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A single user request hits Google’s servers. A user is looking for search results.
In order to deliver those search results, that request will have to hit several different internal services on the way to getting a response.
These different services work together to satisfy the user request. All of these services need to communicate efficiently, they need to scale, and they need to be secure. Services need to have a consistent way of being “observable”–allowing logging and monitoring. Services need to have proper security.
Since every service wants these different features (like communication, load balancing, security), it makes sense to build these features into a common system that can be deployed to every server.
Louis Ryan has spent his years at Google working on service infrastructure. During that time, he has seen massive changes in the way traffic flows through Google. First, the rise of Android, and all of the user traffic from mobile phones. And second, the rise of Google Cloud Platform, which meant that Google was now responsible for nodes deployed by users outside of Google.
These two changes–mobile and cloud–led to an increase in the amount of traffic and the type of traffic. All of this traffic leads to more internal services communicating with each other. How does service networking change in such an environment?
Google’s adaptation to the new networking conditions is to introduce a “service mesh”. A service mesh is a network for services. It provides observability, resiliency, traffic control, and other features to every service that plugs into it.
Each service needs to plug into the service mesh. In Kubernetes, services connect to the mesh through a sidecar. Let me explain the term “sidecar.”
Kubernetes manages its resources in pods, and each pod contains a set of containers. You might have a pod that is dedicated to responding to any user that is requesting a picture of a cat. Within that pod, you not only have the container that serves the cat picture–you also have other “sidecar” containers that help out an application container.
You could have a sidecar that gets deployed next to your application container that handles logging, or a sidecar that helps out with monitoring, or network communications.
If you are using the Istio service mesh, that means that you are using a sidecar called Envoy. Envoy is a sidecar called a “service proxy” that provides configuration updates, load balancing, proxying, and lots of other benefits. If we get all that out of Envoy, why do we need a separate abstraction of a “service mesh”? Because it helps to have a tool that aggregates and centralizes all the different communications among these proxies.
Every service gets a sidecar for a service proxy. Every service proxy communicates with the centralized service mesh.
Louis Ryan joins this episode to explain the motivations for building the Istio service mesh, and the problems it solves for Kubernetes developers.
For the next two weeks, we are covering exclusively the world of Kubernetes. Kubernetes is a project that is likely to have as much impact as Linux–and it is very early days. Whether you are an expert in Kubernetes or you are just starting out, we have lots of episodes to fit your learning curve. To find all of our old episodes about Kubernetes (including a previous show about Istio), download the Software Engineering Daily app for iOS or for Android. In other podcast players, only the most 100 recent episodes are available, but in our apps you can find all 650 episodes–and there is also plenty of content that is totally unrelated to Kubernetes!
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