How to access containers by internal IPs 172.x.x.x

[wclr]

How to access containers by internal IP 172.x.x.x from dev machine (with docker for windows installed)? So by default you can not connect to containers.

I found out that it can be achived by adding route manually (you actually need to add routes for each sub-netwrok, I usually do for 17-25):

route /P add 172.17.0.0 MASK 255.255.0.0 10.0.75
route /P add 172.18.0.0 MASK 255.255.0.0 10.0.75
route /P add 172.19.0.0 MASK 255.255.0.0 10.0.75
...

Is is a valid method? Shouldn't it be made possible by default?

[rn]

you should be able to access the containers via localhost. Does that not work?

[wclr]

you should be able to access the containers via localhost.

What do you mean by that? You mean port mapping or what?

I want to reach their IPs, in my case then I use dnsdock to have DNS discovery for containers and access them by pretty dns names (without need of port mapping)

[kallie-b]

So you should be able to access containers from your container host using the container IP. You can use docker inspect <container ID> to get your container's IP address.

Does that answer your question?

[wclr]

@kallie-b ok what should I do after I got IP? I want to ping it by IP. But it won't work from dev machine. I'm asking how to do this.

[kallie-b]

Right, okay--yes, I'm happy to help.

So, can you provide the results that you get when you run docker inspect <container ID>? And let me know which IP address you're trying to use to ping the container--I want to confirm you're using the container's internal IP.

Also, I'm assuming your dev machine is the container host--is that correct? You're not running a VM on your dev machine as the container host, or anything like that?

Could you describe the steps you are taking more specifically (including where each step is executed--in the container, on the container host, or on another, external, host)? Wherever possible, also include any error messages.

[wclr]

I'm assuming your dev machine is the container host

My machine is not a container host, it is a windows 10 dev machine with installed docker for windows, it has only 10.0.75.x interface related to docker, no 172.x.x.x interface to be able to communicate with 172.x.x.x addresses directly. Host machine is linux that runs on Hyper-V, called MobyLinuxVM.

As I've mentioned, this will solve the issue:

route /P add 172.0.0.0 MASK 255.0.0.0 10.0.75.2

If I was using linux (I never used with docker), but I asume my dev machine would be also a docker host, I could access docker internal network 172.x.x.x. directly without any specific manually added routes to route table.

What I want is a comment about this issue from docker team, and if they are going to make integration between windows 10 dev machine and docker internal networks deeper.

[JMesser81]

ping @friism

[wclr]

There seem to be a problem with docker network when such route:

route /P add 172.0.0.0 MASK 255.0.0.0 10.0.75.2

is added

Log is full of events, and growing very fast (log.txt - up to 1GB for a few hours):

15:48:00.469][VpnKit         ][Debug  ] com.docker.slirp.exe: Socket.Datagram.input udp:10.0.75.1:54882-172.26.234.194:51029: creating UDP NAT rule
[15:48:00.471][VpnKit         ][Debug  ] com.docker.slirp.exe: Socket.Datagram.input udp:10.0.75.1:54883-172.26.234.194:51029: creating UDP NAT rule
[15:48:00.473][VpnKit         ][Debug  ] com.docker.slirp.exe: Socket.Datagram.input udp:10.0.75.1:54884-172.26.234.194:51029: creating UDP NAT rule
[15:48:00.475][VpnKit         ][Debug  ] com.docker.slirp.exe: Socket.Datagram.input udp:10.0.75.1:54885-172.26.234.194:51029: creating UDP NAT rule
[15:48:00.476][VpnKit         ][Debug  ] com.docker.slirp.exe: Socket.Datagram.input udp:10.0.75.1:54886-172.26.234.194:51029: creating UDP NAT rule

Here is a log with this case:
https://gist.github.com/whitecolor/4940a8566f2b0211f6864cc11adb69be

Which also effects on the host, CPU usage is going up to 100% some time later

Can you comment on this as well? What is causing those events in the log?

[dgageot]

@whitecolor I'm not sure I understand what you are trying to achieve. Is it a Windows container or a Linux container you are trying to connect to?