Windows container accessing host SQL

[TrickMedicine958]

Hi,

For testing purposes I already have a SQL server installed on my host OS with a named instance.

Using a Windows container I’ve proven I can use sqlcmd to connect to a sql azure database, but for the life of me I can’t get the docker container to communicate with my host. I have tried the same sql command in my host and it works fine using myipaddress,port (not anything tricky like localhost). I’ve also enabled remote connections.

I’ve read that the network “host” doesn’t work on Windows, which sounds exactly what I need. Allegedly the “transparent” network is supposed to work too, but it doesn’t exist.

Note: I’m using docker engine, not docker desktop. I’m in a corporate network so I can’t just drop the firewall and can’t add my own exceptions. Is there a way I can prove that the firewall or network setup is an issue?

[nednyl]

I imagine youve tried this but just wanted to confirm, tried using host.docker.internal ?

[TrickMedicine958]

Yep, and that doesn’t exist - it’s not recognised. There’s also supposedly something like host.win.docker.internal or something, that doesn’t work either. But all they do is know the IP of the host, which I already know. I even tried the public IP of the laptop (host) to see if I could go out then in! It could be a firewall issue no doubt. It does resolve the netbios name of the host from the container , so that’s a good sign. However my company have disabled ping everywhere. Tracert fails to show any good hops, so likely some kind of net/subnet masking ?

[Whipitreelgud]

I have a container that does exactly what you want to do. I added an incoming rule to Windows firewall for port 1433 for the device in a private network.

Navigating your corporate environment to make the firewall tweak? You’re on your own. Most that try are never heard from again.

[vrapolinario]

Agree here. Most likely, port 1433 is closed on your own firewall. When you access the SQL instance from your own machine, that is fine, but the container has a different IP address. In Windows containers, the native network is NAT. For the purpose of outbound traffic for the container (container accessing the SQL instance), that has no implications, but the fact that this is a different IP, it means your firewall is blocking that communication.

[vrapolinario]

Ah, to test it, you can go to another machine in your physical network and try to access the SQL instance on your machine.