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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!



To install with Homebrew, run:

brew install nektos/tap/act

Alternatively, you can use the following:

curl | sudo bash

If you are running Windows, download the latest release and add the binary into your PATH.
If you are using Chocolatey then run:
choco install act-cli

If you are using Scoop then run:
scoop install act

If you are running Arch Linux, you can install the act package with your favorite package manager:

yay -S act

If you are using NixOS or the Nix package manager on another platform you can install act globally by running

nix-env -iA nixpkgs.act

or in a shell by running

nix-shell -p act


# List the actions
act -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


  -b, --bind                   bind working directory to container, rather than copy
  -C, --directory string       working directory (default ".")
  -n, --dryrun                 dryrun mode
      --env-file string        environment file to read (default ".env")
  -e, --eventpath string       path to event JSON file
  -h, --help                   help for act
  -j, --job string             run job
  -l, --list                   list workflows
  -P, --platform stringArray   custom image to use per platform (e.g. -P ubuntu-18.04=nektos/act-environments-ubuntu:18.04)
  -p, --pull                   pull docker image(s) if already present
  -q, --quiet                  disable logging of output from steps
  -r, --reuse                  reuse action containers to maintain state
  -s, --secret stringArray     secret to make available to actions with optional value (e.g. -s mysecret=foo or -s mysecret)
      --secret-file            file with list of secrets to read from (e.g. --secret-file .secrets)
  -v, --verbose                verbose output
      --version                version for act
  -w, --watch                  watch the contents of the local repo and run when files change
  -W, --workflows string       path to workflow files (default "./.github/workflows/")

Known Issues

MODULE_NOT_FOUND during docker cp command #228

  - name: Checkout
    uses: actions/checkout@v2
      path: "your-action-root-directory"


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:

GitHub Runner Docker Image
ubuntu-latest node:12.6-buster-slim
ubuntu-18.04 node:12.6-buster-slim
ubuntu-16.04 node:12.6-stretch-slim
windows-latest unsupported
windows-2019 unsupported
macos-latest unsupported
macos-10.15 unsupported

Default runners are intentionally incomplete

These default images do not contain all the tools that GitHub Actions offers by default in their runners.

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


To run act with secrets, you can enter them interactively or supply them as environment variables. 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:

# 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


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.


Need help? Ask on Gitter!


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

Building from source

  • Install Go tools 1.11.4+ - (
  • Clone this repo git clone
  • Pull the default docker image docker pull nektos/act-environments-ubuntu:18.04
  • Run unit tests with make test
  • Build and install: make install
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