Code Quality

DETAILS: Tier: Free, Premium, Ultimate Offering: GitLab.com, Self-managed, GitLab Dedicated

Use Code Quality to analyze your source code's quality and complexity. This helps keep your project's code simple, readable, and easier to maintain. Code Quality should supplement your other review processes, not replace them.

Code Quality runs in CI/CD pipelines, and helps you avoid merging changes that would degrade your code's quality.

Code Quality uses the open source Code Climate tool, and selected plugins, to analyze your source code. To confirm if your code's languages are covered, see the Code Climate list of Supported Languages for Maintainability. You can extend the code coverage either by using Code Climate Analysis Plugins or a custom tool.

Features per tier

Different features are available in different GitLab tiers, as shown in the following table:

View Code Quality results

Code Quality results are shown in the:

• Merge request widget
• Merge request changes view
• Pipeline details view
• Project quality view

Merge request widget

Code Quality analysis results display in the merge request widget area if a report from the target branch is available for comparison. The merge request widget displays Code Quality findings and resolutions that were introduced by the changes made in the merge request. Multiple Code Quality findings with identical fingerprints display as a single entry in the merge request widget. Each individual finding is available in the full report available in the Pipeline details view.

Merge request changes view

DETAILS: Tier: Ultimate Offering: GitLab.com, Self-managed, GitLab Dedicated

Code Quality results display in the merge request Changes view. Lines containing Code Quality issues are marked by a symbol beside the gutter. Select the symbol to see the list of issues, then select an issue to see its details.

Pipeline details view

DETAILS: Tier: Premium, Ultimate Offering: GitLab.com, Self-managed, GitLab Dedicated

The full list of Code Quality violations generated by a pipeline is shown in the Code Quality tab of the pipeline's details page. The pipeline details view displays all Code Quality findings that were found on the branch it was run on.

Project quality view

DETAILS: Tier: Ultimate Offering: GitLab.com, Self-managed

The project quality view displays an overview of the code quality findings. The view can be found under Analyze > CI/CD analytics, and requires project_quality_summary_page feature flag to be enabled for this particular project.

Enable Code Quality

Prerequisites:

• GitLab CI/CD configuration (.gitlab-ci.yml) must include the test stage.
• If you're using instance runners, the Code Quality job must be configured for the Docker-in-Docker workflow. When using this workflow, the /builds volume must be mapped to allow reports to be saved.
• If you're using private runners, you should use an alternative configuration recommended for running Code Quality analysis more efficiently.
• The runner must have enough disk space to store the generated Code Quality files. For example, on the GitLab project the files are approximately 7 GB.

To enable Code Quality, either:

• Enable Auto DevOps, which includes Auto Code Quality.

• Include the Code Quality template in your .gitlab-ci.yml file.

  Example:

     include:
     - template: Jobs/Code-Quality.gitlab-ci.yml

  Code Quality now runs in pipelines.

WARNING: On self-managed instances, if a malicious actor compromises the Code Quality job definition they could execute privileged Docker commands on the runner host. Having proper access control policies mitigates this attack vector by allowing access only to trusted actors.

Improve Code Quality performance with private runners

If you have private runners, you should use this configuration for improved performance of Code Quality because:

• Privileged mode is not used.
• Docker-in-Docker is not used.
• Docker images, including all CodeClimate images, are cached, and not re-fetched for subsequent jobs.

This alternative configuration uses socket binding to share the Runner's Docker daemon with the job environment. Before implementing this configuration, consider its limitations.

To use private runners:

1. Register a new runner:

   $ gitlab-runner register --executor "docker" \
     --docker-image="docker:latest" \
     --url "https://gitlab.com/" \
     --description "cq-sans-dind" \
     --tag-list "cq-sans-dind" \
     --locked="false" \
     --access-level="not_protected" \
     --docker-volumes "/cache"\
     --docker-volumes "/builds:/builds"\
     --docker-volumes "/var/run/docker.sock:/var/run/docker.sock" \
     --registration-token="<project_token>" \
     --non-interactive

2. Optional, but recommended: Set the builds directory to /tmp/builds, so job artifacts are periodically purged from the runner host. If you skip this step, you must clean up the default builds directory (/builds) yourself. You can do this by adding the following two flags to gitlab-runner register in the previous step.

