feat: Add support for HTTP keep-alive between the proxy and upstream

README.md

@@ -373,6 +373,13 @@ docker run -d -p 80:80 -p 443:443 \
 
 You'll need apache2-utils on the machine where you plan to create the htpasswd file. Follow these [instructions](http://httpd.apache.org/docs/2.2/programs/htpasswd.html)
 
+### Upstream (Backend) Server HTTP Keep-Alive Support
+
+> **Warning**
+> This feature is experimental.  The behavior may change (or the feature may be removed) without warning in a future release, even if the release is not a new major version.  If you use this feature, please provide feedback so we know whether it is working properly and can be promoted to officially supported.
+
+To enable HTTP keep-alive between `nginx-proxy` and a backend server, set the `com.github.nginx-proxy.nginx-proxy.keepalive` label on the server's container to the desired maximum number of idle connections. See the [nginx keepalive documentation](https://nginx.org/en/docs/http/ngx_http_upstream_module.html#keepalive) and the [Docker label documentation](https://docs.docker.com/config/labels-custom-metadata/) for details.
+
 ### Headers
 
 By default, `nginx-proxy` forwards all incoming request headers from the client to the backend server unmodified, with the following exceptions:

nginx.tmpl

@@ -152,6 +152,7 @@
     {{- if exists $override }}
     include {{ $override }};
     {{- else }}
+        {{- $keepalive := first (keys (groupByLabel .Containers "com.github.nginx-proxy.nginx-proxy.keepalive")) }}
     location {{ .Path }} {
         {{- if eq .NetworkTag "internal" }}
         # Only allow traffic from internal clients
@@ -165,10 +166,16 @@
         root {{ trim .VhostRoot }};
         include fastcgi_params;
         fastcgi_pass {{ trim .Upstream }};
+            {{- if $keepalive }}
+        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 }};
+            {{- if $keepalive }}
+        proxy_set_header Connection $proxy_connection_noclose;
+            {{- end }}
         {{- end }}
 
         {{- if (exists (printf "/etc/nginx/htpasswd/%s" .Host)) }}
@@ -208,6 +215,10 @@ 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 {{ $keepalive }};
+    {{- end }}
 }
 {{- end }}
 
@@ -236,6 +247,12 @@ map $http_upgrade $proxy_connection {
     default upgrade;
     '' close;
 }
+map $http_upgrade $proxy_connection_noclose {
+    default upgrade;
+    # By default, nginx sets "Connection: close". Cancel that to allow keepalive
+    # connections between nginx and the upstream server.
+    '' '';
+}
 
 # Apply fix for very long server names
 server_names_hash_bucket_size 128;
@@ -490,7 +507,7 @@ server {
             {{- $upstream = printf "%s-%s" $upstream $sum }}
             {{- $dest = (or (first (groupByKeys $containers "Env.VIRTUAL_DEST")) "") }}
         {{- end }}
-        {{- template "location" (dict "Path" $path "Proto" $proto "Upstream" $upstream "Host" $host "VhostRoot" $vhost_root "Dest" $dest "NetworkTag" $network_tag) }}
+        {{- template "location" (dict "Path" $path "Proto" $proto "Upstream" $upstream "Host" $host "VhostRoot" $vhost_root "Dest" $dest "NetworkTag" $network_tag "Containers" $containers) }}
     {{- end }}
     {{- if and (not (contains $paths "/")) (ne $globals.default_root_response "none")}}
     location / {

test/test_keepalive.py

@@ -0,0 +1,12 @@
+import re
+
+
+def test_keepalive_disabled(docker_compose, nginxproxy):
+    r = nginxproxy.get("http://keepalive-disabled.nginx-proxy.example/headers")
+    assert r.status_code == 200
+    assert re.search(fr'(?m)^(?i:Connection): close$', r.text)
+
+def test_keepalive_enabled(docker_compose, nginxproxy):
+    r = nginxproxy.get("http://keepalive-enabled.nginx-proxy.example/headers")
+    assert r.status_code == 200
+    assert not re.search(fr'(?m)^(?i:Connection):', r.text)

test/test_keepalive.yml

@@ -0,0 +1,23 @@
+keepalive-disabled:
+  image: web
+  expose:
+    - "80"
+  environment:
+    WEB_PORTS: 80
+    VIRTUAL_HOST: keepalive-disabled.nginx-proxy.example
+
+keepalive-enabled:
+  image: web
+  expose:
+    - "80"
+  environment:
+    WEB_PORTS: 80
+    VIRTUAL_HOST: keepalive-enabled.nginx-proxy.example
+  labels:
+    com.github.nginx-proxy.nginx-proxy.keepalive: "64"
+
+
+sut:
+  image: nginxproxy/nginx-proxy:test
+  volumes:
+    - /var/run/docker.sock:/tmp/docker.sock:ro