CREATING A WINDOWS IMAGE FOR OPENSTACK(转)
2016-02-29 00:00
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CREATING A WINDOWS IMAGE FOR OPENSTACK
If you want to build a Windows image for use in your OpenStack environment, you can follow the example in the official documentation, or you can grab a Windows 2012r2 evaluation pre-built imagefrom the nice folks at CloudBase.The CloudBase-provided image is built using a set of scripts and configuration files that CloudBase has made available on GitHub.
The CloudBase repository is an excellent source of information, but I wanted to understand the process myself. This post describes the process I went through to establish an automated process for generating a Windows image suitable for use with OpenStack.
Unattended windows installs
The Windows installer supports fully automated installations through the use of an answer file, or "unattend" file, that provides information to the installer that would otherwise be provided manually. The installer will look in a number of places to find this file. For our purposes, the important fact is that the installer will look for a file namedautounattend.xmlin the root of all available read/write or read-only media. We'll take advantage of this by creating a file
config/autounattend.xml, and then generating an ISO image like this:
mkisofs -J -r -o config.iso config
And we'll attach this ISO to a vm later on in order to provide the answer file to the installer.
So, what goes into this answer file?
The answer file is an XML document enclosed in an
<unattend>..</unattend>element. In order to provide all the expected XML namespaces that may be used in the document, you would typically start with something like this:
<?xml version="1.0" ?> <unattend xmlns="urn:schemas-microsoft-com:unattend" xmlns:ms="urn:schemas-microsoft-com:asm.v3" xmlns:wcm="http://schemas.microsoft.com/WMIConfig/2002/State"> <!-- your content goes here --> </unattend>
Inside this
<unattend>element you will put one or more
<settings>elements, corresponding to the different configuration passes of the installer:
<settings pass="specialize"> </settings>
The available configuration passes are:
auditSystem
auditUser
generalize
offlineServicing
oobeSystem
specialize
windowsPE
Of these, the most interesting for our use will be:
windowsPE-- used to install device drivers for use within the installer environment. We will use this to install the VirtIO drivers necessary to make VirtIO devices visible to the Windows installer.
specialize-- In this pass, the installer applies machine-specific configuration. This is typically used to configure networking, locale settings, and most other things.
oobeSystem-- In this pass, the installer configures things that happen at first boot. We use this to step to install some additional software and run sysprep in order to prepare the image for use in OpenStack.
Inside each
<settings>element we will place one or more
<component>elements that will apply specific pieces of configuration. For example, the following
<component>configures language and keyboard settings in the installer:
<settings pass="windowsPE"> <component name="Microsoft-Windows-International-Core-WinPE" processorArchitecture="amd64" publicKeyToken="31bf3856ad364e35" language="neutral" versionScope="nonSxS"> <SetupUILanguage> <UILanguage>en-US</UILanguage> </SetupUILanguage> <InputLocale>en-US</InputLocale> <UILanguage>en-US</UILanguage> <SystemLocale>en-US</SystemLocale> <UserLocale>en-US</UserLocale> </component> </settings>
Technet provides documentation on the available components.
Cloud-init for Windows
Cloud-init is a tool that will configure a virtual instance when it first boots, using metadata provided by the cloud service provider. For example, when booting a Linux instance under OpenStack,cloud-initwill contact the OpenStack metadata service at http://169.254.169.254/ in order to retrieve things like the system hostname, SSH keys, and so forth.
While
cloud-inithas support for Linux and BSD, it does not support Windows. The folks atCloudbase have produced cloudbase-init in order to fill this gap. Once installed, the
cloudbase-inittool will, upon first booting a system:
Configure the network using information provided in the cloud metadata
Set the system hostname
Create an initial user account (by default "Admin") with a randomly generated password (see below for details)
Install your public key, if provided
Execute a script provided via cloud
user-data
Passwords and ssh keys
Whilecloudbase-initwill install your SSH public key (by default into
/Users/admin/.ssh/authorized_keys), Windows does not ship with an SSH server and cloudbase-init does not install one. So what is it doing with the public key?
