Add annotation to add CORS support

ingress/controllers/nginx/controller.go

@@ -43,6 +43,7 @@ import (
  "k8s.io/contrib/ingress/controllers/nginx/nginx"
  "k8s.io/contrib/ingress/controllers/nginx/nginx/auth"
  "k8s.io/contrib/ingress/controllers/nginx/nginx/config"
+ "k8s.io/contrib/ingress/controllers/nginx/nginx/cors"
  "k8s.io/contrib/ingress/controllers/nginx/nginx/healthcheck"
  "k8s.io/contrib/ingress/controllers/nginx/nginx/ingress"
  "k8s.io/contrib/ingress/controllers/nginx/nginx/ipwhitelist"
@@ -717,6 +718,11 @@ func (lbc *loadBalancerController) getUpstreamServers(ngxCfg config.Configuratio
  glog.V(3).Infof("error reading white list annotation in Ingress %v/%v: %v", ing.GetNamespace(), ing.GetName(), err)
  }
 
+ eCORS, err := cors.ParseAnnotations(ing)
+ if err != nil {
+ glog.V(3).Infof("error reading CORS annotation in Ingress %v/%v: %v", ing.GetNamespace(), ing.GetName(), err)
+ }
+
  host := rule.Host
  if host == "" {
  host = defServerName
@@ -749,6 +755,7 @@ func (lbc *loadBalancerController) getUpstreamServers(ngxCfg config.Configuratio
  loc.Redirect = *locRew
  loc.SecureUpstream = secUpstream
  loc.Whitelist = *wl
+ loc.EnableCORS = eCORS
 
  addLoc = false
  continue
@@ -763,7 +770,6 @@ func (lbc *loadBalancerController) getUpstreamServers(ngxCfg config.Configuratio
  }
 
  if addLoc {
-
  server.Locations = append(server.Locations, &ingress.Location{
  Path: nginxPath,
  Upstream: *ups,
@@ -772,6 +778,7 @@ func (lbc *loadBalancerController) getUpstreamServers(ngxCfg config.Configuratio
  Redirect: *locRew,
  SecureUpstream: secUpstream,
  Whitelist: *wl,
+ EnableCORS: eCORS,
  })
  }
  }

ingress/controllers/nginx/nginx.tmpl

@@ -228,6 +228,10 @@ http {
  proxy_set_header Authorization "";
  {{- end }}
 
+ {{ if $location.EnableCORS }}
+ {{ template "CORS" }}
+ {{ end }}
+
  proxy_set_header Host $host;
 
  # Pass Real IP
@@ -374,3 +378,38 @@ stream {
  } 
  {{ end }}
 {{ end }}
+
+{{/* CORS support from https://michielkalkman.com/snippets/nginx-cors-open-configuration.html */}}
+{{ define "CORS" }}
+ if ($request_method = 'OPTIONS') {
+ add_header 'Access-Control-Allow-Origin' '*';
+ #
+ # Om nom nom cookies
+ #
+ add_header 'Access-Control-Allow-Credentials' 'true';
+ add_header 'Access-Control-Allow-Methods' 'GET, POST, OPTIONS';
+ #
+ # Custom headers and headers various browsers *should* be OK with but aren't
+ #
+ add_header 'Access-Control-Allow-Headers' 'DNT,X-CustomHeader,Keep-Alive,User-Agent,X-Requested-With,If-Modified-Since,Cache-Control,Content-Type';
+ #
+ # Tell client that this pre-flight info is valid for 20 days
+ #
+ add_header 'Access-Control-Max-Age' 1728000;
+ add_header 'Content-Type' 'text/plain charset=UTF-8';
+ add_header 'Content-Length' 0;
+ return 204;
+ }
+ if ($request_method = 'POST') {
+ add_header 'Access-Control-Allow-Origin' '*';
+ add_header 'Access-Control-Allow-Credentials' 'true';
+ add_header 'Access-Control-Allow-Methods' 'GET, POST, OPTIONS';
+ add_header 'Access-Control-Allow-Headers' 'DNT,X-CustomHeader,Keep-Alive,User-Agent,X-Requested-With,If-Modified-Since,Cache-Control,Content-Type';
+ }
+ if ($request_method = 'GET') {
+ add_header 'Access-Control-Allow-Origin' '*';
+ add_header 'Access-Control-Allow-Credentials' 'true';
+ add_header 'Access-Control-Allow-Methods' 'GET, POST, OPTIONS';
+ add_header 'Access-Control-Allow-Headers' 'DNT,X-CustomHeader,Keep-Alive,User-Agent,X-Requested-With,If-Modified-Since,Cache-Control,Content-Type';
+ }
+{{ end }}

ingress/controllers/nginx/nginx/cors/main.go

@@ -0,0 +1,50 @@
+/*
+Copyright 2016 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+ http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package cors
+
+import (
+ "errors"
+ "strconv"
+
+ "k8s.io/kubernetes/pkg/apis/extensions"
+)
+
+const (
+ cors = "ingress.kubernetes.io/enable-cors"
+)
+
+type ingAnnotations map[string]string
+
+func (a ingAnnotations) cors() bool {
+ val, ok := a[cors]
+ if ok {
+ if b, err := strconv.ParseBool(val); err == nil {
+ return b
+ }
+ }
+ return false
+}
+
+// ParseAnnotations parses the annotations contained in the ingress
+// rule used to indicate if the location/s should allows CORS
+func ParseAnnotations(ing *extensions.Ingress) (bool, error) {
+ if ing.GetAnnotations() == nil {
+ return false, errors.New("no annotations present")
+ }
+
+ return ingAnnotations(ing.GetAnnotations()).cors(), nil
+}

ingress/controllers/nginx/nginx/ingress/nginx.go

@@ -101,6 +101,7 @@ type Location struct {
  Redirect rewrite.Redirect
  SecureUpstream bool
  Whitelist ipwhitelist.SourceRange
+ EnableCORS bool
 }
 
 // LocationByPath sorts location by path