MongoDB operations log (oplog) FAQ
The MongoDB oplog (operations log) is a special capped collection that records all operations that modify the data stored in the database. For more information, see Replica Set Oplog.
Creating a user with read-only access to oplog
To access the MongoDB oplog through oplogUrl, create an oplog user using the IBM Cloud® Databases for MongoDB admin user. The oplog user can set &readPreference=primary so
that reads always happen from the primary.
As the admin user, use a command like:
db.createUser({user: "oplogUser", pwd: "PASSWORD", roles: [{role: "read", db: "local"}]})
Set up Mongodb for open source application use
To set up Databases for MongoDB for use with open-source software, like Meteor.js, configure your MongoDB connection string.
- Create a user that can read the oplog.
- Configure your MongoDB server oplog URL environment variable. For more information, see Meteor's MONGO_OPLOG_URL.