While you could arrange to install an ssh server that would make use of the key,
cloudbase-inituses it for a completely unrelated purpose: encrypting the randomly generated password. This encrypted password is then passed back to OpenStack, where you can retrieve it using the
nova get-passwordcommand, and decrypt it using the corresponding SSH private key.
Running
nova get-password myinstancewill return something like:
w+In/P6+FeE8nv45oCjc5/Bohq4adqzoycwb9hOy9dlmuYbz0hiV923WW0fL 7hvQcZnWqGY7xLNnbJAeRFiSwv/MWvF3Sq8T0/IWhi6wBhAiVOxM95yjwIit /L1Fm0TBARjoBuo+xq44YHpep1qzh4frsOo7TxvMHCOtibKTaLyCsioHjRaQ dHk+uVFM1E0VIXyiqCdj421JoJzg32DqqeQTJJMqT9JiOL3FT26Y4XkVyJvI vtUCQteIbd4jFtv3wEErJZKHgxHTLEYK+h67nTA4rXpvYVyKw9F8Qwj7JBTj UJqp1syEqTR5/DUHYS+NoSdONUa+K7hhtSSs0bS1ghQuAdx2ifIA7XQ5eMRS sXC4JH3d+wwtq4OmYYSOQkjmpKD8s5d4TgtG2dK8/l9B/1HTXa6qqcOw9va7 oUGGws3XuFEVq9DYmQ5NF54N7FU7NVl9UuRW3WTf4Q3q8VwJ4tDrmFSct6oG 2liJ8s7ybbW5PQU/lJe0gGBGGFzo8c+Rur17nsZ01+309JPEUKqUQT/uEg55 ziOo8uAwPvInvPkbxjH5doH79t47Erb3cK44kuqZy7J0RdDPtPr2Jel4NaSt oCs+P26QF2NVOugsY9O/ugYfZWoEMUZuiwNWCWBqrIohB8JHcItIBQKBdCeY 7ORjotJU+4qAhADgfbkTqwo=
Providing your secret key as an additional parameter will decrypt the password:
$ nova get-password myinstance ~/.ssh/id_rsa fjgJmUB7fXF6wo
With an appropriately configured image, you could connect using an RDP client and log in as the "Admin" user using that password.
Passwords without ssh keys
If you do not provide your instance with an SSH key you will not be able to retrieve the randomly generated password. However, if you can get console access to your instance (e.g., via the Horizon dashboard), you can log in as the "Administrator" user, at which point you will be prompted to set an initial password for that account.Logging
You can find logs forcloudbase-initin
c:\program files (x86)\cloudbase solutions\cloudbase-init\log\cloudbase-init.log.
If appropriately configured,
cloudbase-initwill also log to the virtual serial port. This log is available in OpenStack by running
nova console-log <instance>. For example:
$ nova console-log my-windows-server 2014-11-19 04:10:45.887 1272 INFO cloudbaseinit.init [-] Metadata service loaded: 'HttpService' 2014-11-19 04:10:46.339 1272 INFO cloudbaseinit.init [-] Executing plugin 'MTUPlugin' 2014-11-19 04:10:46.371 1272 INFO cloudbaseinit.init [-] Executing plugin 'NTPClientPlugin' 2014-11-19 04:10:46.387 1272 INFO cloudbaseinit.init [-] Executing plugin 'SetHostNamePlugin' . . .
Putting it all together
I have an install script that drives the process, but it's ultimately just a wrapper forvirt-installand results in the following invocation:
exec virt-install -n ws2012 -r 2048 \ -w network=default,model=virtio \ --disk path=$TARGET_IMAGE,bus=virtio \ --cdrom $WINDOWS_IMAGE \ --disk path=$VIRTIO_IMAGE,device=cdrom \ --disk path=$CONFIG_IMAGE,device=cdrom \ --os-type windows \ --os-variant win2k8 \ --vnc \ --console pty
Where
TARGET_IMAGEis the name of a pre-existing
qcow2image onto which we will install Windows,
WINDOWS_IMAGEis the path to an ISO containing Windows Server 2012r2,
VIRTIO_IMAGEis the path to an ISO containing VirtIO drivers for Windows (available from the Fedora project), and
CONFIG_IMAGEis a path to the ISO containing our
autounattend.xmlfile.
