feat: configure setting real IP with header from other pods

assets/default.conf

@@ -205,6 +205,10 @@ $(( else ))
     etag 'off';
 $(( end ))
 
+$((- if .SetRealIPFrom ))
+    set_real_ip_from $(( .SetRealIPFrom ));
+$(( end ))
+
     # (Security) Don't serve dotfiles, except .well-known/, which is needed by
     # LetsEncrypt
     location ~ /\.(?!well-known) {

build.go

@@ -38,6 +38,8 @@ func Build(logger scribe.Emitter) packit.BuildFunc {
 					// https://github.com/paketo-buildpacks/nginx/issues/447
 					LastModifiedValue: time.Now().UTC().Format(http.TimeFormat),
 					ETag:              false,
+					// allow from Pod CIDR
+					SetRealIPFrom: "10.42.0.0/16",
 					Configuration: nginx.Configuration{
 						NGINXConfLocation: nginxConf,
 						WebServerRoot:     webRoot,

default_config_generator.go

@@ -25,6 +25,7 @@ type DefaultConfigGenerator struct {
 type Configuration struct {
 	LastModifiedValue string
 	ETag              bool
+	SetRealIPFrom     string
 	nginx.Configuration
 }