Tutorial: Lint code using a GitHub Action

In this tutorial, you add the Super-Linter GitHub Action to an Amazon CodeCatalyst workflow. The Super-Linter action inspects code, finds areas where the code has errors, formatting issues, and suspicious constructs, and then outputs the results to the CodeCatalyst console). After adding the linter to your workflow, you run the workflow to lint a sample Node.js application (app.js). You then fix the reported problems and run the workflow again to see if the fixes worked.

Tip

Consider using Super-Linter to lint YAML files, such as AWS CloudFormation templates.

Prerequisites

Before you begin, you'll need:

• A CodeCatalyst space with a connected AWS account. For more information, see Creating a space.

• An empty project in your CodeCatalyst space called codecatalyst-linter-project. Choose the Start from scratch option to create this project.

  For more information, see Creating an empty project in Amazon CodeCatalyst.

Step 1: Create a source repository

In this step, you create a source repository in CodeCatalyst. You'll use this repository to store the sample application source file, app.js, for this tutorial.

For more information about source repositories, see Creating a source repository.

To create a source repository

1. Open the CodeCatalyst console at https://codecatalyst.aws/.

2. Navigate to your project, codecatalyst-linter-project.

3. In the navigation pane, choose Code, and then choose Source repositories.

4. Choose Add repository, and then choose Create repository.

5. In Repository name, enter:

   codecatalyst-linter-source-repository

6. Choose Create.

Step 2: Add an app.js file

In this step, you add an app.js file to your source repository. The app.js contains function code that has a few mistakes that the linter will find.

To add the app.js file

1. In the CodeCatalyst console, choose your project, codecatalyst-linter-project.

2. In the navigation pane, choose Code, and then choose Source repositories.

3. From the list of source repositories, choose your repository, codecatalyst-linter-source-repository.

4. In Files, choose Create file.

5. In the text box, enter the following code:

   // const axios = require('axios')
   // const url = 'http://checkip.amazonaws.com/';
   let response;
   /**
    *
    * Event doc: https://docs.aws.amazon.com/apigateway/latest/developerguide/set-up-lambda-proxy-integrations.html#api-gateway-simple-proxy-for-lambda-input-format
    * @param {Object} event - API Gateway Lambda Proxy Input Format
    *
    * Context doc: https://docs.aws.amazon.com/lambda/latest/dg/nodejs-prog-model-context.html 
    * @param {Object} context
    *
    * Return doc: https://docs.aws.amazon.com/apigateway/latest/developerguide/set-up-lambda-proxy-integrations.html
    * @returns {Object} object - API Gateway Lambda Proxy Output Format
    *
    */
   exports.lambdaHandler = async (event, context) => {
     try {
       // const ret = await axios(url);
       response = {
         statusCode: 200,
         'body': JSON.stringify({
           message: 'hello world'
           // location: ret.data.trim()
         })
       }
     } catch (err) {
       console.log(err)
       return err
     }
   
       return response
   }

6. For File name, enter app.js. Keep the other default options.

7. Choose Commit.

   You have now created a file called app.js.

Step 3: Create a workflow that runs the Super-Linter action

In this step, you create a workflow that runs the Super-Linter action when you push code to your source repository. The workflow consists of the following building blocks, which you define in a YAML file:

• A trigger – This trigger starts the workflow run automatically when you push a change to your source repository. For more information about triggers, see Starting a workflow run automatically using triggers.

• A 'GitHub Actions' action – On trigger, the GitHub Actions action runs the Super-Linter action, which in turn inspects all files in your source repository. If the linter finds an issue, the workflow action fails.

To create a workflow that runs the Super-Linter action

1. In the CodeCatalyst console, choose your project, codecatalyst-linter-project.

2. In the navigation pane, choose CI/CD, and then choose Workflows.

3. Choose Create workflow.

4. For Source repository, choose codecatalyst-linter-source-repository.

5. For Branch, choose main.

6. Choose Create.

7. Delete the YAML sample code.

8. Add the following YAML:

   Name: codecatalyst-linter-workflow
   SchemaVersion: "1.0"
   Triggers:
     - Type: PUSH
       Branches:
         - main
   Actions:
     SuperLinterAction:
       Identifier: aws/github-actions-runner@v1
       Configuration:
         Steps:
           github-action-code

   In the preceding code, replace github-action-code with the Super-Linter action code, as instructed in the following steps of this procedure.

9. Go to the Super-Linter page in the GitHub Marketplace.

10. Under steps:(lowercase), find the code and paste it into the CodeCatalyst workflow under Steps: (uppercase).

    Adjust the GitHub Action code to conform to CodeCatalyst standards, as shown in the following code.

    Your CodeCatalyst workflow now looks like this:

    Name: codecatalyst-linter-workflow
    SchemaVersion: "1.0"
    Triggers:
      - Type: PUSH
        Branches:
          - main
    Actions:
      SuperLinterAction:
        Identifier: aws/github-actions-runner@v1
        Configuration:
          Steps:
            - name: Lint Code Base
              uses: github/super-linter@v4
              env:
                VALIDATE_ALL_CODEBASE: "true"
                DEFAULT_BRANCH: main

11. (Optional) Choose Validate to make sure the YAML code is valid before committing.

12. Choose Commit, enter a Commit message, select your codecatalyst-linter-source-repository Repository, and choose Commit again.

    You have now created a workflow. A workflow run starts automatically because of the trigger defined at the top of the workflow.

To view the workflow run in progress

1. In the navigation pane, choose CI/CD, and then choose Workflows.

2. Choose the workflow you just created: codecatalyst-linter-workflow.

3. In the workflow diagram, choose SuperLinterAction.

4. Wait for the action to fail. This failure is expected because the linter found problems in the code.

5. Leave the CodeCatalyst console open and go to Step 4: Fix problems that the Super-Linter found.

Step 4: Fix problems that the Super-Linter found

The Super-Linter should have found problems in the app.js code, as well as the README.md file included in your source repository.

To fix the problems the linter found

1. In the CodeCatalyst console, choose the Logs tab, and then choose Lint Code Base.

   The logs that the Super-Linter action generated are displayed.

2. In the Super-Linter logs, scroll down to around line 90, where you find the start of the problems. They look similar to the following:

   /github/workspace/hello-world/app.js:3:13: Extra semicolon.
   /github/workspace/hello-world/app.js:9:92: Trailing spaces not allowed.
   /github/workspace/hello-world/app.js:21:7: Unnecessarily quoted property 'body' found.
   /github/workspace/hello-world/app.js:31:1: Expected indentation of 2 spaces but found 4.
   /github/workspace/hello-world/app.js:32:2: Newline required at end of file but not found.

3. Fix app.js and README.md in your source repository and commit your changes.

   Tip

   To fix the README.md, add markdown to the code block, like this:

   ```markdown
   Setup examples:
   ...
   ```

   Your changes start another workflow run automatically. Wait for the workflow to finish. If you fixed all the problems, the workflow should succeed.

Clean up

Clean up in CodeCatalyst to remove traces of this tutorial from your environment.

To clean up in CodeCatalyst

1. Open the CodeCatalyst console at https://codecatalyst.aws/.

2. Delete codecatalyst-linter-source-repository.

3. Delete codecatalyst-linter-workflow.

In this tutorial, you learned how to add the Super-Linter GitHub Action to a CodeCatalyst workflow in order to lint some code.