   --builds-dir "/tmp/builds"
   --docker-volumes "/tmp/builds:/tmp/builds" # Use this instead of --docker-volumes "/builds:/builds"

   The resulting configuration:

   [[runners]]
     name = "cq-sans-dind"
     url = "https://gitlab.com/"
     token = "<project_token>"
     executor = "docker"
     builds_dir = "/tmp/builds"
     [runners.docker]
       tls_verify = false
       image = "docker:latest"
       privileged = false
       disable_entrypoint_overwrite = false
       oom_kill_disable = false
       disable_cache = false
       volumes = ["/cache", "/var/run/docker.sock:/var/run/docker.sock", "/tmp/builds:/tmp/builds"]
       shm_size = 0
     [runners.cache]
       [runners.cache.s3]
       [runners.cache.gcs]

3. Apply two overrides to the code_quality job created by the template:

   include:
     - template: Jobs/Code-Quality.gitlab-ci.yml
   
   code_quality:
     services:            # Shut off Docker-in-Docker
     tags:
       - cq-sans-dind     # Set this job to only run on our new specialized runner

Code Quality now runs in standard Docker mode.

Run Code Quality rootless with private runners

If you are using private runners and would like to run the Code Quality scans in rootless Docker mode code quality requires some special changes to allow it to run properly. This may require having a runner dedicated to running only code quality jobs because changes in socket binding may cause problems in other jobs.

To use a rootless private runner:

1. Register a new runner:

   Replace /run/user/<gitlab-runner-user>/docker.sock with the path to the local docker.sock for the gitlab-runner user.

   $ gitlab-runner register --executor "docker" \
     --docker-image="docker:latest" \
     --url "https://gitlab.com/" \
     --description "cq-rootless" \
     --tag-list "cq-rootless" \
     --locked="false" \
     --access-level="not_protected" \
     --docker-volumes "/cache" \
     --docker-volumes "/tmp/builds:/tmp/builds" \
     --docker-volumes "/run/user/<gitlab-runner-user>/docker.sock:/run/user/<gitlab-runner-user>/docker.sock" \
     --token "<project_token>" \
     --non-interactive \
     --builds-dir "/tmp/builds" \
     --env "DOCKER_HOST=unix:///run/user/<gitlab-runner-user>/docker.sock" \
     --docker-host "unix:///run/user/<gitlab-runner-user>/docker.sock"

   The resulting configuration:

   [[runners]]
     name = "cq-rootless"
     url = "https://gitlab.com/"
     token = "<project_token>"
     executor = "docker"
     builds_dir = "/tmp/builds"
     environment = ["DOCKER_HOST=unix:///run/user/<gitlab-runner-user>/docker.sock"]
     [runners.docker]
       tls_verify = false
       image = "docker:latest"
       privileged = false
       disable_entrypoint_overwrite = false
       oom_kill_disable = false
       disable_cache = false
       volumes = ["/cache", "/run/user/<gitlab-runner-user>/docker.sock:/run/user/<gitlab-runner-user>/docker.sock", "/tmp/builds:/tmp/builds"]
       shm_size = 0
       host = "unix:///run/user/<gitlab-runner-user>/docker.sock"
     [runners.cache]
       [runners.cache.s3]
       [runners.cache.gcs]

2. Apply the following overrides to the code_quality job created by the template:

   code_quality:
     services:
     variables:
       DOCKER_SOCKET_PATH: /run/user/997/docker.sock
     tags:
       - cq-rootless

Code Quality now runs in standard Docker mode and rootless.

The same configuration is required if your goal is to use rootless Podman to run Docker with code quality. Make sure to replace /run/user/<gitlab-runner-user>/docker.sock with the correct podman.sock path in your system, for example: /run/user/<gitlab-runner-user>/podman/podman.sock.

Disable Code Quality

The code_quality job doesn't run if the $CODE_QUALITY_DISABLED CI/CD variable is present. For more information about how to define a variable, see GitLab CI/CD variables.

To disable Code Quality, create a custom CI/CD variable named CODE_QUALITY_DISABLED, for either:

• The whole project.
• A single pipeline.

Customizing scan settings

The Code Quality scan settings can be changed using CI/CD variables in .gitlab-ci.yml.

