Adding and removing Kubernetes clusters

GitLab offers integrated cluster creation for the following Kubernetes providers:

Google Kubernetes Engine (GKE).
Amazon Elastic Kubernetes Service (EKS).

GitLab can also integrate with any standard Kubernetes provider, either on-premise or hosted.

TIP: Tip: Every new Google Cloud Platform (GCP) account receives $300 in credit upon sign up, and in partnership with Google, GitLab is able to offer an additional $200 for new GCP accounts to get started with GitLab's Google Kubernetes Engine Integration. All you have to do is follow this link and apply for credit.

Before you begin

Before adding a Kubernetes cluster using GitLab, you need:

GitLab itself. Either:
- A GitLab.com account.
- A self-managed installation with GitLab version 12.5 or later. This will ensure the GitLab UI can be used for cluster creation.
The following GitLab access:
- Maintainer access to a project for a project-level cluster.
- Maintainer access to a group for a group-level cluster.
- Admin Area access for a self-managed instance-level cluster. (CORE ONLY)

Access controls

When creating a cluster in GitLab, you will be asked if you would like to create either:

A Role-based access control (RBAC) cluster.
An Attribute-based access control (ABAC) cluster.

NOTE: Note: RBAC is recommended and the GitLab default.

GitLab creates the necessary service accounts and privileges to install and run GitLab managed applications. When GitLab creates the cluster, a gitlab service account with cluster-admin privileges is created in the default namespace to manage the newly created cluster.

NOTE: Note: Restricted service account for deployment was introduced in GitLab 11.5.

When you install Helm into your cluster, the tiller service account is created with cluster-admin privileges in the gitlab-managed-apps namespace.

This service account will be:

Added to the installed Helm Tiller.
Used by Helm to install and run GitLab managed applications.

Helm will also create additional service accounts and other resources for each installed application. Consult the documentation of the Helm charts for each application for details.

If you are adding an existing Kubernetes cluster, ensure the token of the account has administrator privileges for the cluster.

The resources created by GitLab differ depending on the type of cluster.

Important notes

Note the following about access controls:

Environment-specific resources are only created if your cluster is managed by GitLab.
If your cluster was created before GitLab 12.2, it will use a single namespace for all project environments.

RBAC cluster resources

GitLab creates the following resources for RBAC clusters.

Name	Type	Details	Created when
`gitlab`	`ServiceAccount`	`default` namespace	Creating a new cluster
`gitlab-admin`	`ClusterRoleBinding`	`cluster-admin` roleRef	Creating a new cluster
`gitlab-token`	`Secret`	Token for `gitlab` ServiceAccount	Creating a new cluster
`tiller`	`ServiceAccount`	`gitlab-managed-apps` namespace	Installing Helm Tiller
`tiller-admin`	`ClusterRoleBinding`	`cluster-admin` roleRef	Installing Helm Tiller
Environment namespace	`Namespace`	Contains all environment-specific resources	Deploying to a cluster
Environment namespace	`ServiceAccount`	Uses namespace of environment	Deploying to a cluster
Environment namespace	`Secret`	Token for environment ServiceAccount	Deploying to a cluster
Environment namespace	`RoleBinding`	`edit` roleRef	Deploying to a cluster

ABAC cluster resources

GitLab creates the following resources for ABAC clusters.

Name	Type	Details	Created when
`gitlab`	`ServiceAccount`	`default` namespace	Creating a new cluster
`gitlab-token`	`Secret`	Token for `gitlab` ServiceAccount	Creating a new cluster
`tiller`	`ServiceAccount`	`gitlab-managed-apps` namespace	Installing Helm Tiller
`tiller-admin`	`ClusterRoleBinding`	`cluster-admin` roleRef	Installing Helm Tiller
Environment namespace	`Namespace`	Contains all environment-specific resources	Deploying to a cluster
Environment namespace	`ServiceAccount`	Uses namespace of environment	Deploying to a cluster
Environment namespace	`Secret`	Token for environment ServiceAccount	Deploying to a cluster

Security of GitLab Runners

GitLab Runners have the privileged mode enabled by default, which allows them to execute special commands and running Docker in Docker. This functionality is needed to run some of the Auto DevOps jobs. This implies the containers are running in privileged mode and you should, therefore, be aware of some important details.

The privileged flag gives all capabilities to the running container, which in turn can do almost everything that the host can do. Be aware of the inherent security risk associated with performing docker run operations on arbitrary images as they effectively have root access.

If you don't want to use GitLab Runner in privileged mode, either:

Use shared Runners on GitLab.com. They don't have this security issue.
Set up your own Runners using configuration described at Shared Runners. This involves:
1. Making sure that you don't have it installed via the applications.
2. Installing a Runner using docker+machine.

Create new cluster

New clusters can be created using GitLab for:

Add existing cluster

If you have an existing Kubernetes cluster, you can add it to a project, group, or instance.

For more information, see information for adding an:

Existing Kubernetes cluster, including GKE clusters.
Existing EKS cluster.

NOTE: Note: Kubernetes integration is not supported for arm64 clusters. See the issue Helm Tiller fails to install on arm64 cluster for details.

