Posts Tagged ‘containers’

Linux containers vs Windows containers; another eternal war starts!

February 29, 2016 Leave a comment

Hi again!,

Yes the containers are the future. We can develop virtual machines into containers, containers into virtual machines, virtual appliances into containers, containers into virtual machines into containers, etc. You can’t limit imagination.

Containers are not a new technology. As a Microsoft specialist, I had no information about it before because it came from the Unix/Linux world through mecanisms like namespaces, cgroups and capabilities. Microsoft has decided to integrate this beautiful technology into its new OS Windows Server 2016.

You can develop some containers using the CTP4 and Docker engine.

Containers have the ability to start very fast but the question is : are Windows containers faster or slower than Linux containers?

I took two virtual machines on my Laptop with these configurations:

  1. Windows Server Core 2016 CTP 4. 4GB RAM, 2 virtual CPU. Docker version 1.10.0-dev, build e39c811, experimental
  2. Linux Ubuntu 15.04, 4GB RAM, 2 virtual CPU. Docker version 1.10.0-dev, build 59a341e

A container is created based on the underlying OS on each virtual machine. Let us see the starting and stopping times. I noticed that the Linux containers start faster after the first bootstrapping.

Windows Linux
Starting Time : 11-12s

Stopping Time : 12-13s

1st Starting Time : 2-4s, 2nd ST: 1-2s

Stopping Time : 11-12s

What about a more powerful platform like Azure? I have two virtual machines with the same configurations:

Windows Linux
Starting Time : 3-4s

Stopping Time : 2-4s

1st Starting Time : 2-3s, 2nd ST: 0-0.3s!

Stopping Time : 10-10.5s

As a quick conclusion, we can see that Linux containers are 10 times faster than Windows containers.

Microsoft has to deal with the containers performances and has a lot of work. Let us wait for the release version.

Categories: docker Tags: ,

–net=Host option not recognized under Windows 2016 CTP4

February 26, 2016 Leave a comment

Hi again,

After docker on Linux, I was playing with the new Windows containers using docker engine.

Before starting, I explain quickly my environment; I have deployed a virtual machine based on Windows Server Core CTP4 and I deployed the containers feature on it. By default the script used to provision a container host “Install-ContainerHost.ps1” creates a virtual switch named Virtual Switch using the NAT connection type; finally this feature is available! Before, we was obliged to use the routing services into an other virtual machine for example.


On Linux I was able to create my containers using the same network stack as my host. So I had just to create ports forwarding rules from my host to my container. To achieve this goal we use –net=Host option.

I created a container from the WindowsServerCore image using this command:


However this option is not accepted. How to configure my docker network?

Under Windows, a file named “runDockerDaemon.cmd” located under c:\ProgramData\docker folder defines the default VSwitch to use when creating containers.


As expected, the “Virtual Switch” switch is defined by default. If you want to use an external vswitch, you have just to define it in the runDockerDaemon file.

@echo off
set certs=%ProgramData%\docker\certs.d

if exist %ProgramData%\docker (goto :run)
mkdir %ProgramData%\docker

if exist %certs%\server-cert.pem (if exist %ProgramData%\docker\tag.txt (goto :secure))

docker daemon -D -b “Virtual Switch”
goto :eof

docker daemon -D -b “Virtual Switch” -H –tlsverify –tlscacert=%certs%\ca.pem –tlscert=%certs%\server-cert.pem –tlskey=%certs%\server-key.pem

According to Microsoft, “Each container needs to be attached to a virtual switch in order to communicate over a network. A virtual switch is created with the New-VMSwitch command. Containers support a virtual switch with type External or NAT"

I think that with VSwitches containers manage their own networks stacks. An overhead is created consequently. Under Linux, we can bypass this layer and use the host network stack directly.


Categories: docker Tags: ,