Can a service advertise multiple ports?

Nomad
3

Since Nomad does not seem to be able to advertise multiple ports for a service, I found a workaround for my scenario. I am defining the second dynamic port and then saving it to the metadata. Consul is able to pass that metadata on to Prometheus where I am able to use relabel_configs to have Prometheus scrape the correct port dynamically while still using consul_sd_configs.

job "awesome-api" {

  group "awesome-group" {

    network {
      port "http"    { host_network = "private" }
      port "metrics" { host_network = "private" }
    }

    service {
      name    = "awesome-api"
      port    = "http"
    }

    meta {
      metrics-port = "${NOMAD_PORT_metrics}"
    }

    task "gateway" {
      driver = "exec"
      config {
        command = "${NOMAD_ALLOC_DIR}/api/app"
        args    = ["-config", "config.json"]
      }

      template {
        destination = "config.json"
        data        = <<-EOT
          {
            "http_address"    : "{{ env "NOMAD_IP_http" }}:{{ env "NOMAD_PORT_http" }}",
            "metrics_address" : ":{{ env "NOMAD_PORT_metrics" }}",
          }
        EOT
      }
    }

  }
}

Prometheus config snippet:

...

- job_name: 'all-services-consul-sd'
  metrics_path: "/"
  consul_sd_configs:
  - server: 'localhost:8500'

  relabel_configs:
    - source_labels: [__meta_consul_service_address,__meta_consul_service_metadata_metrics_port]
      separator: ';'
      regex: (.*);(\d{4,5})
      target_label:  '__address__'
      replacement: '$1:$2'
      action: 'replace'

...