Set ReadPreference for mongodb in WAR file

[selvaganesh]

I need to set the readpreference of mongodb as primaryPreferred in web.xml. How to do it?

[Opkar_Gill]

With standalone AEM instances there is no web.xml

Which reference did you read about setting readpreference? This seems like a MongoDB setting rather than an AEM setting.

[selvaganesh]

This is for the war file. I referred http://jackrabbit.apache.org/oak/docs/nodestore/documentmk.html for details. But I am not able to set the read preference. It has to be set from AEM server.

[Lokesh_Shivalingaiah · Accepted solution]

So in the same document, it has mentioned to set that as part of configuration. So you can mention as part of your Mongo URI configration in AEM as below

via Configuration

In this mode the config is specified as part of the Mongo URI (See configuration). So if a user wants that reads from secondaries should prefer secondary with tag dc:ny,rack:1otherwise they go to other secondary then he can specify that via following mongouri

mongodb://example1.com,example2.com,example3.com/?readPreference=secondary&readPreferenceTags=dc:ny,rack:1&readPreferenceTags=dc:ny&readPreferenceTags= 

[selvaganesh]

This is not working. I am setting the readPreference as primaryPreferred. When I shutdown the primary db, AEM always tries to connect to primary.  I am getting the below error. As you see below the readPreference is not modifed even though I pass this parameter in web.xml 

18.08.2015 21:09:32.707 *WARN* [DocumentNodeStore lease update thread] org.apache.jackrabbit.oak.plugins.document.DocumentNodeStore Background operation failed: org.apache.jackrabbit.oak.plugins.document.DocumentStoreException: Timed out after 10000 ms while waiting for a server that matches {serverSelectors=[ReadPreferenceServerSelector{readPreference=primary}, LatencyMinimizingServerSelector{acceptableLatencyDifference=15 ms}]}. Client view of cluster state is {type=ReplicaSet, servers=[{address=local:17017, type=ReplicaSetArbiter, averageLatency=1.9 ms, state=Connected}, {address=local:27017, type=ReplicaSetSecondary, averageLatency=2.1 ms, state=Connected}, {address=1local:27017, type=Unknown, state=Connecting, exception={com.mongodb.MongoException$Network: Exception opening the socket}, caused by {java.net.ConnectException: Connection refused}}]