refactor: explicitely default keepalive to disabled

nginx.tmpl

@@ -249,7 +249,7 @@
     {{- if exists $override }}
     include {{ $override }};
     {{- else }}
-        {{- $keepalive := first (keys (groupByLabel .Containers "com.github.nginx-proxy.nginx-proxy.keepalive")) }}
+        {{- $keepalive := coalesce (first (keys (groupByLabel .Containers "com.github.nginx-proxy.nginx-proxy.keepalive"))) "disabled" }}
     location {{ .Path }} {
         {{- if eq .NetworkTag "internal" }}
         # Only allow traffic from internal clients
@@ -263,14 +263,14 @@
         root {{ trim .VhostRoot }};
         include fastcgi_params;
         fastcgi_pass {{ trim .Upstream }};
-            {{- if $keepalive }}
+            {{- if ne $keepalive "disabled" }}
         fastcgi_keep_conn on;
             {{- end }}
         {{- else if eq .Proto "grpc" }}
         grpc_pass {{ trim .Proto }}://{{ trim .Upstream }};
         {{- else }}
         proxy_pass {{ trim .Proto }}://{{ trim .Upstream }}{{ trim .Dest }};
-        set $upstream_keepalive {{ if $keepalive }}true{{ else }}false{{ end }};
+        set $upstream_keepalive {{ if ne $keepalive "disabled" }}true{{ else }}false{{ end }};
         {{- end }}
 
         {{- if (exists (printf "/etc/nginx/htpasswd/%s" .Host)) }}
@@ -315,8 +315,8 @@ upstream {{ .Upstream }} {
     # Fallback entry
     server 127.0.0.1 down;
     {{- end }}
-    {{- $keepalive := first (keys (groupByLabel .Containers "com.github.nginx-proxy.nginx-proxy.keepalive")) }}
-    {{- if $keepalive }}
+    {{- $keepalive := coalesce (first (keys (groupByLabel .Containers "com.github.nginx-proxy.nginx-proxy.keepalive"))) "disabled" }}
+    {{- if ne $keepalive "disabled" }}
     keepalive {{ $keepalive }};
     {{- end }}
 }