Configuration Tasks¶

Configuration tasks are scripts called by snf-image-helper, to accomplish various configuration steps on the newly created instance. See below for a description of each one of them:

FixPartitionTable: Enlarges the last partition in the partition table of the instance, to consume all the available space and optionally adds a swap partition in the end.

FilesystemResizeUnmounted: Extends the file system of the last partition to cover up the whole partition. This only works for ext{2,3,4} file systems. Any other file system type is ignored and a warning is triggered. The task will fail if SNF_IMAGE_DEV environmental variable is missing.

MountImage: Mounts the nth partition of SNF_IMAGE_DEV, which is specified by SNF_IMAGE_PROPERTY_ROOT_PARTITION variable under the directory specified by SNF_IMAGE_TARGET. The script will fail if any of those 3 variables has a non-sane value.

AddSwap: Formats the swap partion added by FixPartitionTable task and adds an appropriate swap entry in the system's /etc/fstab. The script will only run if SNF_IMAGE_PROPERTY_SWAP is present. It will fail if SNF_IMAGE_TARGET in not defined.

DeleteSSHKeys: For linux images, this script will clear out any ssh keys found in the image and for debian, it will recreate them too. In order to find the ssh keys, the script looks in default locations (/etc/ssh/ssh_*_key) and also parses /etc/ssh/sshd_config file if present. The script will fail if SNF_IMAGE_TARGET is not set.

DisableRemoteDesktopConnections: This script temporary disables RDP connections in windows instances by changing the value fDenyTSConnection registry key. RDP connections will be enabled back during the specialize pass of the Windows setup. The task will fail if SNF_IMAGE_TARGET is not defined.

InstallUnattend: Installs the Unattend.xml files in windows images. This is needed by windows in order to perform an unattended setup. The SNF_IMAGE_TARGET variables needs to be present for this task to run.

SELinuxAutorelabel: Creates .autorelabel file in RedHat images. This is needed if SELinux is enabled to enforce an automatic file system relabeling at the next boot. The only enviromental variable required by this task is SNF_IMAGE_TARGET.

AssignHostname: Assigns or changes the hostname in a Linux or Windows image. The task will fail if the Linux distribution is not supported. For now, we support debian, redhat, slackware, suse and gentoo derived distros. The hostname is read from SNF_IMAGE_HOSTNAME variable. In addition to the latter, SNF_IMAGE_TARGET is also required.

ChangePassword: Changes the password for a list of users. For Linux systems this is accomplished by directly altering the image's /etc/shadow file. For Windows systems a script is injected into the VM's hard disk. This script will be executed during the specialize pass of the Windows setup. The list of users whose passwords will changed is determined by the SNF_IMAGE_PROPERTY_USERS variable (see here). For this task to run SNF_IMAGE_TARGET and SNF_IMAGE_PASSWORD variables need to be present.

FilesystemResizeMounted: Injects a script into a Windows image file system that will enlarge the last file system to cover up the whole partition. The script will run during the specialize pass of the Windows setup. If the SNF_IMAGE_TARGET variable is missing, the task will fail.

EnforcePersonality: Injects the files specified by the SNF_IMAGE_PROPERTY_OSFAMILY variable into the file system. If the variable is missing a warning is produced. The only environmental variable required is SNF_IMAGE_TARGET.

UmountImage: Umounts the file system previously mounted by MountImage. The only environmental variable required is SNF_IMAGE_TARGET.

Name	Pr.	Dependencies		Enviromental Variables 1
		Run-After	Run-Before	Required	Optional
FixPartitionTable	10		FilesystemResizeUnmounted	DEV
FilesystemResizeUnmounted	20	FixPartitionTable	MountImage	DEV
MountImage	30		UmountImage	DEV TARGET PROPERTY_ROOT_PARTITION
AddSwap	40	MountImage	EnforcePersonality	TARGET	PROPERTY_OSFAMILY PROPERTY_SWAP
DeleteSSHKeys	40	MountImage	EnforcePersonality	TARGET	PROPERTY_OSFAMILY
DisableRemoteDesktopConnections	40	EnforcePersonality	UmountImage	TARGET	PROPERTY_OSFAMILY
InstallUnattend	40	MountImage	EnforcePersonality	TARGET	PROPERTY_OSFAMILY
SELinuxAutorelabel	40	MountImage	EnforcePersonality	TARGET	PROPERTY_OSFAMILY
AssignHostname	50	InstallUnattend	EnforcePersonality	TARGET HOSTNAME	PROPERTY_OSFAMILY
ChangePassword	50	InstallUnattend	EnforcePersonality	TARGET PASSWORD	PROPERTY_USERS PROPERTY_OSFAMILY
FilesystemResizeMounted	50	InstallUnattend	EnforcePersonality	TARGET	PROPERTY_OSFAMILY
EnforcePersonality	60	MountImage	UmountImage	TARGET	PERSONALITY PROPERTY_OSFAMILY
UmountImage	80	MountImage		TARGET

^{1: all environmental variables are prefixed with SNF_IMAGE_}