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Docker - Windows Container Not Resolving Hosts

I have set up two new projects in Visual Studio using the Docker tooling. The first is a asp.net site running against a Linux container. The second is an asp.net site running against a Windows container.

In the former, I can ping hostnames (ex: google.com) and it resolves just fine.

pinging from linux container

However, when running the windows container I cannot do the same thing.

windows network details and pinging from windows container

I am running a custom network so that I can ensure the container starts up on the subnet I want:

docker network create --driver=nat --subnet=192.168.221.0/24

To be clear, I can ping just fine by using an IP but since I want to connect to a database via hostname, this isn't especially helpful during development.

Solution

  • I just figured this out. Requires "switching to windows container" in Docker Desktop.

    1). Follow: https://docs.docker.com/machine/drivers/hyper-v/#example:

    2). Start hyper v (may need to enable): https://learn.microsoft.com/en-us/virtualization/hyper-v-on-windows/quick-start/enable-hyper-v

    3). Then in hyper v create external virtual switch. Select your wifi adapter. (should work with vpn on or off).

    4). reboot.

    5). I used this images as it has to match my local windows windows 10 version:1809

    docker pull mcr.microsoft.com/windows:1809   #takes an hour to finish

    6). Start container and attach to new network.

    docker run -dit --name win1809 mcr.microsoft.com/windows:1809 powershell
docker network ls
docker network connect "John Windows Container Switch" win1809
docker network inspect "John Windows Container Switch"

    shows:

            "Containers": {
            "b8c4ae07761fdf082602f836654013b8d83a717cce9156880a80c7542d855842": {
                "Name": "win1809",
                "EndpointID": "e84652fc93fd1fa2970c3bdcad513d8928fc35823a9f8cf0e638926b6091a60c",
                "MacAddress": "00:15:5d:fb:77:dd",
                "IPv4Address": "",
                "IPv6Address": ""

    7). Connect to container and ping something:

    docker exec -it win1809 powershell
ping www.google.com

Pinging www.google.com [172.217.10.36] with 32 bytes of data:
Reply from 172.217.10.36: bytes=32 time=19ms TTL=118
Reply from 172.217.10.36: bytes=32 time=18ms TTL=118
Reply from 172.217.10.36: bytes=32 time=18ms TTL=118
Reply from 172.217.10.36: bytes=32 time=14ms TTL=118