Registering a Consul Service in a Custom Consul Namespace via Nomad Job – HashiCorp Help Center

Introduction:

Consul provides service discovery and configuration capabilities, while Nomad offers a powerful job scheduler and orchestrator. By integrating these two tools, you can register a service in a custom Consul namespace using a Nomad job. This article will guide you through the process, assuming you have Consul and Nomad installed and configured/integrated correctly.

Prerequisites:

Nomad v0.10.4 or greater
a Nomad environment with Nomad and Consul installed.
Consul Enterprise Version would be required with a license which is having a capability to support namespace features.

Procedure:

Step 1: Create a namespace in Nomad using below CLI command -

nomad namespace apply nomad-test

Step 2: Create a namespace in Consul using below CLI command -

consul namespace create -name consul-test

Step 3: Create a Nomad job file: Open a text editor and create a new file to define your Nomad job configuration using the HCL (HashiCorp Configuration Language) or JSON syntax. Below is the sample example file for reference -

job "example" {
  datacenters = ["dc1"]

  ## Nomad namespace where job will be registered.
  namespace = "nomad-test" 

  group "cache" {
    consul {
      ## Consul namespace where service will be registered.
      namespace = "consul-test"
    }

    network {
      mode = "bridge"
    }

    service {
      name = "example-test"
      port = "9001"
    }

    task "redis" {
      driver = "docker"

      config {
        image = "redis:7"
      }
    }
  }
}

Step 4: Submit the job to Nomad by saving the Nomad job file with an appropriate name and extension, such as "example.nomad" (Above sample job name is example). Then, open a terminal or command prompt and navigate to the directory containing the job file. Submit the job to Nomad using the following command:

nomad job run example.nomad

Step 5: After submitting the job, verify the same via Nomad UI and CLI.

Nomad UI -

Nomad CLI -

ID      Type    Priority Status  Submit Date
example service 50       running 2023-05-24T04:33:09Z

You can also see in the Nomad job's allocation that the service has been registered in Consul. Here is the snippet for your reference -

Step 6: Verify service registration in the custom Consul namespace:

After submitting the job file, Nomad will schedule and deploy the service while registering it in the custom Consul namespace.
To verify the registration, you can use the Consul API or the Consul UI.
In Consul UI you can verify the service. Service will be present in Consul UI as below -
For example, you can use the following cURL command to query the Consul API:

curl http://localhost:8500/v1/catalog/service/example-test?ns=test

Notes -

In the above API command replace the name of the service and namespace accordingly as per your job file.
Adjust the API endpoint and replace "localhost" if your Consul agent is running on a different host.

Conclusion:

By following the steps outlined in this article, you can leverage Nomad's capabilities to register a service in a custom Consul namespace. This integration allows for efficient service discovery and configuration within your distributed system.

Reference URL -

Consul Service Register - https://developer.hashicorp.com/consul/docs/services/usage/register-services-checks

Nomad Job Deployment - https://developer.hashicorp.com/nomad/docs/commands/job/deployments

Consul HTTP API - https://developer.hashicorp.com/consul/api-docs

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