How to Run GitHub Actions Locally Using the act CLI Tool

GitHub Actions help automate tasks like building, testing, and deploying in your GitHub repository.

With one click, you can publish your production-ready code or package on npm, GitHub pages, docker images, deploy your production code on a cloud provider, and so on.

The problem starts when you're testing GitHub Actions. It can be time-consuming and painful. First, you have to change the GitHub Actions file locally, push your local code into your GitHub repository, and wait for the result.

To solve this issue, You can use the act CLI tool to test and write the GitHub action locally. With act CLI, you do not need to commit/push your local code to the GitHub Repository. You test GitHub action locally on your laptop or machine.

Here are the steps involved:

How to install act.
How to configure and initialize the act CLI.
How to use the act CLI tool.

How to Install `act` for GitHub Actions

The act CLI tool works with Docker. Before starting with act CLI, First, install Docker on your system or laptop.

To install the act CLI, you need to run the following command:

# Window
choco install act-cli

# MacOS
brew install act

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

How to Configure and Initialize the `act` CLI

After the act CLI installation is successful on your laptop or machine, the next step is to run it in your project.

act CLI asks which Docker image size—large, medium, or micro—must be installed during installation.

There are various Docker image sizes:

The Docker Micro image size is 200 MB, and small projects use it.
The Docker Medium image size is 500 MB, and Big Project uses it.
The Docker Large image size is 17 GB, and Enterprise uses it.

The act CLI uses the Docker image to run the GitHub action locally.

$ act

The command output in the terminal looks like this:

$ test-github-actions git:(main) ✗ act
? Please choose the default image you want to use with act:
  - Large size image: ca. 17GB download + 53.1GB storage, you will need 75GB of free disk space, snapshots of GitHub Hosted Runners without snap and pulled docker images
  - Medium size image: ~500MB, includes only necessary tools to bootstrap actions and aims to be compatible with most actions
  - Micro size image: <200MB, contains only NodeJS required to bootstrap actions, doesn't work with all actions

Default image and other options can be changed manually in ~/.actrc (please refer to https://github.com/nektos/act#configuration for additional information about file structure) Micro
[Build Ghost and test theme/install] 🚀  Start image=node:16-buster-slim
INFO[0023] Parallel tasks (0) below minimum, setting to 1 
[Build Ghost and test theme/install]   🐳  docker pull image=node:16-buster-slim platform= username= forcePull=true
INFO[0031] Parallel tasks (0) below minimum, setting to 1 
[Build Ghost and test theme/install]   🐳  docker create image=node:16-buster-slim platform= entrypoint=["tail" "-f" "/dev/null"] cmd=[] network="host"
[Build Ghost and test theme/install]   🐳  docker run image=node:16-buster-slim platform= entrypoint=["tail" "-f" "/dev/null"] cmd=[] network="host"
[Build Ghost and test theme/install]   ☁  git clone 'https://github.com/vimtor/action-zip' # ref=v1.2
[Build Ghost and test theme/install]   ☁  git clone 'https://github.com/softprops/action-gh-release' # ref=v0.1.15
[Build Ghost and test theme/install] ⭐ Run Main actions/checkout@v4
[Build Ghost and test theme/install]   🐳  docker cp src=/home/officialrajdeepsingh/medium/test-github-actions/. dst=/home/officialrajdeepsingh/medium/test-github-actions
[Build Ghost and test theme/install]   ✅  Success - Main actions/checkout@v4
[Build Ghost and test theme/install] ⭐ Run Main Easy Zip Files
[Build Ghost and test theme/install]   🐳  docker cp src=/home/officialrajdeepsingh/.cache/act/vimtor-action-zip@v1.2/ dst=/var/run/act/actions/vimtor-action-zip@v1.2/
[Build Ghost and test theme/install]   🐳  docker exec cmd=[node /var/run/act/actions/vimtor-action-zip@v1.2/dist/index.js] user= workdir=
| Ready to zip "build/ home.txt" into example.zip
|   - build/
|   - home.txt
| 
| Zipped file example.zip successfully
[Build Ghost and test theme/install]   ✅  Success - Main Easy Zip Files
[Build Ghost and test theme/install] Cleaning up container for job install
[Build Ghost and test theme/install] 🏁  Job succeeded

After downloading the image from the Docker repository, the act CLI runs the GitHub action.

act CLI generates the ~/.actrc file in the laptop for configuration. The ~/.actrc file contains the Docker image name.

