mirror of https://github.com/hashicorp/consul
1c2c975b0b
Prior to #13244, connect proxies and gateways could only be configured by an xDS session served by the local client agent. In an upcoming release, it will be possible to deploy a Consul service mesh without client agents. In this model, xDS sessions will be handled by the servers themselves, which necessitates load-balancing to prevent a single server from receiving a disproportionate amount of load and becoming overwhelmed. This introduces a simple form of load-balancing where Consul will attempt to achieve an even spread of load (xDS sessions) between all healthy servers. It does so by implementing a concurrent session limiter (limiter.SessionLimiter) and adjusting the limit according to autopilot state and proxy service registrations in the catalog. If a server is already over capacity (i.e. the session limit is lowered), Consul will begin draining sessions to rebalance the load. This will result in the client receiving a `RESOURCE_EXHAUSTED` status code. It is the client's responsibility to observe this response and reconnect to a different server. Users of the gRPC client connection brokered by the consul-server-connection-manager library will get this for free. The rate at which Consul will drain sessions to rebalance load is scaled dynamically based on the number of proxies in the catalog. |
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| limiter.go | ||
| limiter_test.go | ||