debian-mirror-gitlab/doc/user/clusters/agent/gitops/helm.md

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Using Helm charts to update a Kubernetes cluster (Alpha) (FREE)

• Introduced in GitLab 15.4.
• Specifying a branch, tag, or commit reference to fetch the Kubernetes manifest files introduced in GitLab 15.7.

You can deploy Helm charts to your Kubernetes cluster and keep the resources in your cluster in sync with your charts and values. To do this, you use the pull-based GitOps features of the agent for Kubernetes.

This feature is in Alpha and an epic exists to track future work. Tell us about your use cases by leaving comments in the epic.

NOTE: This feature is Alpha. In future releases, to accommodate new features, the configuration format might change without notice.

GitOps workflow steps

To update a Kubernetes cluster by using GitOps with charts, complete the following steps.

1. Ensure you have a working Kubernetes cluster, and that the chart is in a GitLab project.
2. In the same project, register and install the GitLab agent.
3. Configure the agent configuration file so that the agent monitors the project for changes to the chart. Use the GitOps configuration reference for guidance.

Helm chart with GitOps workflow

To update a Kubernetes cluster by using Helm charts:

1. Ensure you have a working Kubernetes cluster.
2. In a GitLab project:
   • Store your Helm charts.
   • Register and install the GitLab agent.
3. Update the agent configuration file so that the agent monitors the project for changes to the chart. Use the configuration reference for guidance.

Any time you commit updates to your chart repository, the agent applies the chart in the cluster.

Helm configuration reference

The following snippet shows an example of the possible keys and values for the GitOps section of an agent configuration file (config.yaml).

gitops:
  charts:
  - release_name: my-application-release
    source:
      project:
        id: my-group/my-project-with-chart
        ref:
          branch: production
        path: dir-in-project/with/charts
    namespace: my-ns
    max_history: 1
    values:
      - inline:
          someKey: example value

Keyword	Description
charts	List of charts you want to be applied in your cluster. Charts are applied concurrently.
release_name	Required. Name of the release to use when applying the chart.
values	Optional. Custom values for the release. An array of objects. Only supports inline values.
namespace	Optional. Namespace to use when applying the chart. Defaults to default.
max_history	Optional. Maximum number of release revisions to store in the cluster.
source	Required. From where the chart should get installed. Only supports project sources.
source.project.id	Required. ID of the project where Helm chart is committed. Authentication is not supported.
source.project.ref	Optional. Git reference in the configured Git repository to fetch the Chart from. If not specified or empty, the default branch is used. If specified, it must contain either branch, tag, or commit.
source.project.ref.branch	Branch name in the configured Git repository to fetch the Chart from.
source.project.ref.tag	Tag name in the configured Git repository to fetch the Chart from.
source.project.ref.commit	Commit SHA in the configured Git repository to fetch the Chart from.
source.project.path	Optional. Path of the chart in the project repository. Root of the repository is used by default. Should be the directory with the Chart.yaml file.

Custom values

Introduced in GitLab 15.6. Requires both GitLab and the installed agent to be version 15.6 or later.

To customize the values for a release, set the values key. It must be an array of objects. Each object must have exactly one top-level key that describes where the values come from. The supported top-level keys are:

• inline: Specify the values inline in YAML format, similar to a Helm values file.

When installing a chart with custom values:

• Custom values get merged on top of the chart's default values.yaml file.
• Values from subsequent entries in the values array overwrite values from previous entries.

Example:

gitops:
  charts:
  - release_name: some-release
    values:
      - inline:
          someKey: example value
    # ...

Automatic drift remediation

Drift happens when the current configuration of an infrastructure resource differs from its desired configuration. Typically, drift is caused by manually editing resources directly, rather than by editing the code that describes the desired state. Minimizing the risk of drift helps to ensure configuration consistency and successful operations.

In GitLab, the agent for Kubernetes regularly compares the desired state from the chart source with the actual state from the Kubernetes cluster. Deviations from the desired state are fixed at every check. These checks happen automatically every 5 minutes. They are not configurable.

Example repository layout

/my-chart
 ├── templates
 |   └── ...
 ├── charts
 |   └── ...
 ├── Chart.yaml
 ├── Chart.lock
 ├── values.yaml
 ├── values.schema.json
 └── some-file-used-in-chart.txt

Known issues

The following are known issues:

• Your chart must be in a GitLab project. The project must be an agent configuration project or a public project. This known issue also exists for manifest-based GitOps and is tracked in this epic.
• Values for the chart must be in a values.yaml file. This file must be with the chart, in the same project and path.
• Because of drift detection and remediation, the release history stored in the cluster is not useful. A new release is created every five minutes and the oldest release is discarded. Eventually history consists only of the same information. View this issue for details.

Troubleshooting

Agent cannot find values for the chart

Make sure values are in values.yaml and in the same directory as the Chart.yaml file. The filename must be lowercase, with .yaml extension (not .yml).