Updating default nginx config

Signed-off-by: Rajesh Rajendran <rjshrjndrn@gmail.com>

images/proxy/nginx.conf

@@ -23,13 +23,18 @@ http {
     access_log  /var/log/nginx/access.log  main;
 
     # Shared dictionary to store metrics
-    lua_shared_dict prometheus_metrics 10M;
+    lua_shared_dict prometheus_metrics 100M;
     lua_package_path "/etc/nginx/lua_modules/?.lua";
+    # Defining upstream cache status for nginx metrics
+    map $upstream_cache_status $cache_status {
+      default  $upstream_cache_status;
+      ''       "NONE";
+    }
     # 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"})
+          "nginx_http_requests_total", "Number of HTTP requests", {"host", "status", "request_method", "cache_status"}
       metric_latency = prometheus:histogram(
         "nginx_http_request_duration_seconds", "HTTP request latency", {"host"})
       metric_connections = prometheus:gauge(
@@ -38,7 +43,7 @@ http {
 
     # Collecting metrics
     log_by_lua '
-      metric_requests:inc(1, {ngx.var.server_name, ngx.var.status, ngx.var.request_method})
+      metric_requests:inc(1, {ngx.var.server_name, ngx.var.status, ngx.var.request_method, ngx.var.cache_status})
       metric_latency:observe(tonumber(ngx.var.request_time), {ngx.var.server_name})
     ';