Continental Innovates with Rancher and Kubernetes
This guide outlines a reference architecture for installing Rancher on an RKE Kubernetes cluster in a vSphere environment, in addition to standard vSphere best practices as documented by VMware.
A load balancer is required to direct traffic to the Rancher workloads residing on the RKE nodes.
Leverage the use of an external (hardware or software) load balancer that has inherit high-availability functionality (F5, NSX-T, Keepalived, etc).
In the event of a Disaster Recovery activity, availability of the Load balancer configuration will expedite the recovery process.
Configure the Load balancer to automatically mark nodes as unavailable if a health check is failed. For example, NGINX can facilitate this with:
Avoid implementing a software load balancer within the management cluster.
Configure appropriate Firewall / ACL rules to only expose access to Rancher
To facilitate consistency across the deployed Virtual Machines across the environment, consider the use of “Golden Images” in the form of VM templates. Packer can be used to accomplish this, adding greater customisation options.
Doing so will ensure node VM’s are spread across multiple ESXi hosts - preventing a single point of failure at the host level.
Doing so will ensure node VM’s are spread across multiple datastores - preventing a single point of failure at the datastore level.
It’s important to follow K8s and etcd best practices when deploying your nodes, including disabling swap, double-checking you have full network connectivity between all machines in the cluster, using unique hostnames, MAC addresses, and product_uuids for every node.
Deploy etcd members within a single data center where possible to avoid latency overheads and reduce the likelihood of network partitioning. For most setups, 1Gb connections will suffice. For large clusters, 10Gb connections can reduce the time taken to restore from backup.
Each node used should have a static IP configured. In the case of DHCP, each node should have a DHCP reservation to make sure the node gets the same IP allocated.
ETCD is very sensitive to write latency. Therefore, leverage SSD disks where possible.
Rancher stores its data in the ETCD datastore of the Kubernetes cluster it resides on. Like with any Kubernetes cluster, perform frequent, tested backups of this cluster.
Incorporate the Rancher management node VM’s within a standard VM backup policy.