Node.js services unable to connect

[Eric Kolotyluk]

I am starting up Mongo via

mongoDbReplicaSet = MongoDbReplicaSet.builder()
  .mongoDockerImageName("mongo:4.4.4")
  .build()

from within my JUnit5/Kotlin framework. I immediately test this using KMongo, and it seems to work fine using the mongoDbReplicaSet.getReplicaSetUrl() string. For example, something like mongodb://localhost:55051/test&readPreference=primary

Then I start my Node.js service via Java's ProcessBuilder and the service seems to run okay. I can send it HTTP requests from my JUnit 5 code, and it responds. However, when I try to connect to MongoDB using the same URI, the Mongo Node driver responds with

MongoServerSelectionError: connect ECONNREFUSED 127.0.0.1:27017
    at Timeout.<anonymous> (/Users/ekolotyluk/dev/crypto/customer-js/node_modules/mongodb/lib/sdam/topology.js:310:38)
    at listOnTimeout (internal/timers.js:554:17)
    at process.processTimers (internal/timers.js:497:7) {
  reason: TopologyDescription {
    type: 'ReplicaSetNoPrimary',
    servers: Map { 'localhost:27017' => [ServerDescription] },
    stale: false,
    compatible: true,
    heartbeatFrequencyMS: 10000,
    localThresholdMS: 15,
    setName: 'docker-rs',
    maxSetVersion: 1,
    maxElectionId: new ObjectId("7fffffff0000000000000001"),
    commonWireVersion: 9,
    logicalSessionTimeoutMinutes: undefined
  }
}

I don't understand why the message is complaining about connect ECONNREFUSED 127.0.0.1:27017 since the URI specifies port 55051. I don't know if the message is from the driver or the server?

When I start MongoDB manually in Docker from our scripts, my Node.js service is able to interact fine with MongoDB.

I also tried using https://www.testcontainers.org/modules/databases/mongodb/ but then the error I get is

MongoServerSelectionError: getaddrinfo ENOTFOUND 3d955cee0480
    at Timeout.<anonymous> (/Users/ekolotyluk/dev/crypto/customer-js/node_modules/mongodb/lib/sdam/topology.js:310:38)
    at listOnTimeout (internal/timers.js:554:17)
    at process.processTimers (internal/timers.js:497:7) {
  reason: TopologyDescription {
    type: 'ReplicaSetNoPrimary',
    servers: Map { '3d955cee0480:27017' => [ServerDescription] },
    stale: false,
    compatible: true,
    heartbeatFrequencyMS: 10000,
    localThresholdMS: 15,
    setName: 'docker-rs',
    maxSetVersion: 1,
    maxElectionId: new ObjectId("7fffffff0000000000000001"),
    commonWireVersion: 9,
    logicalSessionTimeoutMinutes: undefined
  }
}

This seems to be a problem with white-listing, where MongoDB does not like the IP Address my Node.js service is calling from. https://stackoverflow.com/questions/65277035/mongoserverselectionerror-connection-timed-out-with-nodejs-and-express

Any insight on what the problems may be here would be greatly appreciated.

[silaev]

Hi @kolotyluk,
As an experiment, could you try starting up via:

MongoDbReplicaSet.builder()
                 .replicaSetNumber(2)
                 .addArbiter(true)
                 .build()

to force to use a hostname (requires adding host.docker.internal or dockerhost to the OS host file. See Supported features or an article for details) ?
MongoDbReplicaSet#getReplicaSetUrl() will return something like mongodb://dockerhost:55220,dockerhost:55221/test?replicaSet=docker-rs&readPreference=primary in this case