Nomad is a general-purpose cluster orchestrator and scheduler. Up until Nomad 1.3 was released, it had no native support for discovering other applica

Karan Sharma | Understanding Networking in Nomad

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2022-05-15 09:00:05

Nomad is a general-purpose cluster orchestrator and scheduler. Up until Nomad 1.3 was released, it had no native support for discovering other applications running in the cluster. This is sort of a very elementary requirement when scheduling tasks in a cluster. Nomad relies on Consul to discover other "services" and has first class support for registering and fetching service records which makes things easier. Consul provides the records via various mechanisms such as a REST API, DNS and Consul Templates which render the exact IP/Port of the service in a Go template that can be injected into your application.

I've been using Nomad since quite some time (both at work and for my self hosted instance) however I've often tripped when it comes to Networking. Nomad has a lot of simple concepts and it all "clicks" once you understand and recognise various patterns that can be used to connect the applications. A major learning curve for someone new to Nomad and trying to integrate Consul is that the person now has to first understand how Consul works, deploy a Consul cluster and this creates a lot of friction amongst newcomers to Nomad. Nomad 1.3 solves a part of this issue (i.e. no need to run Consul for basic service discovery) and is a great fit for just getting started with Nomad based networking. However, in this post I'd like to go through all the different networking patterns I've known or used in production and make an attempt at simplifying these concepts for Nomad beginners.

We'll start off with the simplest usecase: You have a redis container and you want to expose that to the host. The docker run equivalent to what we wanna do is:

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