Good luck on your Nix journey! Happy to help if you have questions.

Of all the tech I use, I think Nix is the most ‘avant-garde’ in that it is super different from the usual methods (scripting, stateful things), but works very well once past the paradigm shift and the learning curve that entails.

Nomad has host volumes - so you can tell it to mount a folder from the machine on the container, and it will only schedule that container on machines that have that folder. So yes, effectively you pin the workload, thus introducing a SPOF - I do not love it but Grafana only supports sqlite and postgres, so making those HA would require failover setups which is a bit much for a homelab :')

For backing up, you can use the sqlite command periodically (do cron job or Nomad periodic job) and then upload the backup to some external, safe storage (could be seaweedfs or S3!). For postgres you can use something like this.

I have never used NFS, but I think it would fare much better than seaweedfs because it uses Fuse to implement CSI. So for NFS I am sure the protocol would consider half-assed writes

would be the same for any CSI plugin

No, it would depend on the CSI plugin and how it is implemented. Ceph for example I know it has several, and cloud providers offer CSI volumes for their block storage (AWS EBS, GCP PD), and they will all perform differently. See this comment from a seaweedfs issue:

[…] It is always better to run databases on host volumes if you can (or on volumes provided by AWS EBS or similar). But with Seaweedfs especially if you are running postgres with seaweedfs-csi volume be prepared for data corruption. Seaweefs-csi uses FUSE, if anything happens to seaweedfs-csi (Nomad client restart, docker restart, OOM) mount will be lost and data corruption will happen.

Running on CEPH (since CEPH CSI using Kernel driver not FUSE) is acceptable if you fine with low TPS.

I found it was easier to make recoverable, backed up, host volumes than to make DBs run on high availability filesystems like seaweedfs (I admit I have not tried Ceph - the deployment looked a bit complicated/overkill for a homelab).

Postgres and sqlite are just not made for that environment. To run a high-availability DB, it is better to run a distributed DB made for that (think etcd, cassandra) than to run a non-distributed DB on top of a distributed filesystem.

Good luck! :)

The problem with using seaweedfs to a back your DBs is more on the filesystem than the implementations of POSIX features. When you are writing to a file, and the connection to seaweedfs breaks (container restart, wifi, you name it), then you might end up with a half-written file. If you upload pictures, this is unlikely, but DBs are doing several writes per second usually. So it is more likely one of those gets interrupted. In my case, my grafana sqlite DB would get corrupted every other week.

What I recommend is using DBs natively in your node’s filesystem, and backing them up to seaweedfs periodically instead. That way your DBs ‘work’ but you can get them running again, and the backup is replicated in the distributed filesystem.

Good question! So it depends, but TLDR: imo it’s worth it, or it’s fine, but it’s easy to try yourself and see

most services in their docs will show how to deploy with kubernetes or docker, but rarely Nomad

You are absolutely correct, but I do find that for the large large majority of things, either you can find an online Nomad config, or the Nomad config is easy enough to translate from Docker compose. Only some complicated larger deployments (think Immich) are harder to translate, but even then it just takes some trial and error. I really do think that extra trouble of translating is very much worth the pain you save yourself in terms of deploying k8s though. You might spend a bit longer typing out the Nomad job file yourself, but in exchange you are thankfully not maintaining the k8s cluster.

As far Nomad-specific documentation goes, I think it the official one is more than good enough.

You mentioned compatibility. So far I have not found anything I really wanted that was not possible to set up in Nomad. Nomad does CNI and CSI, which is the same API k8s uses, so thinkgs working there will work for Nomad. Other things you would use with docker compose or k8s don’t work with Nomad, but you don’t need them (for example: portainer or metrics exporters) because Nomad has them natively already (this blog discusses that).

As you can see I am pretty opinionated towards Nomad - I have been using it in my previous job in prod, and in my home-lab for a year now, and I am very happy with it. If you would like to read more I recommend this blog post. For Nomad on NixOS I wrote this one.

For now my advice is: just try nomad yourself (as simple as running nomad agent -dev on your laptop), run the tutorial, and see if it was easy enough that you see yourself using it for the rest of your containers. If you need more help you are welcome to DM me :)

I recommend starting with ZeroToNix’s docs and then moving on to nixos.wiki, but here is a minimal, working example that I could deploy to a hetzner VPS that only has nix and ssh installed:

{ config, pkgs, ... }: {
  # generated, this will set up partitions and bootloader in a separate file
  imports = [ ./hardware-configuration.nix ];
  zramSwap.enable = true;
  networking.hostName = "miki";
  # configures SSH daemon with a public key so we can ssh in again
  services.openssh.enable = true;
  users.users.root.openssh.authorizedKeys.keys = [ ''ssh-ed25519 AAAAC3NzaC1lNDI1NTE5AAAAIPJ7FM3wEuWoVuxRkWnh9PNEtG+HOcwcZIt6Qg/Y1jka'' ];
  # creates a timmy user with sudo access and wget installed
  users.users.timmy = {
    isNormalUser = true;
    extraGroups = [ "networkmanager" "wheel" "sudo" ];
    packages = with pkgs; [ wget ];
  };
  # open up SSH port
  networking.firewall.allowedTCPPorts = [ 22 ];
  # start nginx, assumes HTML is present at `/var/www`
  services.nginx = {
    enable = true;
    virtualHosts."default" = {
      forceSSL = true;            # Redirect HTTP clients to an HTTPs connection
      default = true;             # Always use this host, no matter the host name
      root = /var/www;        # Set the web root to ser
    };
  };
  system.stateVersion = "22.11";
}

