#github-action #yaml #workflow #json-schema #validation #path #checking

bin+lib action-validator

Validator for GitHub action and workflow YAML files

9 unstable releases

0.6.0 Feb 23, 2024
0.5.4 Nov 24, 2023
0.5.3 Jul 11, 2023
0.5.2 Jun 30, 2023
0.2.1 Jan 6, 2023

#284 in Development tools

38 downloads per month


525 lines

The action-validator is a standalone tool designed to "lint" the YAML files used to define GitHub Actions and Workflows. It ensures that they are well-formed, by checking them against published JSON schemas, and it makes sure that any globs used in paths / paths-ignore match at least one file in the repo.

The intended use case for action-validator is in Git pre-commit hooks and similar situations.


We have many ways to install action-validator.

Pre-built binaries

The GitHub releases have some pre-built binaries -- just download and put them in your path. If a binary for your platform isn't available, let me know and I'll see what I can figure out.

Using cargo

If you've got a Rust toolchain installed, running cargo install action-validator should give you the latest release.

Using asdf

If you're a proponent of the asdf tool, then you can use that to install and manage action-validator:

asdf plugin add action-validator
# or
asdf plugin add action-validator https://github.com/mpalmer/action-validator.git

Install/configure action-validator:

# Show all installable versions
asdf list-all action-validator

# Install specific version
asdf install action-validator latest

# Set a version globally (on your ~/.tool-versions file)
asdf global action-validator latest

# Now action-validator commands are available
action-validator --help

Using NPM

Node users can install the latest version using NPM:

ℹ️ The @action-validator/core package can be used directly within Node.js applications.

npm install -g @action-validator/core @action-validator/cli --save-dev

Building from the repo

If you want to build locally, you'll need to:

  1. Checkout the git repository somewhere;

  2. Grab the SchemaStore submodule, by running git submodule init && git submodule update;

  3. Install a Rust toolchain; and then

  4. run cargo build.


Couldn't be simpler: just pass a file to the program:

action-validator .github/workflows/build.yml

Use action-validator -h to see additional options.


As the intended use-case for action-validator is in pre-commit hooks, it assumes that it is being run from the root of the repository. Glob checking will explode horribly if you run it from a sub-directory of the repo -- or, heaven forfend, outside the repository entirely.

In a GitHub Action

The action-validator can be run in a Github action itself, as a pull request job. See the actions job in the QA workflow, in this repository, as an example of how to use action-validator + asdf in a GitHub workflow. This may seem a little redundant (after all, an action has to be valid in order for GitHub to run it), but this job will make sure that all your other actions are also valid.

Using pre-commit

Update your .pre-commit-config.yaml:

- repo: https://github.com/mpalmer/action-validator
  rev: v0.5.1
    - id: action-validator

Pre-commit hook example

Create an executable file in the .git/hooks directory of the target repository: touch .git/hooks/pre-commit && chmod +x .git/hooks/pre-commit and paste the following example code:

if ! command -v action-validator >/dev/null; then
  echo "action-validator is not installed."
  echo "Installation instructions: https://github.com/mpalmer/action-validator"
  exit 1
echo "Running pre-commit hook for GitHub Actions: https://github.com/mpalmer/action-validator"
for action in $(git diff --cached --name-only --diff-filter=ACM | grep -E '^\.github/(workflows|actions)/.*\.ya?ml$'); do
  if action-validator "$action"; then
    echo "✅ $action"
    echo "❌ $action"
    exit 1
echo "action-validator scanned $scan_count GitHub Actions and found no errors!"

This script will run on every commit to the target repository, whether the github action yaml files are being committed, or not and prevent any commit if there are linting errors.

# All action-validator linting errors must be resolved before any commit will succeed.
$ echo "" >> README.md && git add README.md && git commit -m "Update read-me"
Running pre-commit hook for GitHub Actions: https://github.com/mpalmer/action-validator
Validation failed: ValidationState {
    errors: [
        Properties {
            path: "",
            detail: "Additional property 'aname' is not allowed",
    missing: [],
    replacement: None,
Fatal error validating .github/workflows/ci.yaml: validation failed

# Fix error and try again
$ echo "" >> README.md && git add README.md && git commit -m "Update read-me"
Running pre-commit hook for GitHub Actions: https://github.com/mpalmer/action-validator.github/workflows/ci.yaml
✅ .github/workflows/release.yml
action-validator scanned 2 GitHub Actions found no errors!
[main c34fda3] Update read-me
 1 file changed, 2 insertions(+)


Provided you have followed the installation instructions for NPM, you can run the action validator CLI as follows

npx action-validator <path_to_action_yaml>

Or, if you've installed the package globally:

action-validator <path_to_action_yaml>

Node API

The Node API can be used to validate action and workflow files from Node.js as follows:

⚠️ The Node API does not currently support glob validation.

import { readFileSync } from "fs";
import { validateAction, validateWorkflow } from "@action-validator/core";

// Validate Action
const actionSource = readFileSync("action.yml", "utf8");
const state = validator.validateAction(actionSource);
const isValid = state.errors.length === 0;

// Validate Workflow
const workflowSource = readFileSync("workflow.yml", "utf8");
const state = validator.validateWorkflow(workflowSource);
const isValid = state.errors.length === 0;


Please see CONTRIBUTING.md.


Unless otherwise stated, everything in this repo is covered by the following copyright notice:

Copyright (C) 2021  Matt Palmer <matt@hezmatt.org>

This program is free software: you can redistribute it and/or modify it
under the terms of the GNU General Public License version 3, as
published by the Free Software Foundation.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program.  If not, see <http://www.gnu.org/licenses/>.


~374K SLoC