Unable to access CouchbaseCluster on Google App Engine

Hi!

I’m unable to access CouchbaseCluster on Google App Engine. Here’s the code:

Cluster cluster = CouchbaseCluster.create(Collections.singletonList(“http://”)); // MyServlet.java; line: 40

Stacktrace:

Uncaught exception from servlet java.lang.NoClassDefFoundError: java.nio.channels.spi.SelectorProvider is a restricted class. Please see the Google App Engine developer’s guide for more details.
at com.google.apphosting.runtime.security.shared.stub.java.nio.channels.spi.SelectorProvider.(SelectorProvider.java)
at com.couchbase.client.deps.io.netty.channel.nio.NioEventLoopGroup.(NioEventLoopGroup.java:52)
at com.couchbase.client.core.env.DefaultCoreEnvironment.(DefaultCoreEnvironment.java:262)
at com.couchbase.client.java.env.DefaultCouchbaseEnvironment.(DefaultCouchbaseEnvironment.java:124)
at com.couchbase.client.java.env.DefaultCouchbaseEnvironment.(DefaultCouchbaseEnvironment.java:55)
at com.couchbase.client.java.env.DefaultCouchbaseEnvironment$Builder.build(DefaultCouchbaseEnvironment.java:472)
at com.couchbase.client.java.env.DefaultCouchbaseEnvironment.create(DefaultCouchbaseEnvironment.java:158)
at com.couchbase.client.java.CouchbaseCluster.create(CouchbaseCluster.java:164)
at ben.tests.couch8.backend.MyServlet.doPost(MyServlet.java:40)

The class java.nio.channels.spi.SelectorProvider is not white listed: https://cloud.google.com/appengine/docs/java/jrewhitelist

Is there a workaround? Shall I try another cloud provider? Suggestions?

Ultimately I was trying to create a new user or log the user in. I followed these two blog posts: blog. couchbase. com/2015/september/adding-user-sign-up-to-your-android-app-with-node.js-and-couchbase-mobile and blog. couchbase. com/traveling-with-couchbase-using-the-java-sdk

Regards,
Ben

Cluster cluster = CouchbaseCluster.create(Collections.singletonList(“http://MY-IP”)); // MyServlet.java; line: 40

blog posts:

http://blog.couchbase.com/2015/september/adding-user-sign-up-to-your-android-app-with-node.js-and-couchbase-mobile
http://blog.couchbase.com/traveling-with-couchbase-using-the-java-sdk

Regards,
Ben

@benjamin_glatzeder can you please just try the ip address without http? CouchbaseCluster.create(“MY-IP”) should work just fine.

If the problem persists, please share logs with TRACE logging enabled!

Hi @daschl

this is all of the code:

@Override
public void doPost(HttpServletRequest req, HttpServletResponse resp) throws IOException {
    Cluster cluster = CouchbaseCluster.create("MY-IP");
    String username = req.getParameter("username");
    String password = req.getParameter("password");
    resp.getWriter().println("username = " + username);
    resp.getWriter().println("password = " + password);
}

If I delete this line: Cluster cluster = CouchbaseCluster.create("MY-IP"); then there is no error and username and password are printed.
I guess that the “MY-IP”-address is correct. I can point my browser to “MY-IP”:4984 and receive a valid output: {"couchdb":"Welcome","vendor":{"name":"Couchbase Sync Gateway","version":1},"version":"Couchbase Sync Gateway/1.1.1(10;2fff9eb)"}

TRACE Logging
I searched for Google App engine and Trace Logging. This seemed to be for performance measurements. I can only provide you the two traces below. Sorry!