# .actrc
-P ubuntu-latest=node:16-buster-slim
-P ubuntu-22.04=node:16-bullseye-slim
-P ubuntu-20.04=node:16-buster-slim
-P ubuntu-18.04=node:16-buster-slim

To install other Docker images, remove the ~/.actrc file and re-run the act CLI to install the different Docker images.

Error

Due to dependence on Docker, we may face some errors when initializing an act CLI for the first time.

$ act

The error should look like this:

$ test-github-actions git:(main) ✗ act       
ERRO[0000] daemon Docker Engine socket not found and containerDaemonSocket option was not set 
? Please choose the default image you want to use with act:
  - Large size image: ca. 17GB download + 53.1GB storage, you will need 75GB of free disk space, snapshots of GitHub Hosted Runners without snap and pulled docker images
  - Medium size image: ~500MB, includes only necessary tools to bootstrap actions and aims to be compatible with most actions
  - Micro size image: <200MB, contains only NodeJS required to bootstrap actions, doesn't work with all actions

Default image and other options can be changed manually in ~/.actrc (please refer to https://github.com/nektos/act#configuration for additional information about file structure) Micro
[Build Ghost and test theme/install] 🚀  Start image=node:16-buster-slim
INFO[0305] Parallel tasks (0) below minimum, setting to 1 
[Build Ghost and test theme/install]   🐳  docker pull image=node:16-buster-slim platform= username= forcePull=true
Error: Cannot connect to the Docker daemon at unix:///var/run/docker.sock. Is the docker daemon running?

You're seeing the Cannot connect to the Docker daemon error in the above code. This issue occurs due to the Docker daemon. In simple words, the Docker daemon is not running. You can resolve this issue by starting your Docker and re-running your act command.

There are two ways to run Docker services.

Open Docker desktop in your window, and your Docker service is started.
Run Docker with the systemctl start docker command on Linux.

You can verify whether your Docker is running or not with the following command:

$ systemctl status docker

● docker.service - Docker Application Container Engine
     Loaded: loaded (/etc/systemd/system/docker.service; enabled; preset: enabled)
    Drop-In: /nix/store/fibzdkfv6in4xw39rm0c7bq4nadzisas-system-units/docker.service.d
             └─overrides.conf
     Active: active (running) since Mon 2024-02-26 12:38:37 IST; 3h 39min ago
TriggeredBy: ● docker.socket
       Docs: https://docs.docker.com
   Main PID: 1186 (dockerd)
         IP: 0B in, 0B out
         IO: 109.0M read, 152.0K written
      Tasks: 40
     Memory: 148.5M
        CPU: 1min 40.817s
     CGroup: /system.slice/docker.service
             ├─1186 /nix/store/7pzis8dkhs461kl1bg2fp0202dw6r5i5-moby-24.0.5/libexec/docker/dockerd --config-file=/nix/store/3rlv5f0zldcc120b01szywidl0qz9x4p-daemon.json
             └─1256 containerd --config /var/run/docker/containerd/containerd.toml

Feb 26 12:38:37 nixos dockerd[1256]: time="2024-02-26T12:38:37.532987858+05:30" level=info msg="containerd successfully booted in 0.016901s"
Feb 26 12:38:37 nixos dockerd[1186]: time="2024-02-26T12:38:37.562515048+05:30" level=info msg="[graphdriver] using prior storage driver: overlay2"
Feb 26 12:38:37 nixos dockerd[1186]: time="2024-02-26T12:38:37.564062690+05:30" level=info msg="Loading containers: start."
Feb 26 12:38:37 nixos dockerd[1186]: time="2024-02-26T12:38:37.778478313+05:30" level=info msg="Default bridge (docker0) is assigned with an IP address 172.17.0.0/16. Daemon option --bip can be used to set a preferred IP address"
Feb 26 12:38:37 nixos dockerd[1186]: time="2024-02-26T12:38:37.805931545+05:30" level=info msg="Loading containers: done."
Feb 26 12:38:37 nixos dockerd[1186]: time="2024-02-26T12:38:37.828589904+05:30" level=info msg="Docker daemon" commit=v24.0.5 graphdriver=overlay2 version=24.0.5
Feb 26 12:38:37 nixos dockerd[1186]: time="2024-02-26T12:38:37.828929197+05:30" level=info msg="Daemon has completed initialization"
Feb 26 12:38:37 nixos systemd[1]: Started Docker Application Container Engine.
Feb 26 12:38:37 nixos dockerd[1186]: time="2024-02-26T12:38:37.841992729+05:30" level=info msg="API listen on /run/docker.sock"
Feb 26 12:38:37 nixos dockerd[1186]: time="2024-02-26T12:38:37.841993669+05:30" level=info msg="API listen on /run/docker.sock"

