134 lines
5.4 KiB
Markdown
134 lines
5.4 KiB
Markdown
---
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type: reference, howto
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disqus_identifier: 'https://docs.gitlab.com/ee/user/project/merge_requests/code_quality_diff.html'
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---
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# Code Quality **(STARTER)**
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> [Introduced](https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/1984)
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in [GitLab Starter](https://about.gitlab.com/pricing/) 9.3.
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With the help of [GitLab CI/CD](../../../ci/README.md), you can analyze your
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source code quality using GitLab Code Quality.
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Code Quality:
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- Uses [Code Climate Engines](https://codeclimate.com), which are
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free and open source. Code Quality doesn't require a Code Climate
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subscription.
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- Runs in [pipelines](../../../ci/pipelines.md) using an Docker image built in
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[GitLab Code
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Quality](https://gitlab.com/gitlab-org/security-products/codequality) project.
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- Can make use of a [template](#template-and-examples).
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- Is available with [Auto
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DevOps](../../../topics/autodevops/index.md#auto-code-quality-starter).
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Going a step further, GitLab can show the Code Quality report right
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in the merge request widget area:
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![Code Quality Widget](img/code_quality.gif)
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## Use cases
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For instance, consider the following workflow:
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1. Your backend team member starts a new implementation for making a certain
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feature in your app faster.
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1. With Code Quality reports, they analyze how their implementation is impacting
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the code quality.
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1. The metrics show that their code degrade the quality in 10 points.
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1. You ask a co-worker to help them with this modification.
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1. They both work on the changes until Code Quality report displays no
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degradations, only improvements.
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1. You approve the merge request and authorize its deployment to staging.
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1. Once verified, their changes are deployed to production.
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## Template and examples
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For most GitLab instances, the supplied template is the preferred method of
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implementing Code Quality. See
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[Analyze your project's Code Quality](../../../ci/examples/code_quality.md) for:
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- Information on the builtin GitLab Code Quality template.
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- Examples of manual GitLab configuration for earlier GitLab versions.
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## Configuring jobs using variables
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The Code Quality job supports environment variables that users can set to
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configure job execution at runtime.
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For a list of available environment variables, see
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[Environment variables](https://gitlab.com/gitlab-org/security-products/codequality/blob/master/README.md#environment-variables).
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## Implementing a custom tool
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It's possible to have a custom tool provide Code Quality reports in GitLab. To
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do this:
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1. Define a job in your `.gitlab-ci.yml` file that generates the
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[Code Quality report
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artifact](../../../ci/yaml/README.md#artifactsreportscodequality-starter).
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1. Configure your tool to generate the Code Quality report artifact as a JSON
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file that implements subset of the [Code Climate
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spec](https://github.com/codeclimate/spec/blob/master/SPEC.md#data-types).
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The Code Quality report artifact JSON file must contain an array of objects
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with the following properties:
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| Name | Description |
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| ---------------------- | -------------------------------------------------------------------------------------- |
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| `description` | A description of the code quality violation. |
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| `fingerprint` | A unique fingerprint to identify the code quality violation. For example, an MD5 hash. |
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| `location.path` | The relative path to the file containing the code quality violation. |
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| `location.lines.begin` | The line on which the code quality violation occurred. |
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Example:
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```json
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[
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{
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"description": "'unused' is assigned a value but never used.",
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"fingerprint": "7815696ecbf1c96e6894b779456d330e",
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"location": {
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"path": "lib/index.js",
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"lines": {
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"begin": 42
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}
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}
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}
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]
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```
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NOTE: **Note:**
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Although the Code Climate spec supports more properties, those are ignored by
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GitLab.
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## Code Quality reports
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Once the Code Quality job has completed, GitLab:
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- Checks the generated report.
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- Compares the metrics between the source and target branches.
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- Shows the information right on the merge request.
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If multiple jobs in a pipeline generate a code quality artifact, only the artifact from
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the last created job (the job with the largest job ID) is used. To avoid confusion,
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configure only one job to generate a code quality artifact.
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If the Code Quality report doesn't have anything to compare to, no information
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will be displayed in the merge request area. That is the case when you add the
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Code Quality job in your `.gitlab-ci.yml` for the very first time.
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Consecutive merge requests will have something to compare to and the Code Quality
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report will be shown properly.
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<!-- ## Troubleshooting
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