Version 1.15. This version is no longer supported. For information about how to upgrade to version 1.16, see Upgrade clusters in the latest documentation. For more information about supported and unsupported versions, see the Version history page in the latest documentation.

Create admin clusters

In Google Distributed Cloud, you set up admin clusters to manage other clusters securely. You can create, update, upgrade, or delete user clusters from admin clusters. The user clusters run workloads separately from administration, so sensitive information is protected.

Admin clusters managing multi-cluster workloads can provide highly available (HA) reliability. In an HA cluster, if one control plane node fails, other nodes will continue to work.

An admin cluster in a multi-cluster environment provides the best fundamental security. Because access to administration data is separated from workloads, those who access user workloads have no access to sensitive administrative data, like SSH keys and service account data. As a result, there is some trade-off between security and the resources required, since a separate admin cluster means you need dedicated resources for management and workloads.

You create an admin cluster using the bmctl command. After you create an admin cluster, you create user clusters to run workloads.

Prerequisites:

Latest bmctl is downloaded (gs://anthos-baremetal-release/bmctl/1.15.11/linux-amd64/bmctl) from Cloud Storage.
Workstation running bmctl has network connectivity to all nodes in the target user clusters.
Workstation running bmctl has network connectivity to the cluster API server (control plane VIP).
SSH key used to create the Admin cluster is available to root, or there is SUDO user access on all nodes in the target admin cluster.
Connect-register service account is configured for use with Connect.

See the Google Distributed Cloud quickstart for expanded step-by-step instructions for creating a hybrid cluster. Creating an admin cluster is similar to creating a hybrid cluster, except you don't run workloads on the admin cluster.

Enable SELinux

If you want to enable SELinux to secure your containers, you must make sure that SELinux is enabled in Enforced mode on all your host machines. Starting with Google Distributed Cloud release 1.9.0 or later, you can enable or disable SELinux before or after cluster creation or cluster upgrades. SELinux is enabled by default on Red Hat Enterprise Linux (RHEL) and CentOS. If SELinux is disabled on your host machines or you aren't sure, see Securing your containers using SELinux for instructions on how to enable it.

Google Distributed Cloud supports SELinux in only RHEL and CentOS systems.

Log into gcloud CLI and create an admin cluster config file

Set the default credentials that Google Distributed Cloud can use to create the cluster with the following command:
```
gcloud auth application-default login
```
To use the automatic API enablement and service account creation features in this page, grant the Project Owner role to that principal. If the principal can't have the Project Owner role, complete the next step.
To ensure the cluster creation can succeed without granting the Project Owner role, add the following IAM roles to the principal:
- Service Account Admin
- Service Account Key Admin
- Project IAM Admin
- Compute Viewer
- Service Usage Admin
If the principal is a service account with those roles, you can run:
```
export GOOGLE_APPLICATION_CREDENTIALS=JSON_KEY_FILE
```
Replace JSON_KEY_FILE with the path to your service account's JSON key file.
Get the ID of your Google Cloud project and store it in an environment variable to use it for cluster creation:
```
export CLOUD_PROJECT_ID=$(gcloud config get-value project)
```

Create an admin cluster config with `bmctl`

After you've logged into gcloud and have your project set up, you can create the cluster config file with the bmctl command.

In the following example, all service accounts are automatically created by the bmctl create config command:

bmctl create config -c ADMIN_CLUSTER_NAME --enable-apis \
    --create-service-accounts --project-id=CLOUD_PROJECT_ID

Replace the following:

ADMIN_CLUSTER_NAME: the name of the new cluster.
CLOUD_PROJECT_ID: your Google Cloud project ID or the $CLOUD_PROJECT_ID environment variable.

Here's an example to create a config file for a admin cluster called admin1 associated with project ID my-gcp-project:

bmctl create config -c admin1 --create-service-accounts --enable-apis --project-id=my-gcp-project

The file is written to bmctl-workspace/admin1/admin1.yaml.

