I have a MongoDB client in three EC2 instances and I have created a replica set. Last time I had a problem, of space constraint which stopped my mongod process, thereby halting the application and now in an instance couple of days back, some of my tables were gone from database, so I set logging and all to my database just to catch if anything like that happens again. In a fresh incident this morning I was unable to login to my system and that's when I found out that whole database was empty. I checked other SO question like this which suggest setting up a TTL.Which I haven't done at all.
Now how do I debug this situation and do a proper root cause analysis? I can't even find anything in my debug logs as well. The tables just vanished. How do I set up proper logging mechanism and how do I ensure that all my tables are never ever deleted again?
Today I got a mail from Amazon that I was probably running an unsecured version of MongoDB and that may have caused this issue. So who ever is facing this issue please go through the Security Checklist Provided by MongoDB. There are some points that are absolutely necessary in there.
1. Enable Access Control and Enforce Authentication
2. Encrypt Communication
3. Limit Network Exposure
These three are the core and depending upon how many people access your database you can Configure Role-Based Access Control.
These are all the things I have done. Before this incident I had not taken security that seriously but after I was hit by it. I made sure I have all the necessary precautions in place. Hope this helps someone.