The fully commented autounattend.xml file, along with the script mentioned above, are available in my windows-openstack-image repository on GitHub.
The answer file in detail
windowsPE
In the windowsPE phase, we start by configuring the installer locale settings:<component name="Microsoft-Windows-International-Core-WinPE" processorArchitecture="amd64" publicKeyToken="31bf3856ad364e35" language="neutral" versionScope="nonSxS"> <SetupUILanguage> <UILanguage>en-US</UILanguage> </SetupUILanguage> <InputLocale>en-US</InputLocale> <UILanguage>en-US</UILanguage> <SystemLocale>en-US</SystemLocale> <UserLocale>en-US</UserLocale> </component>
And installing the VirtIO drviers using the Microsoft-Windows-PnpCustomizationsWinPE component:
<component name="Microsoft-Windows-PnpCustomizationsWinPE" publicKeyToken="31bf3856ad364e35" language="neutral" versionScope="nonSxS" processorArchitecture="amd64"> <DriverPaths> <PathAndCredentials wcm:action="add" wcm:keyValue="1"> <Path>d:\win8\amd64</Path> </PathAndCredentials> </DriverPaths> </component>
This assumes that the VirtIO image is mounted as drive
d:.
With the drivers installed, we can then call the Microsoft-Windows-Setup component to configure the disks and install Windows. We start by configuring the product key:
<component name="Microsoft-Windows-Setup" publicKeyToken="31bf3856ad364e35" language="neutral" versionScope="nonSxS" processorArchitecture="amd64"> <UserData> <AcceptEula>true</AcceptEula> <ProductKey> <WillShowUI>OnError</WillShowUI> <Key>INSERT-PRODUCT-KEY-HERE</Key> </ProductKey> </UserData>
And then configure the disk with a single partition (that will grow to fill all the available space) which we then format with NTFS:
<DiskConfiguration> <WillShowUI>OnError</WillShowUI> <Disk wcm:action="add"> <DiskID>0</DiskID> <WillWipeDisk>true</WillWipeDisk> <CreatePartitions> <CreatePartition wcm:action="add"> <Order>1</Order> <Extend>true</Extend> <Type>Primary</Type> </CreatePartition> </CreatePartitions> <ModifyPartitions> <ModifyPartition wcm:action="add"> <Format>NTFS</Format> <Order>1</Order> <PartitionID>1</PartitionID> <Label>System</Label> </ModifyPartition> </ModifyPartitions> </Disk> </DiskConfiguration>
We provide information about what to install:
<ImageInstall> <OSImage> <WillShowUI>Never</WillShowUI> <InstallFrom> <MetaData> <Key>/IMAGE/Name</Key> <Value>Windows Server 2012 R2 SERVERSTANDARDCORE</Value> </MetaData> </InstallFrom>
And where we would like it installed:
<InstallTo> <DiskID>0</DiskID> <PartitionID>1</PartitionID> </InstallTo> </OSImage> </ImageInstall>
specialize
In the specialize phase, we start by setting the system name to a randomly generated value using the Microsoft-Windows-Shell-Setup component:<component name="Microsoft-Windows-Shell-Setup" publicKeyToken="31bf3856ad364e35" language="neutral" versionScope="nonSxS" processorArchitecture="amd64"> <ComputerName>*</ComputerName> </component>
We enable remote desktop because in an OpenStack environment this will probably be the preferred mechanism with which to connect to the host (but see this document for an alternative mechanism).
