nginx: log tarball cache hit/miss info

Author: rmg

nginx.conf

@@ -37,12 +37,13 @@ http {
         set_by_lua_block $npm_config_registry {
             return ngx.shared.npmConfig:get('npm_config_registry')
         }
+        set $ephemeralCacheStatus '-';
         location ~ ^/(.+)/-/(.+\.tgz)$ {
             root               /tmp/npm/store;
+            set                $ephemeralCacheStatus "HIT";
             try_files          /$1/$2 @fetch-tgz;
         }
         location / {
-            set $ephemeralCacheStatus '-';
             # We can't do caching at the proxy level because we can't easily
             # parameterize cache lifetime for proxy_cache. Instead, we do
             # the caching ourselves in Lua using a shared dict.
@@ -66,6 +67,7 @@ http {
         }
         location @fetch-tgz {
             internal;
+            set                $ephemeralCacheStatus "MISS";
             resolver           127.0.0.1 ipv6=off;
             proxy_pass         $npm_config_registry;
             proxy_buffering    on;