ASP.NET Core with Docker support: Connection refused

Question

I have a ASP .NET Core (v2.0) app with Docker support. And I want to start a Oracle Database when starting my app. This is how my docker-compose file looks like:

version: '3'

services:
  devarttestapp:
    image: devarttestapp
    build:
      context: ./DevartTestApp
      dockerfile: Dockerfile

  oracledb:
    image: sath89/oracle-12c
    ports: 
      - "1521:1521"

I use Devart data provider dotConnect for Oracle.

var conn = new Devart.Data.Oracle.OracleConnection();
conn.ConnectionString = Environment.GetEnvironmentVariable("ORACLE_CONNECTION_STRING");
try
{
    conn.Open();
}
catch (Exception e)
{
    Console.WriteLine(e);
    throw;
}

But when I try to connect to the database of the created Oracle DB container I get following exception:

System.Net.Internals.SocketExceptionFactory+ExtendedSocketException (Connection refused 127.0.0.1:1521)

I also tried to include the depends_on as well as the networks option in my docker-compose file with the same results.

What could be the cause of this exception?
And how do I solve this problem?

please check if it helps oracledebugging.com/2011/09/oracle-database-10g-debugging.html — psaraj12
The database is not the problem since I can connect to it. Only the web app running in a Docker container seems to have problems to connect to the database in the other Docker container. — Palmi

TJ Zimmerman TJ Zimmerman · Accepted Answer · 2017-08-16T17:54:03

From within the container, can you send me the output of this command?

apt-get update && apt-get install nmap -y && nmap -p 1521 localhost

If you are unfamiliar with how to access bash inside the container, this is how:

Find your container ID or name: docker ps Connect to BASH: docker exec -it >containerID< /bin/bash

I have a feeling that his issue pertains to Oracle rather than Docker as your docker-compose file looks correct. Perhaps the listener hasn't been enabled. I would also appreciate the output of: lsnrctl status if nmap says that the port is not open.

https://docs.oracle.com/cd/E11882_01/network.112/e41945/listenercfg.htm#NETAG010

ASP.NET Core with Docker support: Connection refused

3 Answers