I am building a Node.js application, which reads from a MongoDB cluster. The application uses Mongoose to communicate with Mongo.
I would like to build a functionality, which is able to tell me, what does the mongoose know about the MongoDB replica set real-time (like calling rs.status()), but so far I was not able to find any kind of informations around the internet.
The purpose of this would be to be able to monitor, if something was changed in the replica set, and report it back if needed.
The problem is, I've found so far nothing on the internet in this subject. Does anyone have any idea on how to start it? It would be nice, if I could use the current mongoose connections for this purpose.
You can do this, but you need to be connected to the "admin" database and you will probably want a different connection for this other than what the rest of your application uses. Something like:
var mongoose = require("mongoose");
mongoose.connect(
"mongodb://localhost:27017,localhost:27018,localhost:27019/test");
var conn = mongoose.createConnection(
"mongodb://localhost:27017,localhost:27018,localhost:27019/admin");
conn.on("open",function() {
conn.db.command({"replSetGetStatus":1 },function(err,result) {
console.log( result );
});
});
It is important to wait for the connection to be established as well, hence the "event" callback. Mongoose will internally "queue" it's own methods operations until a connection is made, but this does not apply when grabbing a handle to the native db object and executing methods from that.