• Table of contents
• Templates
  • Accessing Templates
    • Host-based Rendering
    • Hostgroup-based rendering
    • PXE Menus
  • Writing templates
  • Functions and macros:
    • Kickstart only variables (Only available for provision templates and "RedHat" Family operating systems):
    • Preseed attributes (Only available for provision templates and "Debian" Family operating systems)::
    • Host- or Hostgroup parameters
    • Compute Resource Specific functions
    • Settings
  • Ruby methods

Templates¶

The following functions and macros can be used within templates. These are guaranteed to work via the safemode rendering, to ensure a template can do nothing harmful. With safemode disabled other macros may work, but are not supported at this time.

To enable safemode, set "safemode_render" to "true" in Settings -> Foreman settings. Safemode rendering prevents templates from reading and writing files on the file system or modifying application data within foreman.

Accessing Templates¶

There are two ways to render a template, based on a single host, or based on a Hostgroup. The host or hostgroup provides all the details with which to render the template.

Host-based Rendering¶

Only a single template of each type may be rendered for a system. Foreman determines which template to use following these rules:

1. Only the templates of the appropriate kind and associated with the hosts operating system are considered
2. If a template has a hostgroup/environment combination that matches that of the host, use this template else
3. If a template is associated with the environment of the host, use this template, else
4. Use the first template found associated with the operating system associated with the host.

So essentially, the hostgroup/environment combination is used first, then just the environment, and finally just the operating system of the host.

To access a template of a certain type simply use this url:

/unattended/KIND_NAME

For example: /unattended/provision
would render the provisioning template. The host will be based on the IP Address it is accessed from. To spoof a template simply access the url in this manner:

/unattended/provision?spoof=192.168.0.1

where 192.168.0.1 is the ip address of the system you want to spoof. This allows you to view a template for a particular system from anywhere.

Hostgroup-based rendering¶

Allows any template to be rendered for any host group. When rendering using a hostgroup, @host is actually the hostgroup instead of a defined host. The default values for the hostgroup are used for templated values. This means if a value is not set in the hostgroup, you may get an error when rendering the template. To access a template using a Hostgroup to render, simply use this URL:

/unattended/template/Template Name/Hostgroup Name

For example, a hostgroup of name Finance, and a template named WebServerKickstart could be rendered using the url:

/unattended/template/WebServerKickstart/Finance

When building the default PXE template (from the Provisioning Templates page), any host group with the operating system, installation media and architecture set, plus provisioning templates with the host group set on the Associations tab will be listed at the bottom of the menu.

PXE Menus¶

Pxe Menus can be deployed to smart proxies from the Config Templates list page (/config_templates). All provision templates will be added with each of their hostgroup combinations(see above). For example if the template "WebServerKickstart" is associated to the Hostgroup1/Production, Hostgroup2/Production, and Hostgroup2/Testing combinations, the template would only be added twice. Once for WebServerKickstart-Hostgroup1 and WebServerKickstart-Hostgroup2.

Writing templates¶

Templates can be written using common ERB style templating. Here's an example on using a variable/function:

@rootpw --iscrypted <%= root_pass %>@

Using a simple conditional:

@<%= "selinux --disabled\n" if @osver != 3 -%>@

This would include a line to disable selinux if the operating system version is not 3 (since Selinux isn't supported on RHEL 3)

Another way to do conditional (with if/elsif/else):

<% if @osver == 5 -%>
 echo "uses yum" 
<% elsif @osver == 4 -%>
 echo "uses up2date
<% else -%>
 echo "I'm not sure" 
<% end -%>

