Issue #000 feat: Updating nginx config to expose metrics

ansible/roles/stack-proxy/templates/nginx.conf

@@ -13,29 +13,66 @@ http {
     include       /etc/nginx/mime.types;
     default_type  application/octet-stream;
 
-    log_format  main  '$http_x_forwarded_for - $remote_addr - $remote_user [$time_local] '
+    lua_load_resty_core off;
+    log_format  main  '$remote_addr - $remote_user [$time_local] '
                       '"$request" $status $body_bytes_sent '
                       '$request_time $upstream_response_time $pipe'
                       '"$http_referer" "$http_user_agent"';
 
     access_log  /var/log/nginx/access.log  main;
 
+    # Shared dictionary to store metrics
+    lua_shared_dict prometheus_metrics 10M;
+    lua_package_path "/etc/nginx/lua_modules/?.lua";
+    # Defining metrics
+    init_by_lua '
+      prometheus = require("prometheus").init("prometheus_metrics")
+      metric_requests = prometheus:counter(
+        "nginx_http_requests_total", "Number of HTTP requests", {"host", "status", "request_method"})
+      metric_latency = prometheus:histogram(
+        "nginx_http_request_duration_seconds", "HTTP request latency", {"host"})
+      metric_connections = prometheus:gauge(
+        "nginx_http_connections", "Number of HTTP connections", {"state"})
+    ';
+
+    # Collecting metrics
+    log_by_lua '
+      metric_requests:inc(1, {ngx.var.server_name, ngx.var.status, ngx.var.request_method})
+      metric_latency:observe(tonumber(ngx.var.request_time), {ngx.var.server_name})
+    ';
+
     sendfile        on;
     #tcp_nopush     on;
     client_max_body_size 60M;
 
-    keepalive_timeout  65;
+    keepalive_timeout  500s;
+    keepalive_requests 200;
+
+    # Nginx connection limit per ip
+    limit_conn_zone $binary_remote_addr zone=limitbyaddr:10m;
+    limit_conn_status 429;
 
     upstream kong {
         server api-manager_kong:8000;
         keepalive 1000;
     }
 
-    #gzip  on;
     upstream player {
         server player_player:3000;
         keepalive 1000;
     }
 
     include /etc/nginx/conf.d/*.conf;
+
+   server {
+     listen 9145;
+     location /metrics {
+       content_by_lua '
+         metric_connections:set(ngx.var.connections_reading, {"reading"})
+         metric_connections:set(ngx.var.connections_waiting, {"waiting"})
+         metric_connections:set(ngx.var.connections_writing, {"writing"})
+         prometheus:collect()
+       ';
+     }
+   }
 }