From inside of a Docker container, how do I connect to the local

ghz 8months ago ⋅ 80 views

From inside of a Docker container, how do I connect to the localhost of the machine?

I have a Nginx running inside a docker container. I have a MySql running on the host system. I want to connect to the MySql from within my container. MySql is only binding to the localhost device.

Is there any way to connect to this MySql or any other program on localhost from within this docker container?

This question is different from "How to get the IP address of the docker host from inside a docker container" due to the fact that the IP address of the docker host could be the public IP or the private IP in the network which may or may not be reachable from within the docker container (I mean public IP if hosted at AWS or something). Even if you have the IP address of the docker host it does not mean you can connect to docker host from within the container given that IP address as your Docker network may be overlay, host, bridge, macvlan, none etc which restricts the reachability of that IP address.

Answers

If your MySQL database is only binding to the localhost interface (127.0.0.1), it's not directly accessible from within your Docker container, as containers have their own isolated network stack. However, there are several ways you can enable communication between your Docker container and the MySQL database running on the host system:

  1. Bind MySQL to a specific network interface: Modify the MySQL configuration to bind to the IP address of the network interface that Docker is using on the host system (e.g., the IP address of the bridge network interface). This way, MySQL will listen for connections on that interface and will be accessible from within the Docker container.

  2. Use Docker host network: Run your Docker container with the --network host option, which allows the container to share the network namespace with the Docker host. This means the container will use the same network interfaces as the host, allowing it to communicate with services running on the host, including MySQL.

docker run --network host your_image_name
  1. Use Docker bridge network with host networking: Create a Docker bridge network with the --attachable option, which allows you to attach containers to it later. Then, run your container with both the Docker bridge network and host network, allowing it to communicate with both containers on the Docker bridge network and services on the host.
docker network create --driver bridge --attachable my_bridge_network

docker run --network my_bridge_network --network host your_image_name

  1. Expose MySQL on a public IP or specific interface: If you're running MySQL on a cloud provider like AWS, you can configure MySQL to bind to a public IP or a specific network interface that's accessible from within the Docker container.

  2. Use port forwarding: Set up port forwarding on your host system to forward connections to MySQL on localhost to a specific port that's accessible from within the Docker container. This can be done using tools like iptables or platform-specific port forwarding configurations.

Choose the method that best fits your requirements and security considerations. Ensure to properly secure your MySQL database if you're exposing it to external networks or Docker containers.

#docker