Functions and macros:¶

Name	Description	Example
root_pass	The root password configured for the system
ks_console	A string assembled using the port and baud of the host which can be added to a kernel line	ks_console => console=ttyS1,9600
snippet(name)	Renders the specified snippet
foreman_url(kind)	Provides the full URL to a host-rendered template of the given kind	foreman_url("provision") => http://HOST/unattended/provision
@host.name	The (full) name of the host
@host.shortname	The (short) name of the host
@host.certname	The SSL certificate name of the host
@host.domain	The domain of the host
@host.ip	The IP address of the host
@host.hostgroup	The hostgroup of the host	<% if @host.hostgroup.to_s == "Base/Application Servers" -%>...<% end -%>
@host.mac	The HW address of the host
@host.diskLayout	The disklayout of the host (could come from the operating system)
@host.ptable	The disklayout name	<% if @host.ptable.name == 'Kickstart RHEL default' %> .. <% end %>
@host.puppetmaster	The puppetmaster the host should use
@host.environment	The environment the host should use
@host.location	The location of the host
@host.architecture	The arch of the host (i.e. x86_64)
@host.operatingsystem.name	The operating system name
@host.operatingsystem.major	The major version of the OS	<% if @host.operatingsystem.major.to_i < 7 %> .. <% end %>
@host.operatingsystem.minor	The minor version of the OS	<% if @host.operatingsystem.minor.to_i > 2 %> .. <% end %>
@host.operatingsystem.family	The OS Family (I.e. Redhat, Debian, etc.)
@host.os.medium_uri(@host)	The url for provisioning (path configured in installation media)	<%= @host.os.medium_uri(@host) %> => http://mirror.os.org/os/
@host.subnet.mask	The subnet mask of the host
@host.subnet.gateway	The gateway of the host
@host.subnet.dns_primary	The primary DNS of the host
@host.subnet.dns_secondary	The secondary DNS of the host
@host.subnet.dhcp	Boolean that render true if a dhcp proxy is configured for this host	<% if @host.subnet.dhcp %> .. <% else %> .. <% end %>
@host.url_for_boot(:kernel)	Full url to the kernel associated with this host.
@host.url_for_boot(:initrd)	Full url to the initrd image associated with this host
@host.sp_name	The name of the BMC interface
@host.sp_ip	The IP address of the BMC interface
@host.sp_mac	The HW address of the BMC interface
@host.sp_subnet	Subnet of the BMC network
@host.interfaces	Contains an array of all available host interfaces including primary (see networking notes below for changes between Foreman versions)
@host.primary_interface	Returns host's primary interface (1.8+)	it existed in 1.7, returning primary_interface identifier based on imported facts, 1.8+ it returns interface object
@host.provision_interface	Returns host's provision interface (1.8+)	returns interface object, see notes below for more details
@host.bond_interfaces	Contains an array of all bonds (1.7+)
@host.managed_interfaces	Limit the array to managed (non-BMC nor Bond) interfaces only which are set to be managed (1.7+)
@host.interfaces_with_identifier(['eth0', 'eth1'])	Returns array of interfaces with given identifier (1.7+)
@host.interfaces.managed	Limit the array to managed (non-BMC nor Bond) interfaces only (only works if safemode_render=false)
@host.interfaces.bmc	Limit the array to BMC (non-managed) interfaces only (only works if safemode_render=false)
@host.interfaces.size	Number of additional interfaces (either type interface or bmc) (only works if safemode_render=false)	size=1 means a host has two interfaces on 1.7, one interface on 1.8+
@host.interfaces.empty	If true host does not have ant interface (only works if safemode_render=false)
@host.facts	Contains a hash of facts from Facter/Ohai etc. (1.7.2+)
@host.facts['ipaddress']	Accessing the 'ipaddress' fact for the host (1.7.2+)
@host.facts_hash	Contains a hash of facts from Facter/Ohai etc. (only works if safemode_render=false)
@host.facts_hash['ipaddress']	Accessing the 'ipaddress' fact for the host (only works if safemode_render=false)
@host.image_build?	Returns true if the host is provisioned using an image (1.5+)	<% if @host.image_build? %>
@host.pxe_build?	Returns true if the host is provisioned using the network/PXE (1.5+)	<% if @host.pxe_build? %>
@provisioning_type	Equal to 'host' or 'hostgroup' depending on type of provisioning (1.6+)	<% if @provisioning_type == 'hostgroup' %>
@static	Boolean value to determine if the network configuration is static or dynamic	Use <%= @static ? "static" : "dynamic" %> in templates
@template_name	Name of the template being rendered (1.7+)	<%= @template_name %>

NOTE: For PXELinux templates in 0.4 or older only leave off the '@host.' from the above as it is currently generated slightly different from everything else.

