Mongoose Failing to connect to MongoDB replicaSet - node.js

Question

I have a replicaSet running in k8s, while trying to connect to the replicaSet from nodejs using mongoose, the connection fails with this logs:
MongooseServerSelectionError: connection timed out
at NativeConnection.Connection.openUri (/app/node_modules/mongoose/lib/connection.js:807:32)
at /app/node_modules/mongoose/lib/index.js:340:10
at promiseOrCallback (/app/node_modules/mongoose/lib/helpers/promiseOrCallback.js:10:12)
at Mongoose._promiseOrCallback (/app/node_modules/mongoose/lib/index.js:1140:10)
at Mongoose.connect (/app/node_modules/mongoose/lib/index.js:339:20)
at /app/src/connect.ts:21:14
at Promise._execute (/app/node_modules/bluebird/js/release/debuggability.js:313:9)
at Promise._resolveFromExecutor (/app/node_modules/bluebird/js/release/promise.js:488:18)
at new Promise (/app/node_modules/bluebird/js/release/promise.js:79:10)
at connect (/app/src/connect.ts:20:10)
at initialiseDatabase (/app/src/connect.ts:8:5)
at Object.<anonymous> (/app/src/mongoose.ts:36:19)
at Module._compile (internal/modules/cjs/loader.js:1085:14)
at Object.Module._extensions..js (internal/modules/cjs/loader.js:1114:10)
at Module.load (internal/modules/cjs/loader.js:950:32)
at Function.Module._load (internal/modules/cjs/loader.js:790:12)
at Module.require (internal/modules/cjs/loader.js:974:19)
at require (internal/modules/cjs/helpers.js:101:18)
at Object.<anonymous> (/app/src/user/operations/find-by-id.ts:1:1)
at Module._compile (internal/modules/cjs/loader.js:1085:14)
at Object.Module._extensions..js (internal/modules/cjs/loader.js:1114:10)
at Module.load (internal/modules/cjs/loader.js:950:32)
at Function.Module._load (internal/modules/cjs/loader.js:790:12)
at Module.require (internal/modules/cjs/loader.js:974:19)
at require (internal/modules/cjs/helpers.js:101:18)
at Object.<anonymous> (/app/src/middleware/authenticate.ts:7:1)
at Module._compile (internal/modules/cjs/loader.js:1085:14)
at Object.Module._extensions..js (internal/modules/cjs/loader.js:1114:10)
at Module.load (internal/modules/cjs/loader.js:950:32)
at Function.Module._load (internal/modules/cjs/loader.js:790:12)
at Module.require (internal/modules/cjs/loader.js:974:19)
at require (internal/modules/cjs/helpers.js:101:18)
at Object.<anonymous> (/app/src/app.ts:8:1)
at Module._compile (internal/modules/cjs/loader.js:1085:14)
at Object.Module._extensions..js (internal/modules/cjs/loader.js:1114:10)
at Module.load (internal/modules/cjs/loader.js:950:32)
at Function.Module._load (internal/modules/cjs/loader.js:790:12)
at Function.executeUserEntryPoint [as runMain] (internal/modules/run_main.js:75:12)
at internal/main/run_main_module.js:17:47 {
reason: TopologyDescription {
type: 'ReplicaSetNoPrimary',
servers: Map(3) {
'mongodb-0.mongodb-headless.staging.svc.cluster.local:27017' => [ServerDescription],
'mongodb-1.mongodb-headless.staging.svc.cluster.local:27017' => [ServerDescription],
'mongodb-2.mongodb-headless.staging.svc.cluster.local:27017' => [ServerDescription]
},
And this is my connection string:
mongodb://username:pw#mongodb-0.mongodb-headless.staging.svc.cluster.local:27017,mongodb-1.mongodb-headless.staging.svc.cluster.local:27017,mongodb-2.mongodb-headless.staging.svc.cluster.local:27017/labxpert?authSource=admin&serverSelectionTimeoutMS=50000&replicaSet=rs0
When I test the connection with the mongo Shell, it works just fine.
What could be causing the MongooseServerSelectionError: connection timed out.

Answer 1

For anyone who may face this problem with mongoose v6+ and nodejs and white listing your ip has not solved it or changing from localhost to 127.0.0.1.
Solution
Set the following options for the mongoose client connection options:
mongoose.connect(url, {
maxIdleTimeMS: 80000,
serverSelectionTimeoutMS: 80000,
socketTimeoutMS: 0,
connectTimeoutMS: 0
}
These options stop the mongoose client from timining out the connection before it selects a primary from the DB cluster.
Please remember to set any other options relevant to your setup like if you are running a cluster, make sure to set the replicaSet option or if you have authentication enabled, set the authSource option or the database you are connecting to dbName.
Some of these options can be set in the connection string.
The full list of options can be found here: https://mongodb.github.io/node-mongodb-native/4.2/interfaces/MongoClientOptions.html#authSource