First, we need to permit terminal server connections:
<component name="Microsoft-Windows-TerminalServices-LocalSessionManager" processorArchitecture="amd64" publicKeyToken="31bf3856ad364e35" language="neutral" versionScope="nonSxS"> <fDenyTSConnections>false</fDenyTSConnections> </component>
And we do not want to require network-level authentication prior to connecting:
<component name="Microsoft-Windows-TerminalServices-RDP-WinStationExtensions" processorArchitecture="amd64" publicKeyToken="31bf3856ad364e35" language="neutral" versionScope="nonSxS"> <UserAuthentication>0</UserAuthentication> </component>
We will also need to open the necessary firewall group:
<component name="Networking-MPSSVC-Svc" processorArchitecture="amd64" publicKeyToken="31bf3856ad364e35" language="neutral" versionScope="nonSxS"> <FirewallGroups> <FirewallGroup wcm:action="add" wcm:keyValue="RemoteDesktop"> <Active>true</Active> <Profile>all</Profile> <Group>@FirewallAPI.dll,-28752</Group> </FirewallGroup> </FirewallGroups> </component>
Finally, we use the Microsoft-Windows-Deployment component to configure the Windows firewall to permit ICMP traffic:
<component name="Microsoft-Windows-Deployment" processorArchitecture="amd64" publicKeyToken="31bf3856ad364e35" language="neutral" versionScope="nonSxS"> <RunSynchronous> <RunSynchronousCommand wcm:action="add"> <Order>3</Order> <Path>netsh advfirewall firewall add rule name=ICMP protocol=icmpv4 dir=in action=allow</Path> </RunSynchronousCommand>
And to download the
cloudbase-initinstaller and make it available for later steps:
<RunSynchronousCommand wcm:action="add"> <Order>5</Order> <Path>powershell -NoLogo -Command "(new-object System.Net.WebClient).DownloadFile('https://www.cloudbase.it/downloads/CloudbaseInitSetup_Beta_x64.msi', 'c:\Windows\Temp\cloudbase.msi')"</Path> </RunSynchronousCommand> </RunSynchronous> </component>
We're using Powershell here because it has convenient methods available for downloading URLs to local files. This is roughly equivalent to using
curlon a Linux system.
oobeSystem
In the oobeSystem phase, we configure an automatic login for the Administrator user:<UserAccounts> <AdministratorPassword> <Value>Passw0rd</Value> <PlainText>true</PlainText> </AdministratorPassword> </UserAccounts> <AutoLogon> <Password> <Value>Passw0rd</Value> <PlainText>true</PlainText> </Password> <Enabled>true</Enabled> <LogonCount>50</LogonCount> <Username>Administrator</Username> </AutoLogon>
This automatic login only happens once, because we configure
FirstLogonCommandsthat will first install
cloudbase-init:
<FirstLogonCommands> <SynchronousCommand wcm:action="add"> <CommandLine>msiexec /i c:\windows\temp\cloudbase.msi /qb /l*v c:\windows\temp\cloudbase.log LOGGINGSERIALPORTNAME=COM1</CommandLine> <Order>1</Order> </SynchronousCommand>
And will then run
sysprepto generalize the system (which will, among other things, lose the administrator password):
<SynchronousCommand wcm:action="add"> <CommandLine>c:\windows\system32\sysprep\sysprep /generalize /oobe /shutdown</CommandLine> <Order>2</Order> </SynchronousCommand> </FirstLogonCommands>
The system will shut down when
sysprepis complete, leaving you with a Windows image suitable for uploading into OpenStack:
glance image-create --name ws2012 \ --disk-format qcow2 \ --container-format bare \ --file ws2012.qcow2
Troubleshooting
If you run into problems with an unattended Windows installation:During the first stage of the installer, you can look in the
x:\windows\pantherdirectory for
setupact.logand
setuperr.log, which will have information about the early install process. The
x:drive is temporary, and files here will be discarded when the system reboots.
Subsequent installer stages will log to
c:\windows\panther\.
If you are unfamiliar with Windows, the
typecommand can be used very much like the
catcommand on Linux, and the
morecommand provides paging as you would expect. The
notepadcommand will open a GUI text editor/viewer.
You can emulate the
tailcommand using
powershell; to see the last 10 lines of a file:
C:\> powershell -command "Get-Content setupact.log -Tail 10"
Technet has a Deployment Troubleshooting and Log Files document that discusses in more detail what is logged and where to find it.
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