Nomad and consul setup - spring-boot

Question

Should I run consul slaves alongside nomad slaves or inside them?
The later might not make sense at all but I'm asking it just in case.
I brought my own nomad cluster up with consul slaves running alongside nomad slaves (inside worker nodes), my deployable artifacts are docker containers (java spring applications).
The issue with my current setup is that my applications can't access consul slaves (to read configurations) (none of 0.0.0.0, localhost, worker node ip worked)
Lets say my service exposes 8080, I configured docker part (in hcl file) to use bridge as network mode. Nomad maps 8080 to 43210.
Everything is fine until my service tries to reach the consul slave to read configuration. Ideally giving nomad worker node IP as consul host to Spring should suffice. But for some reason it's not.
I'm using latest version of nomad.
I configured my nomad slaves like https://github.com/bmd007/statefull-geofencing-faas/blob/master/infrastructure/nomad/client1.hcl
And the link below shows how I configured/ran my consul slave:
https://github.com/bmd007/statefull-geofencing-faas/blob/master/infrastructure/server2.yml
Note: if I use static port mapping and host as the network mode for docker (in nomad) I'll be fine but then I can't deploy more than one instance of each application in each worker node (due to port conflic)

Answer 1

Nomad jobs listen on a specific host/port pair.
You might want to ssh into the server and run docker ps to see what host/port pair the job is listening on.
a93c5cb46a3e image-name bash 2 hours ago Up 2 hours 10.0.47.2:21435->8000/tcp, 10.0.47.2:21435->8000/udp foo-bar
Additionally, you will need to ensure that the consul nomad job is listening on port 0.0.0.0, or the specific ip of the machine. I believe that is this config value: https://www.consul.io/docs/agent/options.html#_bind
All those will need to match up in order to consul to be reachable.
More generally, I might recommend: if you're going to run consul with nomad, you might want to switch to host networking, so that you don't have to deal with the specifics of the networking within a container. Additionally, you could schedule consul as a system job so that it is automatically present on every host.

Answer 2

So I managed to solve the issue like this:
nomad.job.group.network.mode = host
nomad.job.group.network.port: port "http" {}
nomad.job.group.task.driver = docker
nomad.job.group.task.config.network_mode = host
nomad.job.group.task.config.ports = ["http"]
nomad.job.group.task.service.connect: connect { native = true }
nomad.job.group.task.env: SERVER_PORT= "${NOMAD_PORT_http}"
nomad.job.group.task.env: SPRING_CLOUD_CONSUL_HOST = "localhost"
nomad.job.group.task.env: SPRING_CLOUD_SERVICE_REGISTRY_AUTO_REGISTRATION_ENABLED = "false"
Running consul agent (slaves) using docker-compose alongside nomad agent (slave) with host as network mode + exposing all required ports.
Example of nomad job: https://github.com/bmd007/statefull-geofencing-faas/blob/master/infrastructure/nomad/location-update-publisher.hcl
Example of consul agent config (docker-compose file): https://github.com/bmd007/statefull-geofencing-faas/blob/master/infrastructure/server2.yml

Answer 3

Disclaimer: The LAB is part of Cluster Visualization Framework called: LiteArch Trafik which I have created as an interesting exercise to understand Nomad and Consul.
It took me long time to shift my mind from K8S to Nomad and Consul,
Integration them was one of my effort I spent in the last year.
When service resolution doesn't work, I found out it's more or less the DNS configuration on servers.
There is a section for it on Hashicorp documentation called DNS Forwarding
Hashicorp DNS Forwarding
I have created a LAB which explains how to set up Nomad and Consul.
But you can use the LAB seperately.
I created the LAB after learning the hard way how to install the cluster and how to integrate Nomad and Consul.
With the LAB you need Ubuntu Multipass installed.
You execute one script and you will get full functional Cluster locally with three servers and three nodes.
It shows you as well how to install docker and integrate the services with Consul and DNS services on Ubuntu.
After running the LAB you will get the links to Nomad, Fabio, Consul.
Hopefully it will guide you through the learning process of Nomad and Consul
LAB: LAB
Trafik:Trafik Visualizer