To configure the Code Quality job:

1. Declare a job with the same name as the Code Quality job, after the template's inclusion.
2. Specify additional keys in the job's stanza.

For an example, see Download output in HTML format.

Available CI/CD variables

Code Quality can be customized by defining available CI/CD variables:

Output

Code Quality outputs a report containing details of issues found. The content of this report is processed internally and the results shown in the UI. The report is also output as a job artifact of the code_quality job, named gl-code-quality-report.json. You can optionally output the report in HTML format. For example, you could publish the HTML format file on GitLab Pages for even easier reviewing.

Output in JSON and HTML format

To output the Code Quality report in JSON and HTML format, you create an additional job. This requires Code Quality to be run twice, once each for file format.

To output the Code Quality report in HTML format, add another job to your template by using extends: code_quality:

include:
  - template: Jobs/Code-Quality.gitlab-ci.yml

code_quality_html:
  extends: code_quality
  variables:
    REPORT_FORMAT: html
  artifacts:
    paths: [gl-code-quality-report.html]

Both the JSON and HTML files are output as job artifacts. The HTML file is contained in the artifacts.zip job artifact.

Output in only HTML format

To download the Code Quality report in only HTML format, set REPORT_FORMAT to html, overriding the default definition of the code_quality job.

NOTE: This does not create a JSON format file, so Code Quality results are not shown in the merge request widget, pipeline report, or changes view.

include:
  - template: Jobs/Code-Quality.gitlab-ci.yml

code_quality:
  variables:
    REPORT_FORMAT: html
  artifacts:
    paths: [gl-code-quality-report.html]

The HTML file is output as a job artifact.

Use Code Quality with merge request pipelines

The default Code Quality configuration does not allow the code_quality job to run on merge request pipelines.

To enable Code Quality to run on merge request pipelines, overwrite the code quality rules, or workflow: rules, so that they match your current rules.

For example:

include:
  - template: Jobs/Code-Quality.gitlab-ci.yml

code_quality:
  rules:
    - if: $CODE_QUALITY_DISABLED
      when: never
    - if: $CI_PIPELINE_SOURCE == "merge_request_event" # Run code quality job in merge request pipelines
    - if: $CI_COMMIT_BRANCH == $CI_DEFAULT_BRANCH      # Run code quality job in pipelines on the default branch (but not in other branch pipelines)
    - if: $CI_COMMIT_TAG                               # Run code quality job in pipelines for tags

Use a private container image registry

Using a private container image registry can reduce the time taken to download images, and also reduce external dependencies. You must configure the registry prefix to be passed down to CodeClimate's subsequent docker pull commands for individual engines, because of the nested method of container execution.

The following variables can address all of the required image pulls:

• CODE_QUALITY_IMAGE: A fully prefixed image name that can be located anywhere accessible from your job environment. GitLab container registry can be used here to host your own copy.
• CODECLIMATE_PREFIX: The domain of your intended container image registry. This is a configuration option supported by CodeClimate CLI. You must:
  • Include a trailing slash (/).
  • Not include a protocol prefix, such as https://.
• CODECLIMATE_REGISTRY_USERNAME: An optional variable to specify the username for the registry domain parsed from CODECLIMATE_PREFIX.
• CODECLIMATE_REGISTRY_PASSWORD: An optional variable to specify the password for the registry domain parsed from CODECLIMATE_PREFIX.

include:
  - template: Jobs/Code-Quality.gitlab-ci.yml

code_quality:
  variables:
    CODE_QUALITY_IMAGE: "my-private-registry.local:12345/codequality:0.85.24"
    CODECLIMATE_PREFIX: "my-private-registry.local:12345/"

This example is specific to GitLab Code Quality. For more general instructions on how to configure DinD with a registry mirror, see Enable registry mirror for Docker-in-Docker service.

Required images

The following images are required for the default .codeclimate.yml:

• codeclimate/codeclimate-structure:latest
• codeclimate/codeclimate-csslint:latest
• codeclimate/codeclimate-coffeelint:latest
• codeclimate/codeclimate-duplication:latest
• codeclimate/codeclimate-eslint:latest
• codeclimate/codeclimate-fixme:latest
• codeclimate/codeclimate-rubocop:rubocop-0-92

If you are using a custom .codeclimate.yml configuration file, you must add the specified plugins in your private container registry.

