Add separate read/write rate limits

Author: awlayton

support/proxy/http.d/ratelimit.conf

@@ -1,5 +1,15 @@
-limit_req_zone $binary_remote_addr zone=ip:10m rate=5r/s;
-limit_req zone=ip burst=50 delay=10;
+limit_req_zone $binary_remote_addr zone=read_zone:10m rate=20r/s;
+limit_req zone=read_zone burst=400 delay=40;
+
+# Only limit writes
+map $request_method $write_limit {
+    OPTIONS '';
+    HEAD '';
+    GET '';
+    default $binary_remote_addr;
+}
+limit_req_zone $write_limit zone=write_zone:10m rate=5r/s;
+limit_req zone=write_zone burst=50 delay=10;
 
 # Use 429 (Too Many Requests) for rate limit responses
 limit_req_status 429;