The Ambassador Pattern

Just like the Sidecar pattern, the Ambassador is a container that runs in the same Pod that the application container runs.

Basically, the Ambassador works as a proxy, it handles all the requests coming from the application.

One of the main advantages of this pattern is that there is no need that the application container knows the external services URLs, he will always communicate through localhost with the Ambassador.

The Ambassador is responsible to discover the external service address (this process is also knows as Service Discovery).

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Example

Sharded Redis

• We have a StatefulSet defining 3 replicas of a redis container;
• Also, there is a Service called redis-svc to expose the containers to the cluster;
• We're using twemproxy to act as a proxy to the redis containers;
• Lastly, we defined a Pod called ambassador-example. It defines two containers:
  • nginx: our client application that needs to communicate with the redis
  • twemproxy: who will send the request to one of the redis containers.

As you may see in the above image. All the requests coming from the application are send through localhost to the Ambassador (twemproxy).