Connecting to rabbitmq docker container from service in another container

If you're running a service inside a container, then amqp://guest:guest@localhost won't do you any good; localhost refers to the network namespace of the container...so of course you get an ECONNREFUSED, because there's nothing listening there.

If you want to connect to a service in another container, you need to use the ip address of that container, or a hostname that resolves to the ip address of that container.

If you are running your containers in a user-defined network, then Docker maintains a DNS server that will map container names to addresses. That is, if I first create a network:

docker network create myapp_net

And then start a rabbitmq container in that network:

docker run -d --network myapp_net --hostname rabbitmqhost \   --name rabbitmq -p 15672:15672 -p 5672:5672 rabbitmq:3-management

Then other containers started in that network will be able to use the hostname rabbitmq to connect to that container.

For containers running in the default network (no --network parameter on the command line), you can use the --link option to achieve a similar, though less flexible, effect, as documented here.