CODEWITHSUNDEEP
kubernetesservice-discoveryleader
F21
F21

Reputation: 33391

How can pods within a kubernetes replica set discover and talk to each other without the kubernetes API?

I have an application that uses raft to elect a leader out of multiple instances. These instances use the gossip protocol, so it just needs to know another instance to discover the rest.

I plan to run each instance as a kubernetes pod, with replication manage by a replication controller. I will also put a service in front of these nodes so that other apps in the cluster can talk to it.

My problem is: How can I get the pods within the replica set to discover each other without the kubernetes API? Is this possible through DNS, or does kubernetes provides some environment variables?

Upvotes: 2

Views: 1563

Answers (1)

F21
F21

Reputation: 33391

The solution is to use a headless service. For example, we can deploy a headless service called myservice-discovery. Because the service is headless, it does not do any load-balancing or get a cluster ip address. To get the ip addresses of the pods, you then query the DNS server for myservice-discovery.mycluster to get a list of A records.

You can also set up a second normal (non-headless) service if the pods also need to be accessible to other services and pods.

Upvotes: 3

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