As an alternative to automatically enabling APIs and creating service accounts, you can also provide your existing service accounts with proper IAM permissions. This means you can skip the automatic service account creation in the previous example in the bmctl command:

bmctl create config -c admin1

Edit the cluster config file

Now that you have a cluster config file, edit it to make the following changes:

Provide the SSH private key to access the admin cluster nodes:

# bmctl configuration variables. Because this section is valid YAML but not a valid Kubernetes
# resource, this section can only be included when using bmctl to
# create the initial admin/admin cluster. Afterwards, when creating user clusters by directly
# applying the cluster and node pool resources to the existing cluster, you must remove this
# section.
gcrKeyPath: bmctl-workspace/.sa-keys/my-gcp-project-anthos-baremetal-gcr.json
sshPrivateKeyPath: /path/to/your/ssh_private_key
gkeConnectAgentServiceAccountKeyPath: bmctl-workspace/.sa-keys/my-gcp-project-anthos-baremetal-connect.json
gkeConnectRegisterServiceAccountKeyPath: bmctl-workspace/.sa-keys/my-gcp-project-anthos-baremetal-register.json
cloudOperationsServiceAccountKeyPath: bmctl-workspace/.sa-keys/my-gcp-project-anthos-baremetal-cloud-ops.json

Register your clusters to a fleet. The project ID that you specified in the bmctl create config command is automatically added to the gkeConnect.projectID field in the cluster config file. This project is referred to as the fleet host project.
- If you created your config file, using the automatic API enablement and Service Account creation features, you can skip this step.
- If you created the config file without using the automatic API enablement and Service Account creation features, reference the downloaded service account JSON keys in the corresponding gkeConnectAgentServiceAccountKeyPath and gkeConnectRegisterServiceAccountKeyPath fields of the cluster config file.

Check to make sure the config specifies a cluster type of admin (the default value):

spec:
  # Cluster type. This can be:
  #   1) admin:  to create an admin cluster. This can later be used to create user clusters.
  #   2) user:   to create a user cluster. Requires an existing admin cluster.
  #   3) hybrid: to create a hybrid cluster that runs admin cluster components and user workloads.
  #   4) standalone: to create a cluster that manages itself, runs user workloads, but does not manage other clusters.
  type: admin

Change the configuration file to specify a multi-node, high availability control plane. Specify an odd number of nodes to have a majority quorum for HA:
```
  # Control plane configuration
  controlPlane:
    nodePoolSpec:
      nodes:
      # Control plane node pools. Typically, this is either a single machine
      # or 3 machines if using a high availability deployment.
      - address: 10.200.0.4
      - address: 10.200.0.5
      - address: 10.200.0.6
```
Note: If you have an even number of nodes temporarily while ading or removing nodes for maintenance or replacement, your deployment maintains HA as long as you have enough quorum.
Specify the pod density of cluster nodes:
```
....
# NodeConfig specifies the configuration that applies to all nodes in the cluster.
nodeConfig:
  # podDensity specifies the pod density configuration.
  podDensity:
    # maxPodsPerNode specifies at most how many pods can be run on a single node.
    maxPodsPerNode: 250
....
```
For admin clusters, allowable values for maxPodsPerNode are 32-250 for HA clusters and 64-250 for non-HA clusters. The default value if unspecified is 110. Once the cluster is created, this value cannot be updated.

Pod density is also limited by your cluster's available IP resources. For details, see Pod networking.

Create the admin cluster with the cluster config

Use the bmctl command to deploy the cluster:

bmctl create cluster -c ADMIN_CLUSTER_NAME

ADMIN_CLUSTER_NAME specifies the cluster name created in the previous section.

The following shows an example of the command to create a cluster called admin1:

bmctl create cluster -c admin1

Sample admin cluster configurations

For example admin cluster configurations, see Admin clusters in the Cluster configuration samples.