mirror of https://github.com/status-im/consul.git
74 lines
3.6 KiB
Plaintext
74 lines
3.6 KiB
Plaintext
---
|
|
layout: docs
|
|
page_title: Multi-Cluster Federation Overview
|
|
sidebar_title: Multi-Cluster Federation
|
|
description: >-
|
|
Installing on multiple Kubernetes clusters.
|
|
---
|
|
|
|
# Multi-Cluster Federation Overview
|
|
|
|
In Consul, federation is the act of joining two or more Consul datacenters.
|
|
When datacenters are joined, Consul servers in each datacenter can communicate
|
|
with one another. This enables the following features:
|
|
|
|
- Services on all clusters can make calls to each other through Consul Service Mesh.
|
|
- [Intentions](/docs/connect/intentions) can be used to enforce rules about which services can communicate across all clusters.
|
|
- [L7 Routing Rules](/docs/connect/l7-traffic-management) can enable multi-cluster failover
|
|
and traffic splitting.
|
|
- The Consul UI has a drop-down menu that lets you navigate between datacenters.
|
|
|
|
## Traditional WAN Federation vs. WAN Federation Via Mesh Gateways
|
|
|
|
Consul provides two mechanisms for WAN (Wide Area Network) federation:
|
|
|
|
1. Traditional WAN Federation
|
|
1. WAN Federation Via Mesh Gateways (newly available in Consul 1.8.0)
|
|
|
|
### Traditional WAN Federation
|
|
|
|
With traditional WAN federation, all Consul servers must be exposed on the wide area
|
|
network. In the Kubernetes context this is often difficult to set up. It would require that
|
|
each Consul server pod is running on a Kubernetes node with an IP address that is routable from
|
|
all other Kubernetes clusters. Often Kubernetes clusters are deployed into private
|
|
subnets that other clusters cannot route to without additional network devices and configuration.
|
|
|
|
The Kubernetes solution to the problem of exposing pods is load balancer services but these can't be used
|
|
with traditional WAN federation because it requires proxying both UDP and TCP and Kubernetes load balancers only proxy TCP.
|
|
In addition, each Consul server would need its own load balancer because each
|
|
server needs a unique address. This would increase cost and complexity.
|
|
|
|
|
|
|
|
### WAN Federation Via Mesh Gateways
|
|
|
|
To solve the problems that occurred with traditional WAN federation,
|
|
Consul 1.8.0 now supports WAN federation **via mesh gateways**. This mechanism
|
|
only requires that mesh gateways are exposed with routable addresses, not Consul servers. We can front
|
|
the mesh gateway pods with a single Kubernetes service and all traffic flows between
|
|
datacenters through the mesh gateways.
|
|
|
|
|
|
|
|
## Network Requirements
|
|
|
|
Clusters/datacenters can be federated even if they have overlapping pod IP spaces or if they're
|
|
on different cloud providers or platforms. Kubernetes clusters can even be
|
|
federated with Consul datacenters running on virtual machines (and vice versa).
|
|
Because the communication between clusters is end-to-end encrypted, mesh gateways
|
|
can even be exposed on the public internet.
|
|
|
|
The only requirement is that the mesh gateways for each cluster can route to
|
|
one another. For example, if using a load balancer service in front of each cluster's
|
|
mesh gateway, the load balancer IP must be routable from the other mesh gateway pods.
|
|
|
|
If using a public load balancer, this is guaranteed. If using a private load balancer
|
|
then you'll need to make sure that its IP is routable from your other clusters.
|
|
|
|
## Next Steps
|
|
|
|
Now that you have an overview of federation, proceed to either the
|
|
[Federation Between Kubernetes Clusters](/docs/k8s/installation/multi-cluster/kubernetes)
|
|
or [Federation Between VMs and Kubernetes](/docs/k8s/installation/multi-cluster/vms-and-kubernetes)
|
|
pages depending on your use case.
|