without-configmap

A without behavior source backed by a Kubernetes ConfigMap mount: the first context that actually changes, proving the context-updated-by-a-stream half of the model end to end. Where without-env loads a static value once, this one re-parses on every mount change. See the without_configmap API reference for the full surface.

watch_config(mount, parse) is a Stream that yields the parsed config now and a freshly parsed value every time the mount changes. It watches the mount directory, not the file, so it catches the atomic ..data symlink swap that projected ConfigMaps use (a naive watch on the file alone misses those updates). read_yaml_file(Model, "config.yaml") is the usual parse: it reads one YAML file from the mount and validates it into a pydantic model.

Feed the stream through without.sample to read the latest value as a Context:

from pathlib import Path

from pydantic import BaseModel
from without import sample
from without_configmap import read_yaml_file, watch_config


class MyConfig(BaseModel):
    model_config = {"frozen": True}
    default_mode: str
    max_bytes: int


source = watch_config(Path("/etc/config"), read_yaml_file(MyConfig, "config.yaml"))
async with sample(source) as config:
    config.current()       # always the latest reloaded value, never blocks
    await config.updated() # block until the next reload lands, then return it

sample reads the first value eagerly, so the context is never "not ready"; a background task keeps it current for the life of the with block. current reads the latest value without blocking; updated is the deterministic counterpart that waits for the next reload to land (it inherits latest-wins, so it signals "the config moved on" rather than replaying every intermediate value). A reload whose YAML fails validation raises from the watch loop rather than silently serving a stale or partial value. Snapshot config.current() once per request or connection so a mid-flight reload does not change a value an in-progress handler already read.