MAC Address changes after container restart even with ip specified.

[Umer-Javaid]

In reference to github/docker/for-win/#2399
I have created a microsoft/dotnet-framework:4.7.2-runtime container using docker for windows. Each time the container restarts a new MAC address is assigned to it even though I have explicitly specified IP-Address at the creation.

Expected behavior

MAC address should not change after container restart when IP-Address is specified explicitly.

Actual behavior

MAC address changes after each restart.

PS C:\> docker create --name=testContainer --net=transNet1 --ip=10.2.0.251 microsoft/dotnet-framework:4.7.2-runtime
e041405ce6ec21cb28e87923d8ca919919f1f38b9246332fbabaf32be25ba4ab
PS C:\> docker start testContainer
testContainer
PS C:\> docker inspect --format='{{range .NetworkSettings.Networks}}{{println .MacAddress}}{{end}}' testContainer
00:15:5d:71:18:58

PS C:\> docker stop testContainer
testContainer
PS C:\> docker start testContainer
testContainer
PS C:\> docker inspect --format='{{range .NetworkSettings.Networks}}{{println .MacAddress}}{{end}}' testContainer
00:15:5d:71:1e:f4

Information

• Windows Version:

  Platform ServicePack Version      VersionString
  -------- ----------- -------      -------------
  Win32NT             10.0.14393.0 Microsoft Windows NT 10.0.14393.0

• Docker for Windows Version:

  Client:
   Version:      18.03.1-ee-2
   API version:  1.37
   Go version:   go1.10.2
   Git commit:   ebbcd7e
   Built:        Tue Jul 10 21:32:32 2018
   OS/Arch:      windows/amd64
   Experimental: false
  
  Server:
   Engine:
   Version:      18.03.1-ee-2
   API version:  1.37 (minimum version 1.24)
   Go version:   go1.10.2
   Git commit:   ebbcd7e
   Built:        Tue Jul 10 21:49:06 2018
   OS/Arch:      windows/amd64
   Experimental: false

Steps to reproduce the behavior

1. docker pull microsoft/dotnet-framework:4.7.2-runtime
2. Create a container with explicit IP-Address specified
3. Start the container
4. Inspect the container to see MAC-Address
5. Stop the container and then start again
6. Inspect the container again to see MAC-Address