Installation overview: choosing a deployment model

Anthos on bare metal supports multiple deployment models to meet different availability, isolation, and resource footprint needs. This page defines the concepts all deployment models share, and describes each deployment model.

User clusters

A user cluster is a Kubernetes cluster that runs your containerized workloads. It consists of control plane nodes and worker nodes. Anthos on bare metal supports one or more user clusters. User clusters must contain one or more worker nodes that run user workloads.

Admin clusters

An admin cluster is a Kubernetes cluster that manages one or more user clusters. Your admin cluster can perform the following tasks:

  • Create user clusters
  • Upgrade user clusters
  • Update user clusters
  • Delete user clusters

To create a user cluster, your admin cluster sets up the Anthos on bare metal components on the user cluster's control plane and worker nodes. Your admin cluster only have control plane nodes because the Anthos on bare metal components run on the control plane nodes.

Your admin cluster contains the following types of sensitive data:

  • SSH credentials: Used to enable remote installation
  • Google Cloud service account keys: Used to access features like Container Registry

To protect the sensitive data, restrict access to your admin cluster.

High availability

You can run admin or user clusters in high availability (HA) mode. This mode requires three or more control plane nodes running in your cluster. If you run a cluster in non-HA mode, your cluster requires only one control plane node. To avoid having a single point of failure, use the HA mode for production deployments. Use the non-HA mode for non-mission critical environments, for example a testing environment, where you can re-create the cluster if the single control plane node fails. An HA user cluster must have two or more worker nodes in case a worker node fails.

Deployment models

Anthos on bare metal supports the following deployment models to meet different requirements:

  • Standalone cluster deployment
  • Multi-cluster deployment
  • Hybrid cluster deployment

Standalone cluster deployment

This deployment model has a single cluster that serves as a user cluster and as an admin cluster.

This model has the following advantages:

  • It doesn't require a separate admin cluster
  • Saves three nodes in an HA setup.

This model has the following security tradeoffs because workloads run on a cluster with the following sensitive data:

  • SSH credentials
  • Google Cloud service account keys

Use this model if you meet any of the following conditions:

  • You manage every cluster independently.
  • You have a small number of worker nodes.
  • You support a single team.
  • You run a single workload type.

This model works well in the following situations:

  • Every cluster is independently managed with different SSH keys and Google Cloud credentials
  • Clusters run in network isolated partitions like demilitarized zones (DMZs)
  • Clusters run in edge locations

Footprint

A standalone cluster deployment requires the following nodes:

  • Control plane nodes:

    • One control plane node for non-HA
    • Three or more control plane nodes for HA
  • Worker nodes:

    • One or more worker nodes for non-HA
    • Two or more worker nodes for HA

Multi-cluster deployment

Use this deployment model if you have a fleet of clusters in the same datacenter that you want to manage from a centralized place, and for larger deployments that need isolation between different teams or between development and production workloads.

This deployment model consists of the following clusters:

  • One admin cluster: The central management point that provides an API to manage user clusters. Your admin cluster only runs management components.
  • One or more user clusters: Contain the control plane nodes and the worker nodes, which run user workloads.

This model meets the following requirements:

  • Provides a centralized control plane and API to manage your user clusters' lifecycles.
  • Provides isolation between different teams.
  • Provides isolation between development and production workloads.
  • You don't have to share SSH credentials and service account keys with cluster owners.
  • You can integrate your deployment with your own control planes

Footprint

A multi-cluster deployment requires the following nodes:

  • Admin cluster

    • One control plane node for non-HA
    • Three or more control plane nodes for HA
  • User clusters - You can configure HA for each user cluster independently.

    • Control plane nodes:

      • One control plane node for non-HA
      • Three or more control plane nodes for HA
    • Worker nodes:

      • One or more worker nodes for non-HA
      • Two or more worker nodes for HA

Hybrid cluster deployment

This deployment model is a specialized multi-cluster deployment. Use this model to run user workloads on your admin cluster. Your admin cluster still manages additional user clusters. You can create a hybrid cluster deployment from a standalone cluster deployment by adding more user clusters to support multiple teams or workload types.

This model meets the following requirements:

  • Allows re-use of control plane nodes for user workloads.
  • There are no security concerns regarding running user workloads on your admin cluster, which contains sensitive data.

Footprint

A hybrid cluster deployment requires the following nodes:

  • Hybrid cluster

    • Control plane nodes:

      • One control plane node for non-HA
      • Three or more control plane nodes for HA
    • Worker nodes:

      • One or more worker nodes for non-HA
      • Two or more worker nodes for HA and depending on workload type
  • User clusters - You can configure HA for each user cluster independently.

    • Control plane nodes:

      • One control plane node for non-HA
      • Three or more control plane nodes for HA
    • Worker nodes:

      • One or more worker nodes for non-HA
      • Two or more worker nodes for HA