Add profiling doc

Signed-off-by: Gabriel Adrian Samfira <gsamfira@cloudbasesolutions.com>

doc/debugging_and_profiling.md

@@ -0,0 +1,22 @@
+# Debugging and profiling
+
+GARM can optionally enable the golang profiling server. You can then use the usual `go tool pprof` command to start profiling. This is useful if you suspect garm may be bottlenecking in any way. To enable the profiling server, add the following section to the garm config:
+
+```toml
+[default]
+
+debug_server = true
+```
+
+Then restarg garm. You can then use the following command to start profiling:
+
+```bash
+go tool pprof http://127.0.0.1:9997/debug/pprof/profile?seconds=120
+```
+
+Important note on profiling when behind a reverse proxy. The above command will hang for a fairly long time. Most reverse proxies will timeout after about 60 seconds. To avoid this, you should only profile on localhost by connecting directly to garm.
+
+It's also advisable to exclude the debug server URLs from your reverse proxy and only make them available locally.
+
+Now that the debug server is enabled, here is a blog post on how to profile golang applications: https://blog.golang.org/profiling-go-programs
+