# Connecting GitLab with a Kubernetes cluster

> [Introduced](https://gitlab.com/gitlab-org/gitlab-ce/issues/35954) in GitLab 10.1.

Connect your project to Google Kubernetes Engine (GKE) or an existing Kubernetes
cluster in a few steps.

With a cluster associated to your project, you can use Review Apps, deploy your
applications, run your pipelines, and much more, in an easy way.

There are two options when adding a new cluster to your project; either associate
your account with Google Kubernetes Engine (GKE) so that you can [create new
clusters](#adding-and-creating-a-new-gke-cluster-via-gitlab) from within GitLab,
or provide the credentials to an [existing Kubernetes cluster](#adding-an-existing-kubernetes-cluster).

## Prerequisites

In order to be able to manage your Kubernetes cluster through GitLab, the
following prerequisites must be met.

**For a cluster hosted on GKE:**

- The [Google authentication integration](../../../integration/google.md) must
  be enabled in GitLab at the instance level. If that's not the case, ask your
  GitLab administrator to enable it.
- Your associated Google account must have the right privileges to manage
  clusters on GKE. That would mean that a [billing
  account](https://cloud.google.com/billing/docs/how-to/manage-billing-account)
  must be set up and that you have to have permissions to access it.
- You must have Master [permissions] in order to be able to access the
  **Cluster** page.
- You must have [Cloud Billing API](https://cloud.google.com/billing/) enabled
- You must have [Resource Manager
  API](https://cloud.google.com/resource-manager/)

**For an existing Kubernetes cluster:**

- Since the cluster is already created, there are no prerequisites.

---

If all of the above requirements are met, you can proceed to add a new Kubernetes
cluster.

## Adding and creating a new GKE cluster via GitLab

NOTE: **Note:**
You need Master [permissions] and above to access the Clusters page.

Before proceeding, make sure all [prerequisites](#prerequisites) are met.
To add a new cluster hosted on GKE to your project:

1. Navigate to your project's **CI/CD > Clusters** page.
1. Click on **Add cluster**.
1. Click on **Create with GKE**.
1. Connect your Google account if you haven't done already by clicking the
   **Sign in with Google** button.
1. Fill in the requested values:
  - **Cluster name** (required) - The name you wish to give the cluster.
  - **GCP project ID** (required) - The ID of the project you created in your GCP
    console that will host the Kubernetes cluster. This must **not** be confused
    with the project name. Learn more about [Google Cloud Platform projects](https://cloud.google.com/resource-manager/docs/creating-managing-projects).
  - **Zone** - The [zone](https://cloud.google.com/compute/docs/regions-zones/)
    under which the cluster will be created.
  - **Number of nodes** - The number of nodes you wish the cluster to have.
  - **Machine type** - The [machine type](https://cloud.google.com/compute/docs/machine-types)
    of the Virtual Machine instance that the cluster will be based on.
  - **Environment scope** - The [associated environment](#setting-the-environment-scope) to this cluster.
1. Finally, click the **Create cluster** button.

After a few moments, your cluster should be created. If something goes wrong,
you will be notified.

You can now proceed to install some pre-defined applications and then
enable the Cluster integration.

## Adding an existing Kubernetes cluster

NOTE: **Note:**
You need Master [permissions] and above to access the Clusters page.

To add an existing Kubernetes cluster to your project:

1. Navigate to your project's **CI/CD > Clusters** page.
1. Click on **Add cluster**.
1. Click on **Add an existing cluster** and fill in the details:
    - **Cluster name** (required) - The name you wish to give the cluster.
    - **Environment scope** (required)- The
      [associated environment](#setting-the-environment-scope) to this cluster.
    - **API URL** (required) -
      It's the URL that GitLab uses to access the Kubernetes API. Kubernetes
      exposes several APIs, we want the "base" URL that is common to all of them,
      e.g., `https://kubernetes.example.com` rather than `https://kubernetes.example.com/api/v1`.
    - **CA certificate** (optional) -
      If the API is using a self-signed TLS certificate, you'll also need to include
      the `ca.crt` contents here.
    - **Token** -
      GitLab authenticates against Kubernetes using service tokens, which are
      scoped to a particular `namespace`. If you don't have a service token yet,
      you can follow the
      [Kubernetes documentation](https://kubernetes.io/docs/tasks/configure-pod-container/configure-service-account/)
      to create one. You can also view or create service tokens in the
      [Kubernetes dashboard](https://kubernetes.io/docs/tasks/access-application-cluster/web-ui-dashboard/#config)
      (under **Config > Secrets**).
    - **Project namespace** (optional) - The following apply:
      - By default you don't have to fill it in; by leaving it blank, GitLab will
        create one for you.
      - Each project should have a unique namespace.
      - The project namespace is not necessarily the namespace of the secret, if
        you're using a secret with broader permissions, like the secret from `default`.
      - You should **not** use `default` as the project namespace.
      - If you or someone created a secret specifically for the project, usually
        with limited permissions, the secret's namespace and project namespace may
        be the same.
1. Finally, click the **Create cluster** button.

The Kubernetes service takes the following parameters:

After a few moments, your cluster should be created. If something goes wrong,
you will be notified.

You can now proceed to install some pre-defined applications and then
enable the Cluster integration.

## Installing applications

GitLab provides a one-click install for various applications which will be
added directly to your configured cluster. Those applications are needed for
[Review Apps](../../../ci/review_apps/index.md) and [deployments](../../../ci/environments.md).

| Application | GitLab version | Description |
| ----------- | :------------: | ----------- |
| [Helm Tiller](https://docs.helm.sh/) | 10.2+ | Helm is a package manager for Kubernetes and is required to install all the other applications. It will be automatically installed as a dependency when you try to install a different app. It is installed in its own pod inside the cluster which can run the `helm` CLI in a safe environment. |
| [Ingress](https://kubernetes.io/docs/concepts/services-networking/ingress/) | 10.2+ | Ingress can provide load balancing, SSL termination, and name-based virtual hosting. It acts as a web proxy for your applications and is useful if you want to use [Auto DevOps](../../../topics/autodevops/index.md) or deploy your own web apps. |
| [Prometheus](https://prometheus.io/docs/introduction/overview/) | 10.4+ | Prometheus is an open-source monitoring and alerting system useful to supervise your deployed applications |

## Setting the environment scope

When adding more than one clusters, you need to differentiate them with an
environment scope. The environment scope associates clusters and
[environments](../../../ci/environments.md) in an 1:1 relationship similar to how the
[environment-specific variables](../../../ci/variables/README.md#limiting-environment-scopes-of-secret-variables)
work.

The default environment scope is `*`, which means all jobs, regardless of their
environment, will use that cluster. Each scope can only be used by a single
cluster in a project, and a validation error will occur if otherwise.

---

For example, let's say the following clusters exist in a project:

| Cluster    | Environment scope   |
| ---------- | ------------------- |
| Development| `*`                 |
| Staging    | `staging/*`         |
| Production | `production/*`      |

And the following environments are set in [`.gitlab-ci.yml`](../../../ci/yaml/README.md):

```yaml
stages:
- test
- deploy

test:
  stage: test
  script: sh test

deploy to staging:
  stage: deploy
  script: make deploy
  environment:
    name: staging/$CI_COMMIT_REF_NAME
    url: https://staging.example.com/

deploy to production:
  stage: deploy
  script: make deploy
  environment:
    name: production/$CI_COMMIT_REF_NAME
    url: https://example.com/
```

The result will then be:

- The development cluster will be used for the "test" job.
- The staging cluster will be used for the "deploy to staging" job.
- The production cluster will be used for the "deploy to production" job.

## Multiple Kubernetes clusters

> Introduced in [GitLab Enterprise Edition Premium][ee] 10.3.

With GitLab EEP, you can associate more than one Kubernetes clusters to your
project. That way you can have different clusters for different environments,
like dev, staging, production, etc.

To add another cluster, follow the same steps as described in [adding a
Kubernetes cluster](#adding-a-kubernetes-cluster) and make sure to
[set an environment scope](#setting-the-environment-scope) that will
differentiate the new cluster with the rest.