Use DockerHub with authentication

You can use DockerHub as an alternate source of the Code Quality images.

Prerequisites:

• Add the username and password as protected CI/CD variables in the project.

To use DockerHub, configure the following variables in the .gitlab-ci.yml file:

• CODECLIMATE_PREFIX
• CODECLIMATE_REGISTRY_USERNAME
• CODECLIMATE_REGISTRY_PASSWORD

Example:

include:
  - template: Jobs/Code-Quality.gitlab-ci.yml

code_quality:
  variables:
    CODECLIMATE_PREFIX: "registry-1.docker.io/"
    CODECLIMATE_REGISTRY_USERNAME: $DOCKERHUB_USERNAME
    CODECLIMATE_REGISTRY_PASSWORD: $DOCKERHUB_PASSWORD

Use the Dependency Proxy

You can use a Dependency Proxy to reduce the time taken to download dependencies.

Prerequisites:

• Dependency Proxy enabled in the project's group.

To reference the Dependency Proxy, configure the following variables in the .gitlab-ci.yml file:

• CODE_QUALITY_IMAGE
• CODECLIMATE_PREFIX
• CODECLIMATE_REGISTRY_USERNAME
• CODECLIMATE_REGISTRY_PASSWORD

For example:

include:
  - template: Jobs/Code-Quality.gitlab-ci.yml

code_quality:
  variables:
    ## You must add a trailing slash to `$CI_DEPENDENCY_PROXY_GROUP_IMAGE_PREFIX`.
    CODECLIMATE_PREFIX: $CI_DEPENDENCY_PROXY_GROUP_IMAGE_PREFIX/
    CODECLIMATE_REGISTRY_USERNAME: $CI_DEPENDENCY_PROXY_USER
    CODECLIMATE_REGISTRY_PASSWORD: $CI_DEPENDENCY_PROXY_PASSWORD

Implement a custom tool

You can integrate a custom tool into GitLab to provide Code Quality reports.

The Code Quality report artifact JSON file must contain an array of objects with the following properties:

NOTE: Although the Code Climate specification supports more properties, those are ignored by GitLab. The GitLab parser does not allow a byte order mark at the beginning of the file.

To implement a custom Code Quality tool:

1. Define a job in your .gitlab-ci.yml file that generates the Code Quality report artifact.
2. Configure the tool to generate the Code Quality report artifact as a JSON file that implements a subset of the Code Climate spec.

Example:

[
  {
    "description": "'unused' is assigned a value but never used.",
    "check_name": "no-unused-vars",
    "fingerprint": "7815696ecbf1c96e6894b779456d330e",
    "severity": "minor",
    "location": {
      "path": "lib/index.js",
      "lines": {
        "begin": 42
      }
    }
  }
]

Integrate multiple tools

Code Quality combines the results from all jobs in a pipeline into a single gl-code-quality-report.json file. As a result, multiple individual tools can be used in a pipeline, either alongside, or in place of, the supported Code-Quality.gitlab-ci.yml template.

Here is an example that returns ESLint output in the necessary format:

eslint:
  image: node:18-alpine
  script:
    - npm ci
    - npx eslint --format gitlab .
  artifacts:
    reports:
      codequality: gl-code-quality-report.json

Using Analysis Plugins

Code Quality functionality can be extended by using Code Climate Analysis Plugins.

For example, to use the SonarJava analyzer:

1. Add a file named .codeclimate.yml to the root of your repository

2. Add the enablement code for the plugin to the root of your repository to the .codeclimate.yml file:

   version: "2"
   plugins:
     sonar-java:
       enabled: true

This adds SonarJava to the plugins: section of the default .codeclimate.yml included in your project.

Changes to the plugins: section do not affect the exclude_patterns section of the default .codeclimate.yml. See the Code Climate documentation on excluding files and folders for more details.

Using Code Quality in Kubernetes and OpenShift

You must set up Docker in a Docker container (Docker-in-Docker) to use Code Quality. The Kubernetes executor supports Docker-in-Docker.

