/rsonnet-loki

Primary LanguageRust

TODO

env vars

Concepts

  • Exchange formats like YAML, JSON, etc are for machines, not humans. They are clunky, difficult to organize/parse/edit.
  • Configuration languages are an anti-pattern. They lack the expressiveness and integrations (lsps) of programming languages.
    • Rather than try to make another configuration language, use a programming language with good compiler guarantees, types, and editor integrations.
  • Derive behavior to minimize misconfiguration opportunities.

Patterns

Specification is cheap; don't bother with mutability. Much of this library is built on top of the Has<T> and With<T> traits.

In general, use Has<T> when you want an Option<T> and From<T> when you want <T>. I probably should have named that Might<T>...

Modules

builtin

These are k8s primitives

paras

There are concepts built on top of the primitives. They can be used to overlay the primitives and give an idiomatic approach to some behavior or operating pattern. Examples inlcude:

  • Using the name label in metadata for standardized selection like name=<component>
    • This same concept is used to name types (sts, deployments, svcs, etc)
    • We can derive compatible selectors (pvc mounts, svc targets, sts pod attachments, etc)
  • Hashing the configmap(s) a pod mounts and including that in the pod's annotations to force rollouts when the configmap changes
  • Building self-anti affinity rules so data nodes aren't scheduled together.
  • Mounting volumes into consistently named paths within a container.

lokirs

This is an example usage of the library which creates a Loki deployment

Notes

  • Is it preferrable to use conventions to wrap structures externally? We could with_config_hash any T: Has<ConfigMap> + Has<Name> + With<ConfigMap>, etc. Then, we'd only need to specify this extra code (or remember to specify it at all!) once at the end.
  • Good demo
    • Derive(Has<T>) when a field matches
    • PrimitiveStream rewrite, i.e. config hash all Has<Vec<ConfigMap>> that are output by the program without ever having to specify it.
      • Show how to define this behavior and test for it
    • PrimitiveStream validation, i.e. ensure the combined requests or limits for a pod exceed the node resources for a particular machine class.
      • show how to define this behavior and test for it.
    • Load a manifest dump and apply validations.
  • idea: should we get rid of Has<T> and use From and TryFrom instead?

TODO

  • Ensure With<T> replaces all possible <T>s
  • Validations to return Option<Error>
  • mapping fns prior to validations
    • Configmaps should have hash annotations
    • everything should use name labels
    • use anti-affinity everywhere
    • no two volumes can have the same name
  • opt-out for config hashing when the configmap is intended to live-reload.
    • Do this with metadata, similar to Name?