Fix sse for notifications behind nginx reverse proxy (#1650)

scm-webapp/src/main/java/sonia/scm/api/rest/SseHeaderResponseFilter.java

@@ -0,0 +1,59 @@
+/*
+ * MIT License
+ *
+ * Copyright (c) 2020-present Cloudogu GmbH and Contributors
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package sonia.scm.api.rest;
+
+import sonia.scm.sse.SseResponse;
+
+import javax.ws.rs.container.ContainerRequestContext;
+import javax.ws.rs.container.ContainerResponseContext;
+import javax.ws.rs.container.ContainerResponseFilter;
+import javax.ws.rs.core.CacheControl;
+import javax.ws.rs.core.MultivaluedMap;
+import javax.ws.rs.ext.Provider;
+import java.io.IOException;
+
+@Provider
+@SseResponse
+public class SseHeaderResponseFilter implements ContainerResponseFilter {
+
+  @Override
+  public void filter(ContainerRequestContext requestContext, ContainerResponseContext responseContext) throws IOException {
+    MultivaluedMap<String, Object> headers = responseContext.getHeaders();
+    cacheControl(headers);
+    avoidNginxBuffering(headers);
+  }
+
+  private void avoidNginxBuffering(MultivaluedMap<String, Object> headers) {
+    headers.add("X-Accel-Buffering", "no");
+  }
+
+  private void cacheControl(MultivaluedMap<String, Object> headers) {
+    CacheControl cacheControl = new CacheControl();
+    cacheControl.setNoCache(true);
+
+    headers.remove("Cache-Control");
+    headers.add("Cache-Control", cacheControl);
+  }
+}

scm-webapp/src/main/java/sonia/scm/api/v2/CacheControlResponseFilter.java

@@ -21,7 +21,7 @@
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  * SOFTWARE.
  */
-    
+
 package sonia.scm.api.v2;
 
 import org.slf4j.Logger;
@@ -43,12 +43,20 @@ public class CacheControlResponseFilter implements ContainerResponseFilter {
 
   @Override
   public void filter(ContainerRequestContext requestContext, ContainerResponseContext responseContext) {
-    if (!isCacheable(responseContext)) {
+    if (shouldAppendCachingHeader(responseContext)) {
       LOG.trace("add no-cache header to response");
       responseContext.getHeaders().add("Cache-Control", "no-cache");
     }
   }
 
+  private boolean shouldAppendCachingHeader(ContainerResponseContext responseContext) {
+    return !hasAlreadyCacheControl(responseContext) && !isCacheable(responseContext);
+  }
+
+  private boolean hasAlreadyCacheControl(ContainerResponseContext responseContext) {
+    return responseContext.getHeaders().containsKey("Cache-Control");
+  }
+
   private boolean isCacheable(ContainerResponseContext responseContext) {
     return hasLastModifiedDate(responseContext) || hasEntityTag(responseContext);
   }

scm-webapp/src/main/java/sonia/scm/api/v2/resources/NotificationResource.java

@@ -41,6 +41,7 @@ import sonia.scm.security.SessionId;
 import sonia.scm.sse.Channel;
 import sonia.scm.sse.ChannelRegistry;
 import sonia.scm.sse.Registration;
+import sonia.scm.sse.SseResponse;
 import sonia.scm.web.VndMediaType;
 
 import javax.inject.Inject;
@@ -175,6 +176,7 @@ public class NotificationResource {
       mediaType = VndMediaType.ERROR_TYPE,
       schema = @Schema(implementation = ErrorDto.class)
     ))
+  @SseResponse
   public void subscribe(@Context Sse sse, @Context SseEventSink eventSink, @QueryParam(SessionId.PARAMETER) SessionId sessionId) {
     Channel channel = channelRegistry.channel(NotificationChannelId.current());
     channel.register(new Registration(sessionId, sse, eventSink));