Pipeline Elements¶

Pipeline Elements (PEs) are a consistent workflow template pattern used in DRP pipelines. They are NOT a separate runner mode — PEs are workflows delivered as content packs that follow a standardized stage structure, making them composable building blocks for the provisioning pipeline.

The reference implementations are in the universal content pack: universal-discover, universal-hardware, universal-burnin, and universal-linux-install. All follow the same stage pattern:

1. Initial unique work — stages specific to this pipeline element's purpose
2. pre-callback — announces pipeline entry (e.g., universal-hardware-start-callback)
3. pre-flexiflow — injection point for pre-work customization (e.g., universal-hardware-pre-flexiflow)
4. Specific work stages — the core work (e.g., ipmi-inventory, raid-configure, bios-configure)
5. post-flexiflow — injection point for post-work customization (e.g., universal-hardware-post-flexiflow)
6. Classification — classification validation point to select next pipeline step (e.g., universal-hardware-classification)
7. Validation — post-work validation injection point (e.g., universal-hardware-post-validation)
8. post-callback — announces pipeline completion (e.g., universal-hardware-complete-callback)
9. Chain task — universal-chain-workflow selects and starts the next pipeline element

Example: universal-hardware Workflow¶

The following is the actual stage list from the universal-hardware content pack:

---
Name: universal-hardware
Description: "Hardware IPMI, Flash, RAID and BIOS"
Documentation: |
  Universal Workflow for the hardware

Meta:
  pipeline: start
  color: olive
  icon: map signs
  title: RackN Content
Stages:
  - discover
  - universal-hardware-start-callback
  - universal-hardware-pre-classification
  - universal-hardware-pre-flexiflow
  - hardware-tools-install
  - raid-tools-install
  - ipmi-inventory
  - ipmi-configure
  - flash
  - ipmi-reset-to-factory
  - ipmi-inventory
  - raid-enable-encryption
  - raid-configure
  - bios-reset-to-factory
  - bios-inventory
  - bios-configure
  - universal-hardware-post-flexiflow
  - bios-complete
  - universal-hardware-classification
  - universal-hardware-post-validation
  - universal-hardware-complete-callback
  - universal-chain-workflow
  - complete-nobootenv

Flexiflow Injection Points¶

The pre-flexiflow and post-flexiflow stages are the primary way developers add custom behavior to existing pipeline elements WITHOUT modifying the PE itself. Each flexiflow stage reads a parameter that contains the list of stages to inject. For example, universal-hardware-post-flexiflow reads universal/hardware-post-flexiflow. Set that parameter to inject stages after the hardware work:

# Inject a custom stage into the post-flexiflow of universal-hardware
drpcli profiles set global param universal/hardware-post-flexiflow \
    to '["my-custom-hardware-validate"]'

This allows site-specific customization to be delivered as a separate content pack without forking the upstream PE. The PE itself remains unmodified and upgradeable independently.

Building a Pipeline Element¶

The recommended starting point for a new Pipeline Element is to clone the universal-runbook PE from the rackn/content/universal content pack. universal-runbook is the simplest reference PE — it provides the full standard stage structure with application delivery via during-flexiflow injection — making it the right template to copy and adapt.

The universal-runbook workflow (rackn/content/universal/content/workflows/universal-runbook.yaml) provides:

Stages:
  - start
  - universal-runbook-start-callback
  - universal-runbook-pre-classification
  - universal-runbook-pre-flexiflow
  - universal-runbook-during-flexiflow
  - universal-runbook-post-flexiflow
  - universal-runbook-classification
  - universal-runbook-post-validation
  - universal-runbook-complete-callback
  - universal-chain-workflow
  - complete-nobootenv

The universal-runbook-during-flexiflow stage uses the parameter universal/runbook-during-flexiflow (a list of task names) as its task list. This is where you inject the work specific to your PE:

# Set the tasks to run during your runbook execution
drpcli profiles set global param universal/runbook-during-flexiflow \
    to '["my-install-task", "my-configure-task"]'

To build a new PE from this template:

1. Copy the universal-runbook workflow YAML, its stage YAMLs, and the associated classification and flexiflow parameter YAMLs from rackn/content/universal/content/
2. Rename every object: replace the universal-runbook prefix with your PE's name (e.g., my-app-deploy)
3. Rename the flexiflow parameter: universal/runbook-during-flexiflow → my-app-deploy/during-flexiflow
4. Write the tasks your PE needs and add their names to the my-app-deploy/during-flexiflow parameter default
5. Bundle workflow, stages, tasks, templates, and parameters into a single content pack YAML

The universal-runbook-classification, universal-runbook-complete-callback, and universal-chain-workflow stages can be referenced from universal as-is — they do not need to be renamed or copied.

Do not create bare workflows when a PE pattern exists — If a pipeline element already covers your phase, use the flexiflow injection points instead of creating a new workflow.