Overview

"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!

Installation

To install with Homebrew, run:

brew install act

Alternatively, you can use the following:

curl https://raw.githubusercontent.com/nektos/act/master/install.sh | sudo bash

NOTE: Currently not compatible with Apple Silicon (ARM). This project relies on Docker which has not been ported to Apple Silicon yet.

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

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:
act

# 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.

Flags

  -a, --actor string                    user that triggered the event (default "nektos/act")
  -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.
      --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. --e myenv=foo or -s 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
  -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
  -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
  -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 string              file with list of secrets to read from (e.g. --secret-file .secrets) (default ".secrets")
      --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/")

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/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:

steps:
  - name: Checkout
    uses: actions/checkout@v2
    with:
      path: "my-action"

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

Runners

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:12.20.1-buster-slim	catthehacker/ubuntu:act-latest	unavailable
ubuntu-20.04	node:12.20.1-buster-slim	catthehacker/ubuntu:act-20.04	unavailable
ubuntu-18.04	node:12.20.1-buster-slim	catthehacker/ubuntu:act-18.04	nektos/act-environments-ubuntu:18.04
ubuntu-16.04	node:12.20.1-stretch-slim	catthehacker/ubuntu:act-16.04	unavailable

Below platforms are currently unsupported and won't work (see issue #97)

• windows-latest
• windows-2019
• macos-latest
• macos-10.15

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.

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:

• nektos/act-environments-ubuntu:18.04 - built from the Packer file GitHub uses in actions/virtual-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:12.20.1-buster-slim

Secrets

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

Configuration

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

.env:

MY_ENV_VAR=MY_ENV_VAR_VALUE
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: |
    ...    

Events

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.

Support

Need help? Ask on Gitter!

Contributing

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

Building from source

• Install Go tools 1.16+ - (https://golang.org/doc/install)
• Clone this repo git clone git@github.com:nektos/act.git
• Pull the default docker image docker pull nektos/act-environments-ubuntu:18.04
• Run unit tests with make test
• Build and install: make install