Recently, we had a customer who came across this error when he tried to start a docker instance.

Docker error "bind: address already in use" happens when another process is using the Docker port.

Here at Ibmi Media, as part of our Server Management Services, we regularly help our Customers to perform related Docker queries.

In this context, we shall look into how to fix this Docker error.

Nature of Docker error "bind: address already in use" ?

While trying to start a docker instance, one of our customers came across the below error:

Error response from daemon: Cannot start container: listen tcp 0.0.0.0:9306: bind: address already in use

The major cause of this error can be another process using the same port.

How to fix Docker error "bind: address already in use" ?

1. To start the container successfully, we kill whatever is using the port.

Initially, we check what uses the port. If it is non-essential at this time, we kill it.

$ sudo lsof -i tcp:8080

In the prompt for the device password, we type it in and press enter. We can replace 8080 with whichever port we want.

Then, we will get a list of currently running processes. Look at the PID of the process. We need it to issue the kill command.

We need to find the process that is obstructing the desired port and ensure it is not of our need.

Then we run the below command to stop the process:

# sudo kill -9 PID

2. Change to another port by modifying the default port in the docker-compose.yml file.

However, if the process that uses the desired port is essential for our setup, we have to change the port for the docker instance.

Ensure to adjust any other project settings linking to this particular port to the new value we select.

Restart the container instance after doing this for changes to take effect.

To start a Docker container using a different port, We suggest the steps below:

We find a free TCP port that we can use (for example, 8086)

Then we delete the existing container:

$ docker rm docker_name

When Docker creates a container, it assigns the ports to it. To change the ports, we delete the existing container first, then re-create it.

Finally, we restart with a different host port number, for example:

$ docker run -d -p 8086:8080 -p 55555:55555 -p:80:80 –shm-size=2g –env username_admin_globalaccesslevel=admin –env username_admin_password=admin –name=docker_name solace/solace-pubsub-standard

3. If for any reason our host reboots.

This issue can happen when the host reboots.

In such a case, we restart our apache server. Stopping the apache2 service in the host can solve it.

$ sudo /etc/init.d/apache2 restart

or

$ sudo apachectl -k restart

4. If Nginx is running globally, it can be the reason too.

$ sudo nginx -s stop

This can happen when the same container runs at some other instance. In that case, docker ps is very helpful.

$ docker-compose down # Stop container on the current directory if there is a docker-compose.yml
$ docker rm -fv $(docker ps -aq) # Remove all containers
$ sudo lsof -i -P -n | grep <port number> # List who is using the port

[Need help with Docker error resolution? We'd be happy to assist. ]