Install Multi-Cluster Contrail

Use this procedure to install Contrail in a multi-cluster deployment.

In a multi-cluster deployment, Contrail is the central networking platform and CNI plug-in for multiple distributed workload clusters. The Contrail controller runs in the Kubernetes control plane in the central cluster, and the Contrail data plane components run on the worker nodes in the distributed workload clusters.

Figure 1 shows the cluster you'll create if you follow the multi-cluster setup. The central cluster consists of 3 Kubernetes control plane nodes that run the Contrail controller. This centralized Contrail controller provides the networking for distributed workload clusters. In this example, there is one distributed cluster that consists of 1 control plane node and 2 worker nodes. The worker nodes on the distributed workload cluster contain the Contrail dataplane components.

Figure 1: Multi-Cluster Contrail

The central cluster attaches to the 172.16.0.0/24 network while the distributed workload cluster attaches to the 10.16.0.0/24 network. A gateway sitting between the networks provides access to each other and external access for downloading images from Juniper Networks repositories.

The local administrator is shown attached to a separate network reachable through a gateway. This is typical of many installations where the local administrator manages the fabric and cluster from the corporate LAN. In the procedures that follow, we refer to the local administrator station as your local computer.

Note:

Connecting all cluster nodes together is the data center fabric, which is simplified in the example into a single subnet per cluster. In real installations, the data center fabric is a network of spine and leaf switches that provide the physical connectivity for the cluster.

In an Apstra-managed data center, this connectivity would be specified through the overlay virtual networks that you create across the underlying fabric switches.

To install Contrail in a multi-cluster deployment, you first create the central cluster and then you attach the distributed workload clusters to the central cluster one by one. As with the single-cluster deployment, you'll start with a fresh cluster with no CNI plug-in installed and then you'll install Contrail on it.

Create the central cluster.

Follow the example procedure in Create a Kubernetes Cluster or you can use any other method. Create the cluster with the following characteristics:
- Cluster has no CNI plug-in.
- Disable Node Local DNS.
Tailor the procedure with the desired number of control plane and worker nodes accordingly. You can follow the example deployment shown in Figure 1 or use a different number of nodes.
Modify the deployer_ha_central.yaml manifest as necessary. The deployer_ha_central.yaml manifest that we provide is a sample that you may need to tailor for your setup.
The provided deployer_ha_central.yaml file specifies distinct networks for data (vRouter) traffic, which is different from our example network. In our network, the cluster nodes have a single interface that carries all control and data traffic. We'll need to modify deployer_ha_central.yaml to remove the extra networks.

Edit deployer_ha_central.yaml to remove the following lines that define the contrail-network-config ConfigMap:
Note:
If you're running with 3 control plane nodes in the central cluster as in our cluster example, then you do not need to change the replicas configuration, which is currently set to 3 for all Contrail controller pods. If you're running with a different number of control plane nodes, then modify the replicas configuration accordingly.
Install Contrail on the central cluster.
1. Apply the central cluster manifest ( deployer_ha_central.yaml ). This manifest creates the namespaces and other resources required by the central cluster. It also creates the contrail-k8s-deployer deployment, which deploys Contrail and provides life cycle management for the Contrail components.
2. Check that all pods are now up. This might take a few minutes.
You've now created the central cluster.
Follow Attach a Workload Cluster to create and attach a distributed workload cluster to the central cluster.
Repeat step 4 for every workload cluster you want to create and attach.