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Simple nginx config (lemmy.ml)

submitted 1 year ago by Valmond@lemmy.ml to c/lemmy_support@lemmy.ml

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Hello all!

I finally got my Lemmy instance up and running yay!

It runs on a local machine, I have nginx installed and my website pointing onto it.

lemmy.mindoki.com => my_static_ip(port 80) => local_ip => nginx

In ngunx I just set up a hello world message, and it works out. lemmy.mindoki.com shows it.

Now, my Lemmy instance is accessible on 0.0.0.0:1236 but obviously only from inside the hosting machine itself.

I have tinkered a bit with the nginx.conf but I feel there is lot of things to do wrongly, especially as it's 'dynamic', but also it seems like a schoolbook example (for Lemmy, so no hits on my favourite search engine), so maybe someone has a working nginx.conf file to spare for a basic setup like this?

Thanks a bunch!

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[–] Max_P@lemmy.max-p.me 2 points 1 year ago (8 children)

So, the part that selects what hostname it serves is the server_name directive. What those http://lemmy and http://lemmy-ui point to is the backend services. In this case, it's assuming the Docker setup where the containers are named lemmy and lemmy-ui respectively. They're completely invisible to the user, and in this case relies on Docker directing those names to the appropriate containers automatically. You don't need to change those, unless you're not using Docker. If you're not using Docker, then those need to point to the address to reach lemmy and lemmy-ui. So for example, you might want to set that to http://127.0.0.1:1236.

Essentially, traffic comes in at port 80/443 or whatever your listen directives say, then NGINX receives the connection and processes the host header in the request to match it against which server{} block serves that server_name, or falls back to whichever server block defines listen ..... default_server, or if there isn't any, it usually falls into whichever server block happens to be first loaded in by the server. Pretty much only the listen and server_name directives are relevant here in terms of handling incoming traffic from the outside, mostly. Things like ssl_* will also configure how to handle incoming HTTPS connection, but that happens slightly after the server block has been identified using the listen and server_name directives. Most other directives are about how to handle the request once it's in the server block.

Then, it processes the request entirely within that server block. In this particular case, there's a bit of logic so that it proxies it to lemmy-ui unless it's an ActivityPub request or anything not a GET/HEAD request, in which case it tries to proxy it to the lemmy backend service. That's what the if directives accomplish here. Usually we put those in location blocks, in this case the location / block so it handles all paths except other location blocks that override it. Some directives can be put directly in the server block and will apply to all locations unless overridden. Technically NGINX processes the location blocks first in order of precision (ie. /foo/bar/42/comments is more specific than /foo, and when there's a tie it's based on configuration order in the config file).

There's also a location block to map some URLs like /.well-known and /pictrs that also gets proxied to the lemmy backend directly. The way those work is say, you want to handle something at http://example.com/demo, you can add a location /demo {} block and the directives in that block will only apply when the URL is /demo/*.

Does that clarify things for you?

[–] Valmond@lemmy.ml 1 points 1 year ago (7 children)

Thank you and yes, yes it does clarify a lot how nginx is working!

I'm trying to use use the conf file coming with lemmy docker install, and after some searching I don't even know if this is deprecated or not (it's in the http{} ), or how I should tell nginx the information about where to find the docker devices:

upstream lemmy {
    # this needs to map to the lemmy (server) docker service hostname
    server "lemmy:8536";
}
upstream lemmy-ui {
    # this needs to map to the lemmy-ui docker service hostname
    server "lemmy-ui:1234";
}

Also, shouldn't I tell nginx to listen to port 80?

Also, I get this error when I run "sudo nginx -s reload" and I don't even understand what it means:

nginx: [emerg] host not found in upstream "lemmy" in /etc/nginx/nginx.conf:53

Thank you again, I'm a slow learner!

[–] Max_P@lemmy.max-p.me 2 points 1 year ago (6 children)

There's two NGINX servers in the Docker setup: one on the inside, and one on the outside/on the host.

If you run NGINX from the host or outside of the docker-compose, lemmy and lemmy-ui won't resolve because that only exists within Docker. It does a bit of magic that essentially amounts to putting these in the containers' /etc/hosts and maps to the internal IPs that the containers get. Docker has some sort of virtual router built-in, each compose gets its own virtual network and everything.

If you use the Docker setup, you can use the configs I linked from the Ansible repo essentially as-is with minor tweaks. The internal NGINX config can be kept completely unchanged, and the outside one only needs minor tweaks to set up your own hostname and the port for the internal one. You only need to fill in the {{domain}} and {{lemmy_port}} placeholders in the outside one. The example outside NGINX config already listens to both 80 and 443.

Basically with the suggested setup, you go Internet -> your server (port 80/443) -> the internal NGINX in Docker (port 1236) -> lemmy/lemmy-ui.

[–] Valmond@lemmy.ml 1 points 1 year ago

Good morning and thank you, I'll use your recommended config asap, and then be back with more questions most probably :-) !

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