This GitHub Actions workflow creates three jobs to test, build and scan a Docker image for security vulnerabilities, which are then uploaded to GitHub's registry. The test job runs on Ubuntu 18.x, installs Node.js environment, installs dependencies and runs tests. The build job builds the Docker image using the `docker/build-push-action` and pushes it to GitHub's Docker registry. The scan job scans the Docker image for security vulnerabilities using Snyk and uploads the vulnerability report to GitHub. The workflow uses environment variables to specify the Docker image's tag, repository and registry, allowing it to be easily customized for different projects.