Template

The template object defines a templated content that can be referenced by its ID. The content of the template (or in-line template in a bootenv object) is a golang text/template string. The template has a set of special expansions. The normal expansion syntax is:

{{ .Machine.Name }}

This would expand to the machine's Name field. There are helpers for the parameter spaces, the bootenv object, and some miscellaneous functions. Additionally, the normal golang text/template functions are available as well. Things like range, len, and comparators are available as well. Template inclusion is supported by the following syntax:

{{ template "ID of Template" . }}
{{ template .Param.MyFavoriteTemplate . }}

The following table lists the current set of expansion custom functions.

Expansion	Description
.ApiHostURL	HTTPS URL to access the DRP API uisng the server hostname.
.ApiURL	HTTPS URL to access the DRP API.
.BootParams	Renders the bootparam field of the bootenv. Template expansion applies to that field as well.
.ComposeParam <key>	Returns the composed value of a parameter across all param sources instead of just the highest precedence.
.CurrentJob	Returns the UUID of the job running the template expansion (if rendering in a job context). This handles differentiating figuring out if the task is a work order or not.
.Env.InstallUrl	HTTP URL to the base ISO install directory.
.Env.JoinInitrds <protocol>	A comma separated string of all the initrd files specified in the bootenv reference through the specified protocall (either tftp or http).
.Env.OS.Family	An optional string from the bootenv that is used to represent the OS family. Ubuntu preseed uses this to determine Debian or Ubuntu as an example.
.Env.OS.Version	An optional string from the bootenv that is used to represent the OS version. Ubuntu preseed uses this to determine what version of ubuntu is being installed.
.Env.PathFor <protocol> <file>	This references the boot environment and builds a string that presents a either a TFTP or HTTP specifier into exploded ISO space for that file. The protocol is either tftp or http. The file is a relative path inside the ISO.
.GenerateToken	This generates a limited use access token for the machine to either update itself, or create a new machine. The token's validity is limited in time by .
.InstallRepos	Returns exactly one repo from the list chosen by MachineRepos function that has installSource set, and at most one repo from the MachineRepos function that has securitySource set.
.Machine.Address	The Address field of the machine.
.Machine.CurrentJob	Returns the UUID of the job running the template expansion (if rendering in a Job context). Note: use .CurrentJob in DRP v4.10+.
.Machine.HexAddress	The Address field of the machine in hex (useful for elilo config files).
.Machine.Name	The FQDN of the machine in the machine object stored in the Name field.
.Machine.Path	A path to a machine's unique space in the file server name space.
.Machine.ShortName	The name part of the FDQN of the machine object stored in the Name field.
.Machine.Url	A HTTP URL that references the machine's unique filesystem space.
.Machine.UUID	The machine's UUID field.
.MachineRepos	Returns all repos that have the OS of the machine defined in their os section.
.ObjectExpand <object>	Returns the expanded object from the provided object. This can iterate through arrays and maps.
.Param <key>	Returns the structure for the specified key for this rendering.
.ParamAsJSON <key>	Return the specified parameter as a JSON string or an error.
.ParamAsYAML <key>	Return the specified parameter as a YAML string or an error.
.ParamCompose <key>	Same as .ComposeParam, but matches the other param function naming conventions.
.ParamComposeExpand <key>	Returns the specified parameter after composing and then doing string expansion.
.ParamExists <key>	Returns true if the specified key is a valid parameter available for this rendering.
.ParamExpand <key>	Runs templating on the contents of a parameter before returning it. It iterates through maps and arrays to find expandable strings.
.ParseURL <segment> <url>	Parse the specified URL and return the segment requested. Supported segments follow an be one of the following schemes https, host (eg: drp.example.com:8092), or path (eg: /api/v3/machines). Note that host does not separate name and port.
.ProvisionerAddress	An IP address that is on the provisioner that is the most direct access to the machine.
.ProvisionerHostURL	An HTTP URL to access the base file server root using the server hostname.
.ProvisionerURL	An HTTP URL to access the base file server root.
.Repos <tag>, <tag>, ...	Returns repos as defined by the package-repositories param currently in scope with the matching tags.
.SecureProvisionerHostURL	An HTTPS URL to access the base file server root using the server hostname.
.SecureProvisionerURL	An HTTPS URL to access the base file server root.
.StringExpand <string>	Returns the expanded string from the provided template string.
.Task.TargetOS	Returns a string that presents the OS of the runner. This can be esxi, linux, darwin, or windows.
.WorkOrder.CurrentJob	Returns the UUID of the job running the template expansion (if rendering in a job context).
.WorkOrder.Machine	The Machine's UUID field in the work order.
.WorkOrder.UUID	The work order's UUID field.
template <string> .	Includes the template specified by the string. The string can be a variable Note: template does not have a dot (.) in front of it.

Note

.GenerateToken generates either a known or unknown token for use by the template to update objects in DRP. The tokens are valid for a limited time as defined by the knownTokenTimeout and unknownTokenTimeout preferences. The tokens are also restricted to the function they can perform. The known token is limited to only reading and updating the specific machine the template is being rendered for. If a machine is not present during the render, an unknown token is generated that has the ability to query and create machines. These are used by the install process to indicate that the install is finished and that the local bootenv should be used for the next boot and during the discovery process to create the newly discovered machine.

Note

.Machine.Path is particularly useful for ensuring that templates are expanded into a unique file space for each machine. An example of this is per machine kickstart files. These can be seen in the ubuntu-16.04-install bootenv.

With regard to the .Param and .ParamExists functions, these return the parameter or existence of the parameter specified by the key input. The parameters are examined from most specific to global. This means that the Machine object's profile is checked first, then the list of profiles associated with the machine, and finally the global profile. The parameters are stored in a profile.

The default template and bootenv use the following optional (unless noted with "*") parameters.

Parameter	Type	Description
ntp_servers	Array of string	The format is an array of IP addresses in dotted quad format.
proxy-servers	Array of objects	See the parameter definition.
operating-system-disk	String	A string to use as the default install drive. Examples include /dev/sda, or sda depending upon kickstart or preseed.
access-keys	Map of strings	The key is the name of the public key. The value is the public key. All keys are placed in the .authorized_keys file for the root account.
provisioner-default-password-hash	String	The password hash for the initial default password, RocketSkates
provisioner-default-user	String	The initial user to create for ubuntu/debian installs
dns-domain	String	DNS Domain to use for this system's install
operating-system-license-key *	String	Windows only
operating-system-install-flavor *	String	Windows only

For some examples of this in use, see as well as the example profiles in the assets directory.

Sub-templates

A template may contain other templates as described above. The system comes with some pre-existing sub-templates to make kickstart and preseed generation easier. The following templates are available had have some parameters that drive them. The required parameters can be applied through profiles or the machine profile. The templates contain comments with how to use and parameters to set.

JSON Template Fields

Field	Definition
Contents	Contents is the raw template. It must be a valid template according to text/template. required: true
Description	Description is a string for providing a simple description
EndDelimiter	EndDelimiter is an optional end delimiter. required: false
ID	ID is a unique identifier for this template. It cannot change once it is set. required: true
Meta	Meta contains the meta data of the object. The type of this field is a key / value map/dictionary. The key type is string. The value type is also string. The general content of the field is undefined and can be an arbritary store. There are some common known keys: color - The color the UX uses when displaying icon - The icon the UX uses when displaying * title - The UX uses this for additional display information. Often the source of the object. Specific Object types use additional meta data fields. These are described at: https://docs.rackn.io/stable/redirect/?ref=rs_object_metadata
StartDelimiter	StartDelimiter is an optional start delimiter. required: false