Boot pipeline unit type


💊 Check boot prescription pipeline unit for a higher-level abstraction.

A very first pipeline unit is called “boot”. As the name suggests it is started as a first pipeline unit in the resolution pipeline. It’s main purpose is to check input, adjust input parameters, halt resolver in case of any undesired conditions or to print any messages to logger (that will show up in user logs). As in case of all units, it has access to resolver context to check any input values to the resolver (user input, parameters or hyperparameters).


Each boot pipeline unit is called just once per resolution before the stack generation pipeline is started.

Main usage

  • Adjust input parameters to the resolution process

  • Halt resolver before any stack resolution is done based on input values

    • Any exception raised will halt adviser with an error message (created out of exception message) populated to the adviser JSON result except for eager stopping (see bellow)

  • Print information into logs using logging

    • Any information logged will show up in adviser run logs - logging respects log-level configuration which was set up during adviser startup based on request/adviser configuration

  • Prematurely end resolution based on the the final state reached

Real world examples

  • Any adjustments to input parameters done can result in a logged messages

    • If a user uses a Python package index in the Pipfile that was not enabled by Thoth administrator a boot unit can adjust Pipfile (e.g. remove Python package index) - this configuration change will be propagated Thoth’s response in all integrations

    • If a user uses hardware (CPU/GPU) that is not known to Thoth’s knowledge base, a boot unit can adjust this information (remove it completelly or, for example, find a similar GPU model for recommendations) and print an informative log message

  • Adding messages to stack info (e.g. prescription version used)

  • Gate an application build in the cluster based on configured Python package indexes

    • If a user uses a Python package index that was not enabled by Thoth administrator in the Pipfile a boot unit can raise an exception causing a halt

  • Halting adviser in case of not sufficient runtime or buildtime information

    • If a user uses hardware (CPU/GPU) that is not known to Thoth’s knowledge base, a boot unit can halt adviser

Triggering unit for a specific package

To help with scaling the recommendation engine when it comes to number of pipeline units possibly registered, it is a good practice to state to which package the given unit corresponds. To run the pipeline unit for a specific package, this fact should be reflected in the pipeline unit configuration by stating package_name configuration option. An example can be a pipeline unit specific for TensorFlow packages, which should state package_name: "tensorflow" in the pipeline configuration.

If the pipeline unit is generic for any package, the package_name configuration has to default to None.

An example implementation

import logging

from thoth.adviser import Boot

_LOGGER = logging.getLogger(__name__)

class ExampleBoot(Boot):
    """This is an example boot implementation."""

  CONFIGURATION_DEFAULT: Dict[str, Any] = {"package_name": None}  # The pipeline unit is not specific to any package.

  def run(self) -> None:
      """Main entry-point for boot unit to demonstrate boot example."""
      cpu_family = self.context.project.runtime_environment.hardware.cpu_family

      if cpu_family is not None
          known_cpu_families = self.context.graph.get_cpu_family_all()
          if cpu_family not in known_cpu_families:
                  "CPU family used %s is not known, it will not be considered"
              self.context.project.runtime_environment.hardware.cpu_family = None
              # Or you can raise an exception causing adviser halt:
              #  raise ValueError(f"CPU family used {cpu_family!r} is not known")

The implementation can also provide other methods, such as Unit.pre_run, Unit.post_run or Unit.post_run_report and pipeline unit configuration adjustment. See unit documentation for more info.