This sets up a machine, configures the usual stuff like the ssh daemon, creates a user, and sets up an nginx server. To deploy it you would run nixos-rebuild --target-host root@10.0.0.1 switch. Other tools exist (I use colmena but the idea is the same). Note how easy it was to set up nginx! If I was setting Nomad up, I would just do services.nomad.enable = true.

As you can see some things you will have to learn (the nix language, what the configs are…) but I think it is worth it.

I struggled a bit to get it up and running well, but now I am happy with it. It’s not too hard to deploy (at least easier than the alternatives), it has CSI which for me was big, and it has erasure coding. The dev that maintains it (yes, the one dev) is very responsive.

It has trade offs, so depending on your needs, I recommend it. Backing store for stateful workloads like postgres DBs? Absolutely not. Large S3 store (with an option for filesystem mount) for storing lots of files? Yes! In that regard it’s good for stuff like Lemmy’s pictrs or immich. I use it as my own Google drive. You can easily replicate in your own cluster, or back it up to an external cloud provider. You can mount it via FUSE on your personal machine too.

Feel free to browse through my setup - if you have specific questions I am happy to answer them.

I see no one else commented my stack, so I suggest:

Nomad for managing containers if you want something high availability. Essentially the same as k8s but much much much simpler to deploy, learn, and maintain. Perfect for homelabs imo. Most of the concepts of Nomad translate well to k8s if you do want to learn it later. It integrates really well with Terraform too if you are also hoping to learn that, but it’s not a requirement.

NixOS for managing the bare metal. It’s a lot more work to learn than say, Debian, but it is just as stable, and all configuration will be defined as code, down to the bootloader config (no bash scripts!). This makes it super robust. You can also deploy it remotely. Once you grow beyond a handful of nodes it’s important to use a config management tool, and Nix has been by far my favourite so far.

If you really want everything to be infra-as-code, you can manage cloud providers via Terraform too.

For networking I use wireguard, and configure it with NixOS. Specifically, I have a mesh network where every node can reach every node without extra hops. This is a requirement if you don’t want a single point of failure (hub and spoke) to disconnect your entire cluster.

Everything in my setup is defined ‘as-code’, immutable, and multi-node (I have 7 machines) which seems to be what you want, from what you say in your post. I’ll leave my repo here, and I’m happy to answer questions!

–

My opinions on the alternatives:

Docker compose is great but doesn’t scale if you want high availability (ie, have a container be rescheduled on node failure). If you don’t want higher availability, anything more than docker might be overkill.

Ansible and Puppet are alright but are super stateful, and require scripting. If you want immutability you will love Nix/NixOS

k8s works (I use it at work) but is extremely hard to get right, even for well-resourced infra teams. Nomad achieves the same but with the leanings of having come afterwards, and without the history.

Yep I am using traefik -> nginx. I simply add the traefik tags to the nginx service. I didn’t include that in the example file to keep it simple.

As for the storage, I use SeaweedFS (has a CSI plugin, really cool, works well with nomad) but as a CSI volume it’s not suitable for backing postgres’ filesystem. The lookups are so noticeably slower that your Lemmy instance will be laggy. So I decided to use a normal host volume, so the DB writes to disk directly, and you can back that up to an S3-compatible storage with this (also cool). Could be SeaweedFS, AWS, Backblaze…

I think SeaweedFS is suitable for your pictrs storage though, be it through its S3 API (supported by pictrs) or through a SeaweedFS CSI volume that stores the files directly.

I hope that answers it! Do let me know what you end up with

Have you considered running your Lemmy instance on more than a single machine? If it is possible to run two lemmy containers anyway (ie, lemmy is not a singleton), why not run them on separate machines? With load balancing you could achieve a more stable experience. It might be cheaper to have many mediocre machines rather than a single powerful one too, as well as more sustainable long-term (vertical vs horizontal scaling).

The downside would be that the set-up would be less obvious than with Docker compose and you would probably need to get into k8s/k3s/nomad territory in order to orchestrate a proper fleet.

There are dozens of us!

• nomad fmt was applied already - granted it is not a small easy to read job file, it might be easier to split it up into separate jobs
• I will look into making this into a Pack - I have never built one because I have never shared my config like this before. I don’t know how popular they are among selfhosters either!

I think an easy first step would be to contribute a sample job file like this into the Lemmy docs website. Then people can adapt to their setups. I find there is a lot more to configure in Nomad than in Docker compose for example because you stop assuming everything will be in a single box, which changes networking considerably. There is also whether to use Consul, Vault etc.