varnish config/docs (#342)

[akkoma] / docs / docs / configuration / optimisation / varnish_cache.md

diff --git a/docs/docs/configuration/optimisation/varnish_cache.md b/docs/docs/configuration/optimisation/varnish_cache.md
new file mode 100644 (file)
index 0000000..1598354
--- /dev/null
+++ b/docs/docs/configuration/optimisation/varnish_cache.md
@@ -0,0 +1,54 @@
+# Using a Varnish Cache
+
+Varnish is a layer that sits between your web server and your backend application -
+it does something similar to nginx caching, but tends to be optimised for speed over
+all else.
+
+To set up a varnish cache, first you'll need to install varnish. 
+
+This will vary by distribution, and since this is a rather advanced guide,
+no copy-paste instructions are provided. It's probably in your distribution's
+package manager, though. `apt-get install varnish` and so on.
+
+Once you have varnish installed, you'll need to configure it to work with akkoma.
+
+Copy the configuration file to the varnish configuration directory:
+
+    cp installation/akkoma.vcl /etc/varnish/akkoma.vcl
+
+You may want to check if varnish added a `default.vcl` file to the same directory,
+if so you can just remove it without issue.
+
+Then boot up varnish, probably `systemctl start varnish` or `service varnish start`.
+
+Now you should be able to `curl -D- localhost:6081` and see a bunch of
+akkoma javascript.
+
+Once that's out of the way, we can point our webserver at varnish. This
+
+=== "Nginx"
+
+    upstream phoenix {
+        server 127.0.0.1:6081 max_fails=5 fail_timeout=60s;
+    }
+
+
+=== "Caddy"
+
+    reverse_proxy 127.0.0.1:6081
+
+Now hopefully it all works
+
+If you get a HTTPS redirect loop, you may need to remove this part of the VCL
+
+```vcl
+if (std.port(server.ip) != 443) {
+      set req.http.X-Forwarded-Proto = "http";
+      set req.http.x-redir = "https://" + req.http.host + req.url;
+      return (synth(750, ""));
+} else {
+  set req.http.X-Forwarded-Proto = "https";
+}
+```
+
+This will allow your webserver alone to handle redirects.
\ No newline at end of file