Update to fix nginx proxy config (#186)

Co-authored-by: Jax Gauthier <jax@gauthier.id>

src/en/administration/install_docker.md

@@ -18,13 +18,91 @@ sudo chown -R 991:991 volumes/pictrs
 
 If you'd like a different database password, you should also change it in the `docker-compose.yml` **before** your first run.
 
+You'll also need to copy the following to `nginx.conf` in the root of your `lemmy` folder. This will ensure the proxy setup by `docker-compose` will function properly:
+
+```
+worker_processes 1;
+events {
+    worker_connections 1024;
+}
+http {
+    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";
+    }
+
+    server {
+        # this is the port inside docker, not the public one yet
+        listen 80;
+        # change if needed, this is facing the public web
+        server_name localhost;
+        server_tokens off;
+
+        gzip on;
+        gzip_types text/css application/javascript image/svg+xml;
+        gzip_vary on;
+
+        # Upload limit, relevant for pictrs
+        client_max_body_size 20M;
+
+        add_header X-Frame-Options SAMEORIGIN;
+        add_header X-Content-Type-Options nosniff;
+        add_header X-XSS-Protection "1; mode=block";
+
+        # frontend general requests
+        location / {
+            # distinguish between ui requests and backend
+            # don't change lemmy-ui or lemmy here, they refer to the upstream definitions on top
+            set $proxpass "http://lemmy-ui";
+
+            if ($http_accept = "application/activity+json") {
+              set $proxpass "http://lemmy";
+            }
+            if ($http_accept = "application/ld+json; profile=\"https://www.w3.org/ns/activitystreams\"") {
+              set $proxpass "http://lemmy";
+            }
+            if ($request_method = POST) {
+              set $proxpass "http://lemmy";
+            }
+            proxy_pass $proxpass;
+
+            rewrite ^(.+)/+$ $1 permanent;
+            # Send actual client IP upstream
+            proxy_set_header X-Real-IP $remote_addr;
+            proxy_set_header Host $host;
+            proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
+        }
+
+        # backend
+        location ~ ^/(api|pictrs|feeds|nodeinfo|.well-known) {
+            proxy_pass "http://lemmy";
+            # proxy common stuff
+            proxy_http_version 1.1;
+            proxy_set_header Upgrade $http_upgrade;
+            proxy_set_header Connection "upgrade";
+
+            # Send actual client IP upstream
+            proxy_set_header X-Real-IP $remote_addr;
+            proxy_set_header Host $host;
+            proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
+        }
+    }
+}
+```
+
 After this, have a look at the [config file](configuration.md) named `lemmy.hjson`, and adjust it, in particular the hostname, and possibly the db password. Then run:
 
 `docker-compose up -d`
 
 You can access the lemmy-ui at `http://localhost:80`
 
-To make Lemmy available outside the server, you need to setup a reverse proxy, like Nginx. You can use the following simple proxy:
+To make Lemmy available outside the server, you need to set up a reverse proxy, like Nginx. You can use the following simple proxy:
+
+Note: If you are planning on running your reverse proxy on port 80, you'll need to update the docker-compose.yml file you just downloaded to change the internal proxy's listening port. If you are setting up Let's Encrypt on the same machine, you'll need to do this.
 
 ```
 server {
@@ -39,6 +117,8 @@ server {
 }
 ```
 
+### Let's Encrypt
+
 You should also setup TLS, for example with [Let's Encrypt](https://letsencrypt.org/). [Here's a guide for setting up letsencrypt on Ubuntu](https://www.digitalocean.com/community/tutorials/how-to-secure-nginx-with-let-s-encrypt-on-ubuntu-20-04).
 
 For federation to work, it is important that you do not change any headers that form part of the signature. This includes the `Host` header - you may need to refer to the documentation for your proxy server to pass through the `Host` header unmodified.