Docker networks: How to get container1 to communicate with server in container2

Jacob Steiner 0
Viewed 36

I have 2 containers on a docker bridge network. One of them has an apache server that i am using as a reverse proxy to forward user to server on another container. The other container contains a server that is listening on port 8081. I have verified both containers are on the same network and when i log into an interactive shell on each container i tested successfully that i am able to ping the other container. The problem is, is that when i am logged into the container with the apache server, i am not able to ping the actual server in the other container.

the ip address of container with server is 172.17.0.2

How i create the docker network

docker network create -d bridge jakeypoo

How i start the containers

docker container run -p 8080:8080 --network="jakeypoo" --
name="idpproxy" idpproxy:latest

docker run -p 8081:8080 --name geoserver --network="jakeypoo" geoserver:1.1.0

wouldn't the uri to reach out to the server be

http://172.17.0.2:8081/

?

PS: I am sure more information will be needed and i am new to stack overflow and will happily answer any other questions i can.

bridge networking apache server docker
2 Answers

Since you started the two containers on the same --network, you can use their --name as hostnames to talk to each other. If the service inside the second container is listening on port 8080, use that port number. Remappings with docker run -p options are ignored, and you don't need a -p option to communicate between containers.

In your Apache config, you'd set up something like

ProxyPass "/" "http://geoserver:8080/"
ProxyPassReverse "/" "http://geoserver:8080/"

It's not usually useful to look up the container-private IP addresses: they will change whenever you recreate the container, and in most environments they can't be used outside of Docker (and inside of Docker the name-based lookup is easier).

(Were you to run this under Docker Compose, it automatically creates a network for you, and each service is accessible under its Compose service name. You do not need to manually set networks: or container_name: options, and like the docker run -p option, Compose ports: are not required and are ignored if present. Networking in Compose in the Docker documentation describes this further.)

David Maze0

Most probably this can be the reason.

when you log into one of the container that container do not know anything about the other container network. when you ping, that container think you are try to ping a service inside that container.

Try to use docker compose if you can use it in your context. Refer this link: https://docs.docker.com/compose/

YJR0
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