Add Gunicorn requirement blocks

docs/installation/wsgi.md

@@ -1,25 +1,23 @@
-For production builds, you'll want to have a real WSGI front end instead of the built in Flask developer web server. For time's sake, Ubuntu 18.04 instructions are provided. That said, this is a pretty generic setup and should be easily replicable to other platforms.
+For production builds, you'll want to have a real WSGI front end instead of the built in Flask developer web server. While any WSGI could be used, [Gunicorn](https://gunicorn.org/) is the recommended and default WSGI for hyperglass.
 
-## Gunicorn Installation
+!!! info "Alternative WSGIs"
+    If you choose to use a different WSGI, be sure to look closely at `hyperglass/hyperglass/gunicorn_config.py.example` to properly replicate configurations for Prometheus metrics with multiple workers, single-worker Sass compilation, and Redis testing.
 
-[Gunicorn](https://gunicorn.org/) is a WSGI server written in Python.
-
-### Install
-```console
-$ pip3 install gunicorn
-```
-
-### Configure
+## Configure
 
 Migrate the example Gunicorn configuration file:
+
 ```console
 $ cd /opt/hyperglass/
 $ python3 manage.py migrate-gunicorn
 ```
 
 Open `hyperglass/hyperglass/gunicorn_config.py`, and adjust the parameters to match your local system. For example, make sure the `command` parameter matches the location of your `gunicorn` executable (`which gunicorn`), the `pythonpath` parameter matches the location where hyperglass is installed, and that the `user` parameter matches the user you're running hyperglass as.
 
-#### Permissions
+!!! warning "Reverse Proxy Required"
+    Gunicorn is not designed to be a front-end web server, and therefore requires the use of a reverse proxy of some kind. The Gunicorn development team recommends the use of [NGINX](https://www.nginx.com/), for which [installation instructions have been provided](../reverseproxy).
+
+### Permissions
 
 Gunicorn requires read/write/executable access to the entire `hyperglass/hyperglass` directory in order to read its configuration and execute the python code. If running gunicorn as `www-data`, fix permissions with:
 
@@ -28,5 +26,5 @@ Gunicorn requires read/write/executable access to the entire `hyperglass/hypergl
 # python3 manage.py update-permissions --user <user> --group <group>
 ```
 
-!!! note "File Ownership"
+!!! info "File Ownership"
     If the `--user` and `--group` options are not specified, `www-data` will be used.