Feature Focus: How to use Github Actions to scan your applications with CAST Highlight

Github Actions are workflows that you can use on your application repositories based on specific triggers. This is the perfect place to run CAST Highlight scans in an automated fashion. This article explains how to get a CAST Highlight action from Github Action marketplace and customize it to your needs.

The CAST Highlight action can be defined in your Github app repositories and will perform instant or scheduled scans of the code base. It uses a dynamically provisioned Docker container from Github and publishes scan results to the CAST Highlight portal. The magic really happens when you realize you can automate CAST Highlight scans as part of your Github workflow without needing any specific scripting or Docker skills!

How it works

The CAST Highlight action has three main elements:

  • The action script (action.yml) which contains the different steps, the events that will trigger the action and the scope (e.g. branches) of the action on the repository
  • Some environment variables attached to your repository which contain CAST Highlight identifiers for the application
  • A secret variable at the repository level which contains your user authentication token

Let’s see the content of an action in detail to learn how to customize it for your needs.

In our Github Action that you can download from the marketplace, the CAST Highlight scan is scheduled to happen twice a month, the typical duration of a development sprint.


name: CAST Highlight Scan
      - cron: 0 6 1,15 * *

Here, we define a trigger to run the action based on a scheduled cron expression. The action will be performed at minute 0 of 6th hour (6am), on 1st and 15th days of the month. This website can help you with writing your cron if you’re not familiar with this syntax: https://crontab.guru/#0_6_5,15_*_*

Github Actions support other triggers like manual launch (workflow_dispatch) or based on specific events like push or pull requests. You can find all configurable events available from this page: https://docs.github.com/en/actions/reference/events-that-trigger-workflows#example-workflow-configuration

The next section of the script is dedicated to dynamically provision a Docker container running on Github and check out your repository to run the CAST Highlight scan.


    runs-on: ubuntu-latest
    environment: prod

Github offers Github-hosted runners in various operating systems (see the list here), depending on your needs. In our case, we use Linux Ubuntu to run the command line.

Then, we add a step that will perform a checkout on the repository. We use a ready-to-go action from the action marketplace called Checkout (https://github.com/marketplace/actions/checkout).


      - uses: actions/checkout@v2

The next step is about getting CAST Highlight variables that the command line will use to automatically upload scan results to the right application on the CAST Highlight portal.


      - name: get company and application ids
        run: |
          cat .github/workflows/hl.env >> $GITHUB_ENV

These variable need to be listed in an hl.env file you will add to your repository in the “.github/workflows” folder.

Finally, the last step is about passing information to the Docker image of the CAST Highlight command line as follows:


      - name: scan project source code
        run: |
          docker run --rm -v $(pwd):/s -v /tmp:/w  casthighlight/hl-agent-cli \
                             --sourceDir /s \
                             --workingDir /w \
                             --tokenAuth ${{ secrets.CAST_HIGHLIGHT_API_TOKEN }} \
                             --companyId ${{ env.companyId }} \
                             --applicationId ${{ env.applicationId }} \
                             --serverUrl ${{ env.serverUrl }}

If you’re familiar with the CAST Highlight command line interface and/or the Docker image of the command line, you’ll see the common CAST Highlight options for specifying the scan and upload options.

For security purposes, we recommend storing the user authentication token in a secret variable associated with your Github repository. To add a secret, simply go to the Settings > Secrets tab of your repository and create a “CAST_HIGHLIGHT_API_TOKEN” with your user token. Learn how to get your CAST Highlight user token from this article: https://doc.casthighlight.com/feature-focus-api-cli-user-token-management/

As soon as a scan job is run, you can monitor how it’s going through the action logs as shown below.

Obviously, this action example is a starting point. You can add other command line options and job steps to fit your needs.