Tasks

Tasks describe a process or collection of actions that should be performed while Razor provisions machines. Tasks can be used to designate an operating system or other software that should be installed, where to get it, and the configuration details for the installation.

Tasks are structurally simple. They consist of a YAML metadata file and any number of ERB templates. You include the tasks you want to run in your policies (policies are described in the next section). The templates are used to generate things like the iPXE script that will boot a node into the installer, and automated installation files like kickstart, preseed or unattended files.

Razor provides a handful of existing tasks, or you can create your own. The existing tasks are primarily for installing supported operating systems.

Tasks are stored in the file system. The task_path class parameter of the pe_razor module determines where Razor looks for tasks. The parameter can include a colon-separated list of paths. Relative paths in that list are taken to be relative to the top-level Razor directory. For example, setting task_path to /opt/puppet/share/razor-server/tasks:/home/me/task:tasks makes Razor search these three directories in that order for tasks.

Storage directories

There are two directories that store tasks:

• /opt/puppetlabs/server/apps/razor-server/share/razor-server/tasks stores default tasks shipped with the product.
• /etc/puppetlabs/razor-server/tasks stores custom tasks.

Tip: We recommend not modifying the directory or tasks at /opt..., but you can copy tasks from there to the custom task directory and modify them as needed.

Task metadata

Tasks can include the following metadata in the task’s YAML file. This file is called metadata.yaml and exists in tasks/<NAME>.task where NAME is the task name. Therefore, the task name looks like this: tasks/<NAME>.task/metadata.yaml.

---
description: HUMAN READABLE DESCRIPTION
os: OS NAME
os_version: OS_VERSION_NUMBER
base: TASK_NAME
boot_sequence:
  1: boot_templ1
  2: boot_templ2
  default: boot_local

Only os_version and boot_sequence are required. The base key allows you to derive one task from another by reusing some of the base metadata and templates. If the derived task has metadata that’s different from the metadata in base, the derived metadata overrides the base task’s metadata.

The boot_sequence hash indicates which templates to use when a node using this task boots. In the example above, a node will first boot using boot_templ1, then using boot_templ2. For every subsequent boot, the node will use boot_local.

Writing task templates

Task templates are ERB templates and are searched in all the directories in the task_path configuration setting. Templates are searched in the subdirectories in this order:

1. name.task
2. base.task # If the task has a base task.
3. common

Template helpers

Templates can use the following helpers to generate URLs that point back to the server; all of the URLs respond to a GET request, even the ones that make changes on the server:

• task: Includes attributes such as name, os, os_version, boot_seq, label, description, base, and architecture.
• node: Includes attributes such as name, metadata, and facts.
• repo: Includes attributes such as name, iso_url, url.
• file_url(TEMPLATE): The URL that will retrieve TEMPLATE.erb (after evaluation) from the current node’s task.
• repo_url(PATH): The URL to the file at PATH in the current repo.
• log_url(MESSAGE, SEVERITY): The URL that will log MESSAGE in the current node’s log.
• node_url: The URL for the current node.
• store_url(VARS): The URL that will store the values in the hash VARS in the node. Currently only changing the node’s IP address is supported. Use store_url("ip" => "192.168.0.1") for that.
• stage_done_url: The URL that tells the server that this stage of the boot sequence is finished, and that the next boot sequence should begin upon reboot.
• broker_install_url: A URL from which the install script for the node’s broker can be retrieved. You can see an example in the script, os_complete.erb, which is used by most tasks.

Each boot (except for the default boot) must culminate in something akin to curl <%= stage_done_url %> before the node reboots. Omitting this will cause the node to reboot with the same boot template over and over again.

The task must indicate to the Razor server that it has successfully completed by doing a GET request against stage_done_url("finished"), for example using curl or wget. This will mark the node installed in the Razor database.

You use these helpers by causing your script to perform an HTTP GET against the generated URL. This might mean that you pass an argument like ks=<%= file_url("kickstart")%> when booting a kernel, or that you put curl <%= log_url("Things work great") %> in a shell script.

Related links:

• Task client commands
• Task APIs

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