Contribute to the CI/CD Schema

The pipeline editor uses a CI/CD schema to enhance the authoring experience of our CI/CD configuration files. With the CI/CD schema, the editor can:

• Validate the content of the CI/CD configuration file as it is being written in the editor.
• Provide autocomplete functionality and suggest available keywords.
• Provide definitions of keywords through annotations.

As the rules and keywords for configuring our CI/CD configuration files change, so too should our CI/CD schema.

JSON Schemas

The CI/CD schema follows the JSON Schema Draft-07 specification. Although the CI/CD configuration file is written in YAML, it is converted into JSON by using monaco-yaml before it is validated by the CI/CD schema.

If you're new to JSON schemas, consider checking out this guide for a step-by-step introduction on how to work with JSON schemas.

Update Keywords

The CI/CD schema is at app/assets/javascripts/editor/schema/ci.json. It contains all the keywords available for authoring CI/CD configuration files. Check the CI/CD YAML syntax reference for a comprehensive list of all available keywords.

All keywords are defined under definitions. We use these definitions as references to share common data structures across the schema.

For example, this defines the retry keyword:

{
  "definitions": {
    "retry": {
      "description": "Retry a job if it fails. Can be a simple integer or object definition.",
      "oneOf": [
        {
          "$ref": "#/definitions/retry_max"
        },
        {
          "type": "object",
          "additionalProperties": false,
          "properties": {
            "max": {
              "$ref": "#/definitions/retry_max"
            },
            "when": {
              "description": "Either a single or array of error types to trigger job retry.",
              "oneOf": [
                {
                  "$ref": "#/definitions/retry_errors"
                },
                {
                  "type": "array",
                  "items": {
                    "$ref": "#/definitions/retry_errors"
                  }
                }
              ]
            }
          }
        }
      ]
    }
  }
}

With this definition, the retry keyword is both a property of the job_template definition and the default global keyword. Global keywords that configure pipeline behavior (such as workflow and stages) are defined under the topmost properties key.

{
  "properties": {
    "default": {
      "type": "object",
      "properties": {
        "retry": {
          "$ref": "#/definitions/retry"
        },
      }
    }
  },
  "definitions": {
    "job_template": {
      "properties": {
        "retry": {
          "$ref": "#/definitions/retry"
        }
      },
    }
  }
}

Guidelines for updating the schema

• Keep definitions atomic when possible, to be flexible with referencing keywords. For example, workflow:rules uses only a subset of properties in the rules definition. The rules properties have their own definitions, so we can reference them individually.
• When adding new keywords, consider adding a description with a link to the keyword definition in the documentation. This information shows up in the annotations when the user hovers over the keyword.
• For each property, consider if a minimum, maximum, or default values are required. Some values might be required, and in others we can set blank. In the blank case, we can add the following to the definition:

{
  "keyword": {
    "oneOf": [
      {
        "type": "null"
      },
      ...
    ]
  }
}

Test the schema

Verify changes

1. Go to CI/CD > Editor.
2. Write your CI/CD configuration in the editor and verify that the schema validates it correctly.

Write specs

All of the CI/CD schema specs are in spec/frontend/editor/schema/ci. Legacy tests are in JSON, but we recommend writing all new tests in YAML. You can write them as if you're adding a new .gitlab-ci.yml configuration file.

Tests are separated into positive tests and negative tests. Positive tests are snippets of CI/CD configuration code that use the schema keywords as intended. Conversely, negative tests give examples of the schema keywords being used incorrectly. These tests ensure that the schema validates different examples of input as expected.

ci_schema_spec.js is responsible for running all of the tests against the schema.

A detailed explanation of how the tests are set up can be found in this merge request.

Update schema specs

If a YAML test does not exist for the specified keyword, create new files in yaml_tests/positive_tests and yaml_tests/negative_tests. Otherwise, you can update the existing tests:

1. Write both positive and negative tests to validate different kinds of input.

2. If you created new files, import them in ci_schema_spec.js and add each file to their corresponding object entries. For example:

   import CacheYaml from './yaml_tests/positive_tests/cache.yml';
   import CacheNegativeYaml from './yaml_tests/negative_tests/cache.yml';
   
   // import your new test files
   import NewKeywordTestYaml from './yaml_tests/positive_tests/cache.yml';
   import NewKeywordTestNegativeYaml from './yaml_tests/negative_tests/cache.yml';
   
   describe('positive tests', () => {
     it.each(
       Object.entries({
         CacheYaml,
         NewKeywordTestYaml, // add positive test here
       }),
     )('schema validates %s', (_, input) => {
       expect(input).toValidateJsonSchema(schema);
     });
   });
   
   describe('negative tests', () => {
     it.each(
       Object.entries({
         CacheNegativeYaml,
         NewKeywordTestYaml, // add negative test here
       }),
     )('schema validates %s', (_, input) => {
       expect(input).not.toValidateJsonSchema(schema);
     });
   });

3. Run the command yarn jest spec/frontend/editor/schema/ci/ci_schema_spec.js and verify that all the tests successfully pass.

If the spec covers a change to an existing keyword and it affects the legacy JSON tests, update them as well.