This is the full stack trace:
Warning:

java.lang.NoClassDefFoundError: Could not initialize class     
com.google.apphosting.runtime.security.shared.stub.java.nio.channels.spi.SelectorProvider 
at com.couchbase.client.deps.io.netty.channel.nio.NioEventLoopGroup.<init>(NioEventLoopGroup.java:52) 
at com.couchbase.client.core.env.DefaultCoreEnvironment.<init>(DefaultCoreEnvironment.java:262) 
at com.couchbase.client.java.env.DefaultCouchbaseEnvironment.<init>(DefaultCouchbaseEnvironment.java:124) 
at com.couchbase.client.java.env.DefaultCouchbaseEnvironment.<init>(DefaultCouchbaseEnvironment.java:55) 
at com.couchbase.client.java.env.DefaultCouchbaseEnvironment$Builder.build(DefaultCouchbaseEnvironment.java:472) 
at com.couchbase.client.java.env.DefaultCouchbaseEnvironment.create(DefaultCouchbaseEnvironment.java:158) 
at com.couchbase.client.java.CouchbaseCluster.create(CouchbaseCluster.java:164) 
at com.couchbase.client.java.CouchbaseCluster.create(CouchbaseCluster.java:151) 
at ben.tests.couch8.backend.MyServlet.doPost(MyServlet.java:40) 
at javax.servlet.http.HttpServlet.service(HttpServlet.java:637) 
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717) 
at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:511) 
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1166) 
at com.google.apphosting.utils.servlet.ParseBlobUploadFilter.doFilter(ParseBlobUploadFilter.java:125) 
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157) 
at com.google.apphosting.runtime.jetty.SaveSessionFilter.doFilter(SaveSessionFilter.java:37) 
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157) 
at com.google.apphosting.utils.servlet.JdbcMySqlConnectionCleanupFilter.doFilter(JdbcMySqlConnectionCleanupFilter.java:60) 
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157) 
at com.google.apphosting.utils.servlet.TransactionCleanupFilter.doFilter(TransactionCleanupFilter.java:43) 
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157) 
at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:388) 
at org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:216) 
at org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:182) 
at org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:765) 
at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:418) 
at com.google.apphosting.runtime.jetty.AppVersionHandlerMap.handle(AppVersionHandlerMap.java:260) 
at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152) 
at org.mortbay.jetty.Server.handle(Server.java:326) 
at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:542) 
at org.mortbay.jetty.HttpConnection$RequestHandler.headerComplete(HttpConnection.java:923) 
at com.google.apphosting.runtime.jetty.RpcRequestParser.parseAvailable(RpcRequestParser.java:78) 
at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:404) 
at com.google.apphosting.runtime.jetty.JettyServletEngineAdapter.serviceRequest(JettyServletEngineAdapter.java:148) 
at com.google.apphosting.runtime.JavaRuntime$RequestRunnable.run(JavaRuntime.java:469) 
at com.google.tracing.TraceContext$TraceContextRunnable.runInContext(TraceContext.java:437) 
at com.google.tracing.TraceContext$TraceContextRunnable$1.run(TraceContext.java:444) 
at com.google.tracing.CurrentContext.runInContext(CurrentContext.java:256) 
at com.google.tracing.TraceContext$AbstractTraceContextCallback.runInInheritedContextNoUnref(TraceContext.java:308) 
at com.google.tracing.TraceContext$AbstractTraceContextCallback.runInInheritedContext(TraceContext.java:300) 
at com.google.tracing.TraceContext$TraceContextRunnable.run(TraceContext.java:441) 
at com.google.apphosting.runtime.ThreadGroupPool$PoolEntry.run(ThreadGroupPool.java:235) 
at java.lang.Thread.run(Thread.java:745)

