I want to connect 2 containers with each other in a Docker-Swarm

Question

I want to connect two containers with each other ... I start with the creation of an overlay-network mynet :

docker network create -d overlay mynet

After that, I´ve created the first service activemq :

docker service create --name activemq -p 61616:61616 -p 8161:8161  --replicas 1 --network mynet rmohr/activemq

This starts and works perfectly fine, I also can access the WebUI http://localhost:8161/admin/

Now I want to start my serviceTimeService I have the following settings in the container:

docker service create --name timeservice -p 7000:7000  --replicas 1 --network mynet ni920/timeserviceplain:latest

java.naming.provider.url=tcp://localhost:61616
java.naming.user=admin
java.naming.password=admin
io.jexxa.rest.host=0.0.0.0
io.jexxa.rest.port=7000

So it should connect via tcp://localhost:61616 with the ActiveMQ but it doesn't.

Do you guys have any clue what I should try by the way the communication works perfectly in a none Swarm environment or in a Kubernetes-Pod ?

Answer 1

If you want your containers to communicate witch each other, you can use their names then let network driver resolves their ips.

Here is the network driver summary from docker docs:

• User-defined bridge networks are best when you need multiple containers to communicate on the same Docker host.
• Host networks are best when the network stack should not be isolated from the Docker host, but you want other aspects of the container to be isolated.
• Overlay networks are best when you need containers running on different Docker hosts to communicate, or when multiple applications work together using swarm services.
• Macvlan networks are best when you are migrating from a VM setup or need your containers to look like physical hosts on your network, each with a unique MAC address.
• Third-party network plugins allow you to integrate Docker with specialized network stacks.

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In your case, replace localhost with service name activemq .

java.naming.provider.url=tcp://activemq:61616
.
.