To ensure Code Quality jobs can run on a Kubernetes executor:

• If you're using TLS to communicate with the Docker daemon, the executor must be running in privileged mode. Additionally, the certificate directory must be specified as a volume mount.
• It is possible that the DinD service doesn't start up fully before the Code Quality job starts. This is a limitation documented in Troubleshooting the Kubernetes executor. To resolve the issue, use before_script to wait for the Docker daemon to fully boot up. For an example, see the configuration in the .gitlab-ci.yml file below.

Kubernetes

To run Code Quality in Kubernetes:

• The Docker in Docker service must be added as a service container in the config.toml file.
• The Docker daemon in the service container must listen on a TCP and UNIX socket, as both sockets are required by Code Quality.
• The Docker socket must be shared with a volume.

Due to a Docker requirement, the privileged flag must be enabled for the service container.

[runners.kubernetes]

[runners.kubernetes.service_container_security_context]
privileged = true
allow_privilege_escalation = true

[runners.kubernetes.volumes]

[[runners.kubernetes.volumes.empty_dir]]
mount_path = "/var/run/"
name = "docker-sock"

[[runners.kubernetes.services]]
alias = "dind"
command = [
    "--host=tcp://0.0.0.0:2375",
    "--host=unix://var/run/docker.sock",
    "--storage-driver=overlay2"
]
entrypoint = ["dockerd"]
name = "docker:20.10.12-dind"

NOTE: If you use the GitLab Runner Helm Chart, you can use the above Kubernetes configuration in the config field in the values.yaml file.

To ensure that you use the overlay2 storage driver, which offers the best overall performance:

• Specify the DOCKER_HOST that the Docker CLI communicates with.
• Set the DOCKER_DRIVER variable to empty.

Use the before_script section to wait for the Docker daemon to fully boot up. Since GitLab Runner v16.9, this can also be done by just setting the HEALTHCHECK_TCP_PORT variable.

include:
  - template: Code-Quality.gitlab-ci.yml

code_quality:
  services: []
  variables:
    DOCKER_HOST: tcp://dind:2375
    DOCKER_DRIVER: ""
  before_script:
    - while ! docker info > /dev/null 2>&1; do sleep 1; done

OpenShift

For OpenShift, you should use the GitLab Runner Operator. To give the Docker daemon in the service container permissions to initialize its storage, you must mount the /var/lib directory as a volume mount.

NOTE: If you cannot to mount the /var/lib directory as a volume mount, you can set --storage-driver to vfs instead. If you opt for the vfs value, it might have a negative impact on performance.

To configure permissions for the Docker daemon,

1. Create a file called config.toml with the configuration provided below. This configuration will be used to customized GitLab Runner generated config.toml:

[[runners]]

[runners.kubernetes]

[runners.kubernetes.service_container_security_context]
privileged = true
allow_privilege_escalation = true

[runners.kubernetes.volumes]

[[runners.kubernetes.volumes.empty_dir]]
mount_path = "/var/run/"
name = "docker-sock"

[[runners.kubernetes.volumes.empty_dir]]
mount_path = "/var/lib/"
name = "docker-data"

[[runners.kubernetes.services]]
alias = "dind"
command = [
    "--host=tcp://0.0.0.0:2375",
    "--host=unix://var/run/docker.sock",
    "--storage-driver=overlay2"
]
entrypoint = ["dockerd"]
name = "docker:20.10.12-dind"

1. Set the custom configuration to your runner.

2. Optional. Attach a privileged service account to the build Pod. This depends on your OpenShift cluster setup:

   oc create sa dind-sa
   oc adm policy add-scc-to-user anyuid -z dind-sa
   oc adm policy add-scc-to-user -z dind-sa privileged

3. Set the permissions in the [runners.kubernetes] section.

4. Set the job definition stays the same as in Kubernetes case:

   include:
   - template: Code-Quality.gitlab-ci.yml
   
   code_quality:
   services: []
   variables:
     DOCKER_HOST: tcp://dind:2375
     DOCKER_DRIVER: ""
   before_script:
     - while ! docker info > /dev/null 2>&1; do sleep 1; done

Volumes and Docker storage

Docker stores all of its data in the /var/lib volume, which could result in a large volume. To reuse Docker-in-Docker storage across the cluster, you can use Persistent Volumes as an alternative.