docker.for.win.localhost does not enable cntlm proxy listening on host

[alanmpitts]

Expected behavior

• Install and properly configure cntlm proxy listening on the standard port and gateway enabled.
• Install Docker 4 Windows on a Windows 10 Enterprise Version 1607 Build 14393.1480
• Go to Docker 4 Windows manual proxy settings and enter http://docker.for.win.localhost:3128 for both the http and https proxy settings.
• able to login to docker hub using "docker login"

Actual behavior

With http://docker.for.windows.localhost:3128 set for the docker proxy. I get the following when I issue the command "docker login"

Error response from daemon: Get https://registry-1.docker.io/v2/: proxyconnect tcp: dial tcp: lookup docker.for.win.10.0
.75.1 on 192.168.65.1:53: no such host

Information

I have noticed that the docker engine has translated the proxy settings to http://docker.for.windows.10.0.75.1:3128

Here is docker info:

Containers: 0
 Running: 0
 Paused: 0
 Stopped: 0
Images: 0
Server Version: 17.06.2-ce
Storage Driver: overlay2
 Backing Filesystem: extfs
 Supports d_type: true
 Native Overlay Diff: true
Logging Driver: json-file
Cgroup Driver: cgroupfs
Plugins:
 Volume: local
 Network: bridge host ipvlan macvlan null overlay
 Log: awslogs fluentd gcplogs gelf journald json-file logentries splunk syslog
Swarm: inactive
Runtimes: runc
Default Runtime: runc
Init Binary: docker-init
containerd version: 6e23458c129b551d5c9871e5174f6b1b7f6d1170
runc version: 810190ceaa507aa2727d7ae6f4790c76ec150bd2
init version: 949e6fa
Security Options:
 seccomp
  Profile: default
Kernel Version: 4.9.41-moby
Operating System: Alpine Linux v3.5
OSType: linux
Architecture: x86_64
CPUs: 2
Total Memory: 1.934GiB
Name: moby
ID: YQNT:64YW:ANCU:MVVQ:A2KC:F7KL:RLXH:MN73:2HV4:BPS2:XMPB:23CG
Docker Root Dir: /var/lib/docker
Debug Mode (client): false
Debug Mode (server): true
 File Descriptors: 15
 Goroutines: 25
 System Time: 2017-09-26T21:53:56.9641908Z
 EventsListeners: 0
Http Proxy: http://docker.for.win.10.0.75.1:3128
Https Proxy: http://docker.for.win.10.0.75.1:3128
No Proxy: 169.254/16, 10/8,127.0.0.1,localhost
Registry: https://index.docker.io/v1/
Experimental: true
Insecure Registries:
 127.0.0.0/8
Live Restore Enabled: false

Here is docker version:

Client:
 Version:      17.06.2-ce
 API version:  1.30
 Go version:   go1.8.3
 Git commit:   cec0b72
 Built:        Tue Sep  5 19:57:19 2017
 OS/Arch:      windows/amd64

Server:
 Version:      17.06.2-ce
 API version:  1.30 (minimum version 1.12)
 Go version:   go1.8.3
 Git commit:   cec0b72
 Built:        Tue Sep  5 19:59:19 2017
 OS/Arch:      linux/amd64
 Experimental: true

• host distribution and version (Windows version, build number, etc)
  Windows 10 Enterprise Version 1607 OS Build 14393.1480
Docker for Windows 17.06.2-ce

Steps to reproduce the behavior

1. install and properly configure cntlm
2. install Docker 4 Windows
3. configure Docker proxy settings to http://docker.for.win.localhost:3128
4. do docker info observe the proxy settings
5. do docker login

[djs55]

Thanks for your report. On latest stable I see a similar problem -- when I run

docker run -it alpine sh

and then list the environment variables with set I see

http_proxy='http://docker.for.win.10.0.75.1:3128'
...

which is clearly wrong. I tried a few other combinations and it seems that something in the UI is replacing the string localhost with 10.0.75.1 (e.g. docker.uses.localhost.for.things:3128 becomes docker.uses.10.0.75.1.for.things:3128

[djs55]

As a workaround, you could set your proxy setting to http://localhost:3128 which will be rewritten to http://10.0.75.1:3128. The IP 10.0.75.1 is a private address used by a local Hyper-V network adapter-- it should be safe to configure CNTLM to bind to that.

[gorootde]

My CNTLM is bound to 10.0.75.1 and UI proxy config is set to http://localhost:3128 but nevertheless a docker search command results in proxyconnect tcp: dial tcp 10.0.75.1:3128: i/o timeout. Is there any additional thing to do?

BTW: Releasenotes of 17.09.1-ce-win42 say this issue is fixed, I am running 17.06.2-ce and it is not.

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