Add nginx 500 and 502 servers

Author: Kate Osborn

deploy/manifests/nginx-gateway.yaml

@@ -82,6 +82,8 @@ spec:
       volumes:
       - name: nginx-config
         emptyDir: { }
+      - name: var-lib-nginx
+        emptyDir: { }
       - name: njs-modules
         configMap:
           name: njs-modules
@@ -92,6 +94,8 @@ spec:
         volumeMounts:
         - name: nginx-config
           mountPath: /etc/nginx
+        - name: var-lib-nginx
+          mountPath: /var/lib/nginx
       containers:
       - image: ghcr.io/nginxinc/nginx-kubernetes-gateway:edge
         imagePullPolicy: Always
@@ -118,5 +122,7 @@ spec:
         volumeMounts:
         - name: nginx-config
           mountPath: /etc/nginx
+        - name: var-lib-nginx
+          mountPath: /var/lib/nginx
         - name: njs-modules
           mountPath: /usr/lib/nginx/modules/njs

internal/nginx/config/template/servers.go

@@ -53,4 +53,17 @@ server {
 }
 	{{ end }}
 {{ end }}
+server {
+    listen unix:/var/lib/nginx/nginx-502-server.sock;
+    access_log off;
+
+    return 502;
+}
+
+server {
+    listen unix:/var/lib/nginx/nginx-500-server.sock;
+    access_log off;
+    
+    return 500;
+}
 `

internal/nginx/config/upstreams.go

@@ -11,6 +11,8 @@ import (
 const (
 	// nginx502Server is used as a backend for services that cannot be resolved (have no IP address).
 	nginx502Server = "unix:/var/lib/nginx/nginx-502-server.sock"
+	// nginx500Server is used as a server for the invalid backend ref upstream.
+	nginx500Server = "unix:/var/lib/nginx/nginx-500-server.sock"
 	// invalidBackendRef is used as an upstream name for invalid backend references.
 	invalidBackendRef = "invalid-backend-ref"
 )
@@ -65,7 +67,7 @@ func createInvalidBackendRefUpstream() http.Upstream {
 		Name: invalidBackendRef,
 		Servers: []http.UpstreamServer{
 			{
-				Address: nginx502Server,
+				Address: nginx500Server,
 			},
 		},
 	}

internal/nginx/config/upstreams_test.go

@@ -128,7 +128,7 @@ func TestCreateUpstreams(t *testing.T) {
 			Name: invalidBackendRef,
 			Servers: []http.UpstreamServer{
 				{
-					Address: nginx502Server,
+					Address: nginx500Server,
 				},
 			},
 		},