

# List the actions for a specific event:
act workflow_dispatch -l

# Run the default (`push`) event:

# Run a specific event:
act pull_request

# Run a specific job:
act -j test

# Run in dry-run mode:
act -n

# Enable verbose-logging (can be used with any of the above commands)
act -v

First act run

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 for more information about .actrc and to Runners for information about used/available Docker images.


  -a, --actor string                     user that triggered the event (default "nektos/act")
      --artifact-server-path string      Defines the path where the artifact server stores uploads and retrieves downloads from. If not specified the artifact server will not start.
      --artifact-server-port string      Defines the port where the artifact server listens (will only bind to localhost). (default "34567")
  -b, --bind                             bind working directory to container, rather than copy
      --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.
      --container-cap-add stringArray    kernel capabilities to add to the workflow containers (e.g. --container-cap-add SYS_PTRACE)
      --container-cap-drop stringArray   kernel capabilities to remove from the workflow containers (e.g. --container-cap-drop SYS_PTRACE)
      --container-daemon-socket string   Path to Docker daemon socket which will be mounted to containers (default "/var/run/docker.sock")
      --defaultbranch string             the name of the main branch
      --detect-event                     Use first event type from workflow as event that triggered the workflow
  -C, --directory string                 working directory (default ".")
  -n, --dryrun                           dryrun mode
      --env stringArray                  env to make available to actions with optional value (e.g. --env myenv=foo or --env myenv)
      --env-file string                  environment file to read and use as env in the containers (default ".env")
  -e, --eventpath string                 path to event JSON file
      --github-instance string           GitHub instance to use. Don't use this if you are not using GitHub Enterprise Server. (default "")
  -g, --graph                            draw workflows
  -h, --help                             help for act
      --insecure-secrets                 NOT RECOMMENDED! Doesn't hide secrets while printing logs.
  -j, --job string                       run job
  -l, --list                             list workflows
      --no-recurse                       Flag to disable running workflows from subdirectories of specified path in '--workflows'/'-W' flag
  -P, --platform stringArray             custom image to use per platform (e.g. -P ubuntu-18.04=nektos/act-environments-ubuntu:18.04)
      --privileged                       use privileged mode
  -p, --pull                             pull docker image(s) even if already present
  -q, --quiet                            disable logging of output from steps
      --rebuild                          rebuild local action docker image(s) even if already present
  -r, --reuse                            don't remove container(s) on successfully completed workflow(s) to maintain state between runs
      --rm                               automatically remove container(s)/volume(s) after a workflow(s) failure
  -s, --secret stringArray               secret to make available to actions with optional value (e.g. -s mysecret=foo or -s mysecret)
      --secret-file string               file with list of secrets to read from (e.g. --secret-file .secrets) (default ".secrets")
      --use-gitignore                    Controls whether paths specified in .gitignore should be copied into container (default true)
      --userns string                    user namespace to use
  -v, --verbose                          verbose output
  -w, --watch                            watch the contents of the local repo and run when files change
  -W, --workflows string                 path to workflow file(s) (default "./.github/workflows/")

In case you want to pass a value for ${{ github.token }}, you should pass GITHUB_TOKEN as secret: act -s GITHUB_TOKEN=[insert token or leave blank for secure input].

Known Issues


A MODULE_NOT_FOUND during docker cp command #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:

- name: test action locally
  uses: ./

In this case, you must use actions/[email protected] 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:

  - name: Checkout
    uses: actions/[email protected]
      path: "my-action"

If the path: value doesn't match the name of the repository, a MODULE_NOT_FOUND will be thrown.

docker context support

The current docker context isn't respected (#583).

You can work around this by setting DOCKER_HOST before running act, with e.g:

export DOCKER_HOST=$(docker context inspect --format '{{.Endpoints.docker.Host}}')


GitHub Actions offers managed virtual environments 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:

GitHub Runner Micro Docker Image Medium Docker Image Large Docker Image
ubuntu-latest node:16-buster-slim
ubuntu-20.04 node:16-buster-slim
ubuntu-18.04 node:16-buster-slim

Windows and macOS based platforms are currently unsupported and won't work (see issue #97)

Please see for more information about the Docker images that can be used with act

Default runners are intentionally incomplete

These default images do not contain all the tools that GitHub Actions offers by default in their runners. Many things can work improperly or not at all while running those image. 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 in respective repository (issues with act in this repository, issues with nektos/act-environments-ubuntu:18.04 in nektos/act-environments and issues with any image from user catthehacker in catthehacker/docker_images)

Alternative runner images

If you need an environment that works just like the corresponding GitHub runner then consider using an image provided by nektos/act-environments:

⚠️ 🐘 *** WARNING - this image is >18GB 😱***

Use an alternative runner image

To use a different image for the runner, use the -P option.

act -P <platform>=<docker-image>

If your workflow uses ubuntu-18.04, consider below line as an example for changing Docker image used to run that workflow:

act -P ubuntu-18.04=nektos/act-environments-ubuntu:18.04

If you use multiple platforms in your workflow, you have to specify them to change which image is used. For example, if your workflow uses ubuntu-18.04, ubuntu-16.04 and ubuntu-latest, specify all platforms like below

act -P ubuntu-18.04=nektos/act-environments-ubuntu:18.04 -P ubuntu-latest=ubuntu:latest -P ubuntu-16.04=node:16-buster-slim


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.
  • act --secret-file my.secrets - load secrets values from my.secrets file.
    • secrets file format is the same as .env format


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:

# sample .actrc file
-P ubuntu-latest=nektos/act-environments-ubuntu:18.04

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:

act --env-file my.env


MY_2ND_ENV_VAR="my 2nd env var value"

Skipping steps

Act adds a special environment variable ACT that can be used to skip a step that you don't want to run locally. E.g. a step that posts a Slack message or bumps a version number.

- name: Some step
  if: ${{ !env.ACT }}
  run: |


Every GitHub event 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:

  "pull_request": {
    "head": {
      "ref": "sample-head-ref"
    "base": {
      "ref": "sample-base-ref"
act -e pull-request.json

Act will properly provide github.head_ref and github.base_ref to the action as expected.

GitHub Enterprise

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.

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 for more information on how to use actions.


Need help? Ask on Gitter!


Want to contribute to act? Awesome! Check out the contributing guidelines to get involved.

Manually building from source

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