ReactiveMongo with Play 2 Framework saying "entire node set is unreachable"

Question

I'm trying to get a Play (2.1) app with ReactiveMongo (0.9) working on the app's test server. However, when our application is run on my dev box, is able to store image metadata just fine, even pointing to the mongo 2.2 install on the mongo test server. Even ran it with "play stage", then run directly with java 1.6.0. However, run the same way, also with Java 1.6.0 on the test server, the app continuously logs this error:

r.c.a.MongoDBSystem - The entire node set is unreachable, is there a network problem? r.c.a.MongoDBSystem - The entire node set is unreachable, is there a network problem? r.c.a.MongoDBSystem - The entire node set is unreachable, is there a network problem?

And not just during initialization... it repeats indefinitely. I've seen this error mentioned elsewhere, but I don't think those solutions apply to this. From the app's test server, I'm able to telnet to port 27017 on the mongo test server successfully. I see both my local install and the test server install of the app log that it's using the same mongodb url.

So based on what I said, I believe I can eliminate:

• Blocked port
• Mongo server down
• Pointing to wrong mongo server
• Mongo version mismatch
• Java version mismatch

I'm going through the reactivemongo source but it seems the error is spewed when the MongoChannels are not set as authenticating or ready state (usable). I'm planning to try remote-debugging to see where it's going wrong, but I'm running out of time on this, so I'm hoping for a troubleshooting tip or two if I can get any.

Thanks!

Answer 1

Alright, figured it out. We're running Casbah/Salat on the same app, for now. There's a mongodb.uri in the config file that gets read in by both. However, ReactiveMongo seems to only work if the database name is included, which according to the mongodb "connection string uri" spec:

http://docs.mongodb.org/manual/reference/connection-string/

... you only need to include the database if you have credentials you need to authenticate with. In our case, we don't have credentials, so Casbah wasn't including the database. I added it in anyway... casbah ignored it safely, and reactivemongo worked. I neglected to do the same in the test config file, so even though it was showing the correct host, it wasn't about to work correctly.

I see how the host url + db name in one string replaces the two fields "mongodb.servers" and "mongodb.db", but it can be confusing if not conforming to mongo's similar spec.