How to Use the `act` CLI Tool

act CLI has many options, but we'll look at some important ones. You can check all the options by running the act --help command.

`act` CLI Options

Here are some act CLI options:

Events
Lists
Running Specific Jobs
Graph
Environment Variables
Secrets

Events

act CLI's default action is the push action, which triggers only push events by default.

$ act

You can change the event after passing the second argument, which is the name of your action. In our case, we'll pass pull_request.

$ act pull_request

There is a long list available to trigger workflows. You can read it on the GitHub action documentation.

Lists

The list option prints all the available jobs that you write in .github/workflows.

$ act -l

The command output in the terminal looks like this.

$ act -l    
Stage  Job ID             Job name           Workflow name                  Workflow file      Events      
0      zip                zip                Convert files into Zip         build-project.yml  release     
0      request_test       request_test       Pull Request                   fork.yml           fork        
0      pull_request_test  pull_request_test  Pull Request                   issues.yml         issues      
0      show               show               Convert files into Zip folder  test.yml           pull_request

Running Specific Jobs

You use the --job option command to run specific jobs from your workflows.

Make sure your job name is unique – otherwise, it runs all jobs containing the same in your workflow. Whenever you can not pass an event by default, trigger the push event.

Syntax

act --job <name-of-your-job>

For example, we run a specific show job.

$ act --job 'show'

Graph

The graph option draws the available workflow jobs structure in your terminal as a graph.

$ act --graph

The command output in the terminal looks like this:

$ act --graph
 ╭─────╮ ╭──────────────╮ ╭───────────────────╮ ╭──────╮
 │ zip │ │ request_test │ │ pull_request_test │ │ show │
 ╰─────╯ ╰──────────────╯ ╰───────────────────╯ ╰──────╯

Environment Variables

Using environment variables with the act CLI is easy. You only need to create a new .env file. act CLI automatically loads the environment that is available in the .env file. For example, we add a ENV_ID variables.

# .env

ENV_ID='My Env'

To use the ENV_ID environment variables, use the following syntax ${{ env.ENV_ID }} in your GitHub action:

# .github/workflows/test.yml

name: Convert files into Zip folder

on: pull_request

jobs:
  show:
    runs-on: ubuntu-latest
    steps:
      - name: Show Env
        run: echo "Env ${{ env.ENV_ID }}"

With the --env-file option, you can change the default .env file name to my-custom.env file.

$ act --env-file=my-custom.env

Secrets

You must create a new .secrets file to load the environment secrets with the act CLI. This automatically loads the environment secrets that are available in the secrets file. For example, we add a APP_SECRET and APP_ID variables.

APP_SECRET='7824jurd789gyu45esxgfgf48822166974gtredsyujn'
APP_ID='7878974561587'

To use the APP_SECRET environment variables, use the following syntax ${{ secrets.APP_SECRE}} in your GitHub action:

# .github/workflows/test.yml

name: Learn environment secrets 

on: pull_request

jobs:
  show:
    runs-on: ubuntu-latest
    steps:
      - name: Show env
        run: echo "App SECRET ${{ secrets.APP_SECRET }}"
      - name: Show varibale
        run: echo "App ID ${{ secrets.APP_ID }}"

You can load your custom my-custom.secrets file containing all your secrets with the --secret-file option.

$ act --secret-file=my-custom.secrets

Conclusion

act CLI helps save time and energy when working and testing GitHub locally. Currently, there is no alternative to act CLI, which allows us to run GitHub actions locally.

act CLI isn't fully compatible with GitHub actions. Some features are not implemented, for example, concurrency, no vars context, incomplete github context, and so on.

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How to Install act for GitHub Actions

How to Configure and Initialize the act CLI