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Less featureful than this, but we’ve been doing GRPC client side load balancing with kuberesolver[1] since 2018. It allows GRPC to handle the balancer implement

Less featureful than this, but we’ve been doing GRPC client side load balancing with kuberesolver[1] since 2018. It allows GRPC to handle the balancer implementations. It’s been rock solid for more than half a decade now. 1: https://github.com/sercand/kuberesolver https://github.com/sercand/kuberesolver

azaras 1y ago
What is the difference between Kuberesolver and using a Headless Service? In the README.md file, they compare it with a ClusterIP service, but not with a Headless on "ClusterIP: None". The advantages of using Kuberesolver are that you do not need to change DNS refresh and cache settings. However, I think this is preferable to the application calling the Kubernetes API.
- euank 1y ago
  I can give an n=1 anecdote here: the dns resolver used to have hard-coded caching which meant that it would be unresponsive to pod updates, and cause mini 30s outages. The code in question was: https://github.com/grpc/grpc-go/blob/b597a8e1d0ce3f63ef8a7b62a23ca1fcc3a60678/internal/resolver/dns/dns_resolver.go#L84-L86 https://github.com/grpc/grpc-go/blob/b597a8e1d0ce3f63ef8a7b6... That meant that deploying a service which drained in less than 30s would have a little mini-outage for that service until the in-process DNS cache expired, with of course no way to configure it. Kuberesolver streams updates, and thus lets clients talk to new pods almost immediately. I think things are a little better now, but based on my reading of https://github.com/grpc/grpc/issues/12295 https://github.com/grpc/grpc/issues/12295, it looks like the dns resolver still might not resolve new pod names quickly in some cases.
gaurav324 1y ago
kuberesolver is an interesting take as well. Directly watching the K8s API from each client could raise scaling concerns at very large scale, but it does open the door to using richer Kubernetes metadata for smarter load-balancing decisions. thanks for sharing!
- debarshri 1y ago
  I think with some rate limiting, it can scale. But it might be a security issue as ideally you don't want client to be aware of kubernetes also, it would be difficult to scope the access.
- arccy 1y ago
  if you don't want to expose k8s then there's the generic xds protocol
- deleted 1y ago
  [deleted]
darkstar_16 1y ago
We use a headless service and client side load balancing for this. What's the difference ?
- arccy 1y ago
  instead of polling for endpoint updates, they're pushed to the client through k8s watches
deleted 1y ago
[deleted]
hanikesn 1y ago
I've been using a standardized xds resolver[1]. The benefit here is that you don't have to patch grpc clients. [1] https://github.com/wongnai/xds https://github.com/wongnai/xds
- atombender 1y ago
  Do you know how this compares to the Nginx ingress controller, which has a native gRPC mode?

azaras 1y ago

What is the difference between Kuberesolver and using a Headless Service? In the README.md file, they compare it with a ClusterIP service, but not with a Headless on "ClusterIP: None". The advantages of using Kuberesolver are that you do not need to change DNS refresh and cache settings. However, I think this is preferable to the application calling the Kubernetes API.

euank 1y ago
I can give an n=1 anecdote here: the dns resolver used to have hard-coded caching which meant that it would be unresponsive to pod updates, and cause mini 30s outages. The code in question was: https://github.com/grpc/grpc-go/blob/b597a8e1d0ce3f63ef8a7b62a23ca1fcc3a60678/internal/resolver/dns/dns_resolver.go#L84-L86 https://github.com/grpc/grpc-go/blob/b597a8e1d0ce3f63ef8a7b6... That meant that deploying a service which drained in less than 30s would have a little mini-outage for that service until the in-process DNS cache expired, with of course no way to configure it. Kuberesolver streams updates, and thus lets clients talk to new pods almost immediately. I think things are a little better now, but based on my reading of https://github.com/grpc/grpc/issues/12295 https://github.com/grpc/grpc/issues/12295, it looks like the dns resolver still might not resolve new pod names quickly in some cases.

gaurav324 1y ago

kuberesolver is an interesting take as well. Directly watching the K8s API from each client could raise scaling concerns at very large scale, but it does open the door to using richer Kubernetes metadata for smarter load-balancing decisions. thanks for sharing!

debarshri 1y ago
I think with some rate limiting, it can scale. But it might be a security issue as ideally you don't want client to be aware of kubernetes also, it would be difficult to scope the access.
arccy 1y ago
if you don't want to expose k8s then there's the generic xds protocol
deleted 1y ago
[deleted]

darkstar_16 1y ago

We use a headless service and client side load balancing for this. What's the difference ?

arccy 1y ago
instead of polling for endpoint updates, they're pushed to the client through k8s watches

deleted 1y ago

[deleted]

hanikesn 1y ago

I've been using a standardized xds resolver[1]. The benefit here is that you don't have to patch grpc clients. [1] https://github.com/wongnai/xds https://github.com/wongnai/xds

atombender 1y ago
Do you know how this compares to the Nginx ingress controller, which has a native gRPC mode?