pytemplatize 0.0.5

Sprinkling imperative logic into your template generation process.

Templatizer

Templatizer allows for sprinkling in some imperative logic to your declarative configuration files.

Why Imperative?

While a fully declarative configuration file is often nice to be able to describe the intended state of the world in a single place, these can also become quite verbose over time.

For Kubernetes, for example, you might be configuring a number of monitoring jobs. These will have different storage, CPU, and memory requirements. They also have unique configuration requirements for each one. I might be holding it wrong, but I find this very hard to make work in Helm and Kustomize without repeating myself over and over again.

What I want is something that runs before Helm, Kustomize, and whatever other tools you're using. I want something to generate files with the ability to do imperative logic first.

Example

import templatizer

class Simple(templatizer.Templatable):
    prop = 12345

class Imperative(templatizer.Templatable):
    tick = 0

    def prop(self):
        return 12345 + self.tick

simple = Simple()
assert simple.propval('prop') == 12345

imperative = Imperative()
assert imperative.propval('prop') == 12345
imperative.tick = 1
assert imperative.propval('prop') == 12346

The templatizer.run function takes a list of Templatable objects, generates them into strings, and adds separators in between. By default the --- separator is used, which is useful for generating YAML documents. This can be changed to suit your use case.

Kubernetes

The templatizer.k8s module includes generated definitions from the Kubernetes OpenAPI Spec.

This allows for generating Kubernetes manifests with imperative hooks. Examples of this are provided in the examples/ directory.