Question 85487 in Docker Question posted in
The official documentation can be found here.

host.docker.internal vs container name when referencing ip

When defining services in a docker-compose file, when do I use host.docker.internal for the host’s ip and when do I need to use the container’s name?

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2

Answers


  1. 0

    If you want to connect from a container to a service on the host, use host.docker.internal. Be aware, that this special DNS name is only available on Windows and macOS.

    Use the container name for networking between containers.

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  2. 0

    All possible communication flows are illustrated here :

    enter image description here

    (1) : non-containerized process communicates with a container

    (2) : container communicates with another container

    (3) : the opposite direction of (1)

    (1): container must forward port to host, so the non-containerized process can access it

    services:
   c1:
    ...
     ports:
       - hostport:containerport

    (2): container c1 just use the service name (container name – c2) to communicate with c2

    (3): container c2 must Use the private IP of the host(hostname -i).

    For (3), there are couple of points:

    • Host Network range must not overlap with Docker network range, otherwise, Docker router will not throw the request out.

    • Host must not enable firewall that blocks ports used by the non-containerized process.

    • IF you are using Docker For Desktop, host.docker.internal is alias to the Host private IP. then you don’t need to calculate the private IP of the host with hostname -i.

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