kraken-core 0.2.4

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kraken-core

The kraken.core package provides the primitives of describing a build and deriving build tasks.

Aside from the kraken.core package, this package also provides the kraken.api module that is used only at runtime by Kraken build scripts and the kraken.testing module for Pytest fixtures.

How does it work?

Kraken uses tasks to describe units of work that can be chained and establish dependencies between each other. Each task has a schema that defines its input and output properties. When an output property is linked to the input property of another task, this established as dependency between the tasks.

from kraken.std.docker_gen import generate_dockerfile
from kraken.std.docker_build import build_docker_image
dockerfile = generate_dockerfile(source_file="Dockerfile.yml")
build_docker_image(dockerfile=dockerfile.path, tags=["example:latest"], load=True)

This populates the project with two tasks and connects the computed output property of one to the other, allowing the tasks that will run for build_docker_image() to pick up the dynamically generated Dockerfile that is written into a location in the build directory by the generate_dockerfile() task.

Core API

Kraken tasks are described with a schema. Each schema field has a type and may be an input or output parameter. Output parameters are only available once a resource is executed; Kraken will that a proper execution order is established such that output properties are hydrated before another resource tries to access them as an input.

from kraken.core.task import Context, Task, Property, Output, task_factory
from typing_extensions import Annotated

class GenerateDockerfileTask(Task):
    source_file: Property[str]
    path: Annotated[Property[str], Output]

    def execute(self, ctx: Context) -> None:
        path = Path(self.path.setdefault(str(ctx.build_directory / "Dockerfile")))
        path.write_text(render_dockerfile(Path(self.source_file.get()).read_text()))

generate_dockerfile = task_factory(GenerateDockerfileTask)