Fatal:

java.lang.NoClassDefFoundError: Could not initialize class com.google.apphosting.runtime.security.shared.stub.java.nio.channels.spi.SelectorProvider 
at com.couchbase.client.deps.io.netty.channel.nio.NioEventLoopGroup.<init>(NioEventLoopGroup.java:52) 
at com.couchbase.client.core.env.DefaultCoreEnvironment.<init>(DefaultCoreEnvironment.java:262) 
at com.couchbase.client.java.env.DefaultCouchbaseEnvironment.<init>(DefaultCouchbaseEnvironment.java:124) 
at com.couchbase.client.java.env.DefaultCouchbaseEnvironment.<init>(DefaultCouchbaseEnvironment.java:55) 
at com.couchbase.client.java.env.DefaultCouchbaseEnvironment$Builder.build(DefaultCouchbaseEnvironment.java:472) 
at com.couchbase.client.java.env.DefaultCouchbaseEnvironment.create(DefaultCouchbaseEnvironment.java:158) 
at com.couchbase.client.java.CouchbaseCluster.create(CouchbaseCluster.java:164) 
at com.couchbase.client.java.CouchbaseCluster.create(CouchbaseCluster.java:151) 
at ben.tests.couch8.backend.MyServlet.doPost(MyServlet.java:40) 
at javax.servlet.http.HttpServlet.service(HttpServlet.java:637) 
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717) 
at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:511) 
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1166) 
at com.google.apphosting.utils.servlet.ParseBlobUploadFilter.doFilter(ParseBlobUploadFilter.java:125) 
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157) 
at com.google.apphosting.runtime.jetty.SaveSessionFilter.doFilter(SaveSessionFilter.java:37) 
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157) 
at com.google.apphosting.utils.servlet.JdbcMySqlConnectionCleanupFilter.doFilter(JdbcMySqlConnectionCleanupFilter.java:60) 
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157) 
at com.google.apphosting.utils.servlet.TransactionCleanupFilter.doFilter(TransactionCleanupFilter.java:43) 
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157) 
at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:388) 
at org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:216) 
at org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:182) 
at org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:765) 
at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:418) 
at com.google.apphosting.runtime.jetty.AppVersionHandlerMap.handle(AppVersionHandlerMap.java:260) 
at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152) 
at org.mortbay.jetty.Server.handle(Server.java:326) 
at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:542) 
at org.mortbay.jetty.HttpConnection$RequestHandler.headerComplete(HttpConnection.java:923) 
at com.google.apphosting.runtime.jetty.RpcRequestParser.parseAvailable(RpcRequestParser.java:78) 
at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:404) 
at com.google.apphosting.runtime.jetty.JettyServletEngineAdapter.serviceRequest(JettyServletEngineAdapter.java:148) 
at com.google.apphosting.runtime.JavaRuntime$RequestRunnable.run(JavaRuntime.java:469) 
at com.google.tracing.TraceContext$TraceContextRunnable.runInContext(TraceContext.java:437) 
at com.google.tracing.TraceContext$TraceContextRunnable$1.run(TraceContext.java:444) 
at com.google.tracing.CurrentContext.runInContext(CurrentContext.java:256) 
at com.google.tracing.TraceContext$AbstractTraceContextCallback.runInInheritedContextNoUnref(TraceContext.java:308) 
at com.google.tracing.TraceContext$AbstractTraceContextCallback.runInInheritedContext(TraceContext.java:300) 
at com.google.tracing.TraceContext$TraceContextRunnable.run(TraceContext.java:441) 
at com.google.apphosting.runtime.ThreadGroupPool$PoolEntry.run(ThreadGroupPool.java:235) 
at java.lang.Thread.run(Thread.java:745)

Thanks,
Ben

Code runs on local server. Exception is thrown because of Google App Engine security restrictions. I’ll close this thread.

Thanks,
Ben

Interesting. Is there a change we should make? It seems odd that classloading NIO is how a security restriction would fail. Any pointers to authoritative docs?

All I know is this:

I posted my findings at Google App Engine’s forum: https://groups.google.com/d/topic/google-appengine/bvhyFulN5ss/discussion

Regards,
Ben

It says NIO is not available apparently - one thing we could try is using OIO in netty (uses blocking io) but we never tested that. All you need to do is pass in a OioEventLoopGroup into the environment - let me know if that works.

But the person in the post also said we’d have trouble opening threads which if true seems like a blocking issue for using any kind of networking lib on GAE?