Continuous Delivery with Docker and Jenkins

Publishing ports

Docker services, similar to the containers, have a port forwarding mechanism. We use it by adding the -p <host_port>:<container:port> parameter. Here's what starting a service could look like:

$ docker service create --replicas 1 --publish 8080:8080 --name tomcat tomcat

Now, we can open a browser and see the Tomcat's main page under the address http://192.168.0.143:8080/.

The application is available on the manager host that acts as a load balancer and distributes requests to worker nodes. What may sound a little less intuitive is the fact that we can access Tomcat using the IP address of any worker, for example, if worker nodes are available under 192.168.0.166 and 192.168.0.115, we can access the same running container ...