silikonproductions.blogg.se - Envoy panic mode

#Envoy panic mode how to#

We can create a headless service by setting the. This service type is intended to be used in scenarios when we want to implement load balancing, and maintaining the connections to the upstream pods ourselves, which is exactly what we can do with Envoy. In Kubernetes there is a specific kind of service called a headless service, which happens to be very convenient to be used together with Envoy’s STRICT_DNS service discovery mode.Ī headless service doesn’t provide a single IP and load balancing to the underlying pods, but rather it just has DNS configuration which gives us an A record with the pod’s IP address for all the pods matching the label selector. Create the headless service for our application In the remainder of this post I will describe the steps necessary to deploy Envoy to be used as a load balancer in front of a service running in Kubernetes. (This was due to the internals of how this service worked, it couldn’t efficiently run more than a handful requests in parallel.)ĭue to the above characteristics, the round robin load balancing algorithm was not a good fit, because often-by chance-multiple requests ended up on the same node, which made the average response times much worse than what the cluster would’ve been capable achieving, given a more uniformly spread out load. Processing many requests in parallel degraded the response time.The processing of the requests was CPU-intensive, practically the processing of one request used 100% of one CPU core.

The requests were long running with varied response times, ranging from 100ms to seconds.

In my case this was an issue, because my service had the following characteristics. I was using the Google Kubernetes Engine, where every load balancer service is mapped to a TCP-level Google Cloud load balancer, which only supports a round robin load balancing algorithm. The exact way a load balancer service works depends on the hosting environment-if it supports it in the first place.

It supports various load balancing algorithms, among others “Least Request”.īefore starting to use Envoy, I was accessing my service in Kubernetes through a object of the type, which is a pretty typical way to access services from the outside in Kubernetes.

This made it easy to use with a headless service in Kubernetes.

It has built-in support for a service discovery technique it calls STRICT_DNS, which builds on querying a DNS record, and expecting seeing an A record with an IP address for every node of the upstream cluster.

Besides being able to be controlled dynamically with a control plane API, it also supports a simple, hard-coded YAML-based configuration, which was convenient for my purposes, and made it easy to get started.

I chose Envoy as a load balancer proxy for a number of reasons.

It’s high-performant, has a low resource footprint, it supports dynamic configuration managed by a “control plane” API, and provides some advanced features such as various load balancing algorithms, rate limiting, circuit braking, and shadow mirroring.

#Envoy panic mode how to#

In this post I’m not going to do a comparison of these, but rather just focus on one specific scenario: how to use Envoy as a load balancer for a service running in Kubernetes.Įnvoy is a “high performance C++ distributed proxy”, originally implemented at Lyft, but since then have gained a wide adoption. Beside the older players, there are several new proxy technologies popping up in recent years, implemented in various technologies, popularizing themselves with different features, such as easy integration to certain cloud providers (“cloud-native”), high performance and low memory footprint, or dynamic configuration.Īrguably the two most popular “classic” proxy technologies are NGINX (C) and HAProxy (C), while some of the new kids on the block are Zuul (Java), Linkerd (Rust), Traefik (Go), Caddy (Go) and [ Envoy (C++).Īll of these technologies have different feature sets, and are targeting some specific scenarios or hosting environments (for example Linkerd is fine-tuned for being used in Kubernetes). In today’s highly distributed word, where monolithic architectures are increasingly replaced with multiple, smaller, interconnected services (for better or worse), proxy and load balancing technologies seem to have a renaissance. How to use Envoy as a Load Balancer in Kubernetes