com.mongodb.MongoSocketOpenException: when connecting to mongodb docker container

I have an sbt project which has mongodb code i am making a custom image of this sbt project and using mongodb:2.6.11 public docker image https://hub.docker.com/_/mongo

here is the docker file of my sbt project

FROM hseeberger/scala-sbt:11.0.2_2.12.8_1.2.8 as stripecommon

MAINTAINER sara <[email protected]>

WORKDIR /myproject

ADD myprojectcode .

CMD ["sbt","reload","clean","compile","run"]

and here is the dockerfile of the mongodb image mongodb:2.6.11 https://github.com/ky13R/mongo-2.6.11-docker-image/blob/master/Dockerfile

here is how i am running my containers

docker create network mynetwork

to start mongodb container

docker run -p 27017 --network mynetwork mongo:2.6.11

to start my project container

docker run --network mynetwork myproject:v1

and my project is unable to connect to the mongodb server here is the exception log

com.mongodb.MongoSocketOpenException: Exception opening socket
    at com.mongodb.connection.SocketStream.open(SocketStream.java:63)
    at com.mongodb.connection.InternalStreamConnection.open(InternalStreamConnection.java:114)
    at com.mongodb.connection.DefaultServerMonitor$ServerMonitorRunnable.run(DefaultServerMonitor.java:128)
    at java.base/java.lang.Thread.run(Thread.java:834)
Caused by: java.net.ConnectException: Connection refused (Connection refused)
    at java.base/java.net.PlainSocketImpl.socketConnect(Native Method)
    at java.base/java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:399)
    at java.base/java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:242)
    at java.base/java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:224)
    at java.base/java.net.SocksSocketImpl.connect(SocksSocketImpl.java:403)
    at java.base/java.net.Socket.connect(Socket.java:591)
    at com.mongodb.connection.SocketStreamHelper.initialize(SocketStreamHelper.java:50)
    at com.mongodb.connection.SocketStream.open(SocketStream.java:58)
    ... 3 common frames omitted

i have followed this tutorial to connect to mongodb server https://dzone.com/articles/using-docker-to-shove-an-existing-application-into what i am doing wrong here?

the code for connecting to mongo server is

private val DATABASE:String   = config.getString("db.dbname")
  private val SERVER:ServerAddress = {
      val hostName=config.getString("db.hostname")
      val port=config.getString("db.port").toInt
    new ServerAddress(hostName,port)
      } 
  val connectionMongo = MongoClient(SERVER)
  log.debug("mongo connection created "+connectionMongo)
  def collectionMongo(name:String) = connectionMongo(DATABASE)(name)
  log.debug("getting collection from mongodb")
}

and here is the config file

db.url="mongodb://Localhost:27017"
db.hostname="Localhost"
db.dbname=testdb
db.port=27017

Solution

The Problem is that you are using localhost for db.url and db.hostname. Localhost referred to the Docker Container of your application is inside the container, not your host machine. What you can do is starting the MongoDB container with a concrete name, like this:

docker run -p 27017 --name mongodb --network mynetwork mongo:2.6.11

And use the following config within your application:

db.url="mongodb://mongodb:27017"
db.hostname="mongodb"
db.dbname=testdb
db.port=27017

Within your docker network (mynetwork), the database container is reachable by it's container name (here mongodb)

Hope I can help.

Edit:

Another (easier) way to solve this is to "link" the containers. By doing so, you don't need to create a network beforehand.

How to do it?

Start your mongo database:

docker run -p 27017 --name mongodb mongo:2.6.11

Start your application and link to the mongo-db container, previously created:

docker run --link mongodb myproject:v1