## Deployment variables

The Kubernetes cluster integration exposes the following
[deployment variables](../../../ci/variables/README.md#deployment-variables) in the
GitLab CI/CD build environment:

- `KUBE_URL` - Equal to the API URL.
- `KUBE_TOKEN` - The Kubernetes token.
- `KUBE_NAMESPACE` - The Kubernetes namespace is auto-generated if not specified.
  The default value is `<project_name>-<project_id>`. You can overwrite it to
  use different one if needed, otherwise the `KUBE_NAMESPACE` variable will
  receive the default value.
- `KUBE_CA_PEM_FILE` - Only present if a custom CA bundle was specified. Path
  to a file containing PEM data.
- `KUBE_CA_PEM` (deprecated) - Only if a custom CA bundle was specified. Raw PEM data.
- `KUBECONFIG` - Path to a file containing `kubeconfig` for this deployment.
  CA bundle would be embedded if specified.

## Enabling or disabling the Cluster integration

After you have successfully added your cluster information, you can enable the
Cluster integration:

1. Click the "Enabled/Disabled" switch
1. Hit **Save** for the changes to take effect

You can now start using your Kubernetes cluster for your deployments.

To disable the Cluster integration, follow the same procedure.

## Removing the Cluster integration

NOTE: **Note:**
You need Master [permissions] and above to remove a cluster integration.

NOTE: **Note:**
When you remove a cluster, you only remove its relation to GitLab, not the
cluster itself. To remove the cluster, you can do so by visiting the GKE
dashboard or using `kubectl`.

To remove the Cluster integration from your project, simply click on the
**Remove integration** button. You will then be able to follow the procedure
and [add a cluster](#adding-a-cluster) again.

## What you can get with the Kubernetes integration

Here's what you can do with GitLab if you enable the Kubernetes integration.

### Deploy Boards (EEP)

> Available in [GitLab Enterprise Edition Premium][ee].

GitLab's Deploy Boards offer a consolidated view of the current health and
status of each CI [environment](../../../ci/environments.md) running on Kubernetes,
displaying the status of the pods in the deployment. Developers and other
teammates can view the progress and status of a rollout, pod by pod, in the
workflow they already use without any need to access Kubernetes.

[> Read more about Deploy Boards](https://docs.gitlab.com/ee/user/project/deploy_boards.html)

### Canary Deployments (EEP)

> Available in [GitLab Enterprise Edition Premium][ee].

Leverage [Kubernetes' Canary deployments](https://kubernetes.io/docs/concepts/cluster-administration/manage-deployment/#canary-deployments)
and visualize your canary deployments right inside the Deploy Board, without
the need to leave GitLab.

[> Read more about Canary Deployments](https://docs.gitlab.com/ee/user/project/canary_deployments.html)

### Kubernetes monitoring

Automatically detect and monitor Kubernetes metrics. Automatic monitoring of
[NGINX ingress](../integrations/prometheus_library/nginx.md) is also supported.

[> Read more about Kubernetes monitoring](../integrations/prometheus_library/kubernetes.md)

### Auto DevOps

Auto DevOps automatically detects, builds, tests, deploys, and monitors your
applications.

To make full use of Auto DevOps(Auto Deploy, Auto Review Apps, and Auto Monitoring)
you will need the Kubernetes project integration enabled.

[> Read more about Auto DevOps](../../../topics/autodevops/index.md)

### Web terminals

NOTE: **Note:**
Introduced in GitLab 8.15. You must be the project owner or have `master` permissions
to use terminals. Support is limited to the first container in the
first pod of your environment.

When enabled, the Kubernetes service adds [web terminal](../../../ci/environments.md#web-terminals)
support to your [environments](../../../ci/environments.md). This is based on the `exec` functionality found in
Docker and Kubernetes, so you get a new shell session within your existing
containers. To use this integration, you should deploy to Kubernetes using
the deployment variables above, ensuring any pods you create are labelled with
`app=$CI_ENVIRONMENT_SLUG`. GitLab will do the rest!

[permissions]: ../../permissions.md
[ee]: https://about.gitlab.com/gitlab-ee/