NOTE: The interface array can be parsed this way:

<% @host.interfaces.each do |i| %> key is <%= i.ip %> <% end %>

. To print information for the first interface in the array, try something like:

<% myinterface = @host.interfaces.first %> IP: <%= myinterface.ip %> Netmask: <%= myinterface.subnet.mask %> Gateway: <%= myinterface.subnet.gateway %>

NOTE: Some variables can't be accessed while safemode is enabled. Disable via safemode_render in More > Settings, though be aware this enables arbitrary code to be added to templates. Some are being whitelisted via #2948.

NOTE: You may need to add "&static=yes" to the foreman_url to use the @static parameter in templates (see KickstartStatic).

NOTE: A lot of networking functions changed their meaning between 1.7 and 1.8 releases. In 1.7, primary interface used to be part of host object so it was not part of '@host.interfaces'. Also it could be detected by '@host.has_primary_interface?' which was removed in 1.8. For more advanced example of using networking functions, see kickstart_networking_setup.erb provisioning template snippet.

NOTE: If you get interface object as a returning value of some function (e.g. primary_interface or interfaces.first) it is evaluated to its DNS name by default. You can easily get to other attributes of such interface, e.g. @host.primary_interface.identifier or @host.primary_interface.mac. Valid attributes include: "managed?", "subnet" (returns subnet object), "virtual?", "physical?", "mac", "ip", "identifier", "attached_to", "link", "tag", "domain" (returns domain object), "vlanid", "bond_options", "attached_devices", "mode", "attached_devices_identifiers", "primary", "provision", "alias?", "inheriting_mac" (if it's virtual it inherits the mac from attached_to device)

Kickstart only variables (Only available for provision templates and "RedHat" Family operating systems):¶

Name	Description	Example
@osver	The OS Major Version (Same as @host.operatingsystem.major)
@arch	The architecture (same as @host.architecture.name)
@mediapath	The full kickstart line to provide the url command.	@mediapath => http://file.example.com/RHEL-5-Server/U5/x86_64/os/
@epel	A command which will automatically install the correct version of the epel-release rpm. Use full in a %post script.	@epel => "su -c 'rpm -Uvh http://download.fedora.redhat.com/pub/epel/5/x86_64/epel-release-5-4.noarch.rpm'"
@dynamic	true if the parition table being used is a %pre script (has #Dynamic as the first line of the table)	<% if @dynamic -%>

Preseed attributes (Only available for provision templates and "Debian" Family operating systems)::¶

Name	Description	Example
@preseed_path
@preseed_server

Host- or Hostgroup parameters¶

@host.params['parameter_name']

If you need to test if a parameter contains a boolean true/false value, there are two helpers that will help:

@host.param_true?('parameter_name')
@host.param_false?('parameter_name')

These check the parameter is a true/false/on/off/1/0 string.

Hint: For Foreman older than 1.0 you have to disable Safemode-Rendering in More->Settings.

Compute Resource Specific functions¶

see Compute Resources

Settings¶

Setting.setting_name

You will need to disable Safemode-Rendering in More->Settings.

Ruby methods¶

The most common methods on Ruby's core classes should be allowed (split, gsub, to_i, blank?, etc). A full list is in the Safemode Gem: https://github.com/svenfuchs/safemode/blob/master/lib/safemode/core_jails.rb#L33

To avoid turning off safemode, consider alternative ways of writing your ruby code. For example this would not work in the default Jail:

@host.ip.rpartition('.')[-1]

But this does:

@host.ip.split('.').last