How to check network isolation?

To check network isolation between Docker containers, you can follow these steps:

1. List Networks: First, list all Docker networks to see which networks are available:

   docker network ls

2. Inspect Networks: Inspect the specific networks to see which containers are connected to them. Replace network_name with the name of the network you want to inspect:

   docker network inspect network_name

   This command will show you the containers connected to that network and their IP addresses.

3. Check Container Network Configuration: For each container, you can check its network settings. Replace container_name with the name of your container:

   docker inspect container_name

   Look for the NetworkSettings section to see which networks the container is connected to.

4. Test Connectivity: You can test connectivity between containers by using the ping command. For example, from container1, try to ping container3:

   docker exec container1 ping -c 2 container3

5. Check for Custom Networks: If you are using custom networks, ensure that the containers you want to communicate are on the same custom network. If they are on different networks, you may need to connect them to a common network.

6. Firewall Rules: If you have firewall rules set up on your host machine, ensure that they are not blocking communication between the containers.

By following these steps, you can determine if there is network isolation preventing communication between your Docker containers.