Question

How to ping Docker container from another container by name?

Posted on August 27, 2019
Docker Linux Basics Networking Ubuntu
Asked by bitmap

Hi all,

I want to be able to ping or basically access a running docker container from another container by simply using the docker name rather than an IP address. I’ve tried a few guides but I could not get it working. Has anyone been able to get this working?

Thanks a lot!

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Bobby Iliev

Site Moderator

• August 27, 2019

Accepted Answer

Hello,

Yes this now comes more or less out of the box with Docker Networks, so what you need to do is:

Create two containers:

docker run -d --name web1  -p 8001:80 eboraas/apache-php
docker run -d --name web2  -p 8002:80 eboraas/apache-php

Important note: it is very important to explicitly specify a name with --name for your containers otherwise I’ve noticed that it would not work with the random names that Docker assigns to your containers.
Then create a new network:

docker network create myNetwork

After that connect your containers to the network:

docker network connect myNetwork web1
docker network connect myNetwork web2

Check if your containers are part of the new network:

docker network inspect myNetwork

Then test the connection:

docker exec -ti web1 ping web2

Again it is quite important to explicitly specify names for your containers otherwise this would not work. I figured this out after spending a few hours trying to figure it out.

Here’s a quick video demo on how to do the above:

Hope that this helps! Regards, Bobby

Milad Allahyari • September 1, 2023

Use the Same Docker Network: Both containers should be on the same Docker network for this to work. Docker provides default DNS resolution within the same network.
Container Names as Hostnames: By default, Docker sets up DNS entries using container names as hostnames within the same network. For example, if you have two containers named container1 and container2 on the same network, you can ping container2 from container1 using:

ping container2

Docker will resolve container2 to the correct IP address.

Here are the steps to set up this kind of communication:

Create a Docker Network (if not already done): If you haven’t already created a custom Docker network, you can do so with the following command:

docker network create my_network

Replace my_network with the desired network name.
Run Containers on the Same Network: When you run your containers, ensure that you attach them to the same Docker network using the --network flag:

docker run -d --name container1 --network my_network your_image1 
docker run -d --name container2 --network my_network your_image2

Here, container1 and container2 are given as examples of container names. Replace them with your actual container names and use your Docker images.
Test Connectivity: You should now be able to access container2 from container1 using the container name:

docker exec -it container1 ping container2

This should resolve the hostname and successfully ping the other container.
Hostnames in Application Configuration: If you’re using an application inside your containers and you need to specify hostnames in your configuration files, you can use the container names as the hostname.

Keep in mind that DNS resolution using container names is a Docker feature and may not work if you are trying to access containers outside of Docker, or if you have custom DNS configurations that interfere with Docker’s internal DNS resolution. In most standard Docker setups, this approach should work as described.

BigDarkBlueEel • July 15, 2022

create a bridge network and attach the containers to it , then you can ping them by name.