Existing Kubernetes cluster

To add a Kubernetes cluster to your project, group, or instance:

Navigate to your:
1. Project's {cloud-gear} Operations > Kubernetes page, for a project-level cluster.
2. Group's {cloud-gear} Kubernetes page, for a group-level cluster.
3. {admin} Admin Area > {cloud-gear} Kubernetes page, for an instance-level cluster.
Click Add Kubernetes cluster.
Click the Add existing cluster tab and fill in the details:
1. Kubernetes cluster name (required) - The name you wish to give the cluster.
2. Environment scope (required) - The associated environment to this cluster.
3. 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. For example, https://kubernetes.example.com rather than https://kubernetes.example.com/api/v1.
  
  Get the API URL by running this command:
```
kubectl cluster-info | grep 'Kubernetes master' | awk '/http/ {print $NF}'
```
4. CA certificate (required) - A valid Kubernetes certificate is needed to authenticate to the cluster. We will use the certificate created by default.
  1. List the secrets with kubectl get secrets, and one should be named similar to default-token-xxxxx. Copy that token name for use below.
  2. Get the certificate by running this command:
```
kubectl get secret <secret name> -o jsonpath="{['data']['ca\.crt']}" | base64 --decode
```
    NOTE: Note: If the command returns the entire certificate chain, you need copy the root ca certificate at the bottom of the chain.
5. Token - GitLab authenticates against Kubernetes using service tokens, which are scoped to a particular namespace. The token used should belong to a service account with cluster-admin privileges. To create this service account:
  1. Create a file called gitlab-admin-service-account.yaml with contents:
```
apiVersion: v1
kind: ServiceAccount
metadata:
  name: gitlab-admin
  namespace: kube-system
---
apiVersion: rbac.authorization.k8s.io/v1beta1
kind: ClusterRoleBinding
metadata:
  name: gitlab-admin
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: ClusterRole
  name: cluster-admin
subjects:
- kind: ServiceAccount
  name: gitlab-admin
  namespace: kube-system
```
  2. Apply the service account and cluster role binding to your cluster:
```
kubectl apply -f gitlab-admin-service-account.yaml
```
    You will need the container.clusterRoleBindings.create permission to create cluster-level roles. If you do not have this permission, you can alternatively enable Basic Authentication and then run the kubectl apply command as an admin:
```
kubectl apply -f gitlab-admin-service-account.yaml --username=admin --password=<password>
```
    NOTE: Note: Basic Authentication can be turned on and the password credentials can be obtained using the Google Cloud Console.
    
    Output:
```
serviceaccount "gitlab-admin" created
clusterrolebinding "gitlab-admin" created
```
  3. Retrieve the token for the gitlab-admin service account:
```
kubectl -n kube-system describe secret $(kubectl -n kube-system get secret | grep gitlab-admin | awk '{print $1}')
```
    Copy the <authentication_token> value from the output:
```
Name:         gitlab-admin-token-b5zv4
Namespace:    kube-system
Labels:       <none>
Annotations:  kubernetes.io/service-account.name=gitlab-admin
             kubernetes.io/service-account.uid=bcfe66ac-39be-11e8-97e8-026dce96b6e8

Type:  kubernetes.io/service-account-token

Data
====
ca.crt:     1025 bytes
namespace:  11 bytes
token:      <authentication_token>
```
  NOTE: Note: For GKE clusters, you will need the container.clusterRoleBindings.create permission to create a cluster role binding. You can follow the Google Cloud documentation to grant access.
6. GitLab-managed cluster - Leave this checked if you want GitLab to manage namespaces and service accounts for this cluster. See the Managed clusters section for more information.
7. Project namespace (optional) - You don't have to fill it in; by leaving it blank, GitLab will create one for you. Also:
  - 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.
Finally, click the Create Kubernetes cluster button.

After a couple of minutes, your cluster will be ready to go. You can now proceed to install some pre-defined applications.

Disable Role-Based Access Control (RBAC) (optional)

When connecting a cluster via GitLab integration, you may specify whether the cluster is RBAC-enabled or not. This will affect how GitLab interacts with the cluster for certain operations. If you did not check the "RBAC-enabled cluster" checkbox at creation time, GitLab will assume RBAC is disabled for your cluster when interacting with it. If so, you must disable RBAC on your cluster for the integration to work properly.

NOTE: Note: Disabling RBAC means that any application running in the cluster, or user who can authenticate to the cluster, has full API access. This is a security concern, and may not be desirable.

To effectively disable RBAC, global permissions can be applied granting full access:

kubectl create clusterrolebinding permissive-binding \
  --clusterrole=cluster-admin \
  --user=admin \
  --user=kubelet \
  --group=system:serviceaccounts

Enabling or disabling integration

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

Click the Enabled/Disabled switch
Hit Save for the changes to take effect

To disable the Kubernetes cluster integration, follow the same procedure.

Removing integration

To remove the Kubernetes cluster integration from your project, either:

Select Remove integration, to remove only the Kubernetes integration.
From GitLab 12.6, select Remove integration and resources, to also remove all related GitLab cluster resources (for example, namespaces, roles, and bindings) when removing the integration.

When removing the cluster integration, note:

You need Maintainer permissions and above to remove a Kubernetes cluster integration.
When you remove a cluster, you only remove its relationship to GitLab, not the cluster itself. To remove the cluster, you can do so by visiting the GKE or EKS dashboard, or using kubectl.

Learn more

To learn more on automatically deploying your applications, read about Auto DevOps.