Refreshable Cache - bakefile

RefreshableCacheRegistry is a standalone refreshable cache for secrets or any fetched values, usable in any Python project with no Bakebook required. Subclass FetchFn to declare how a value is fetched, register it under a key, and the first get fetches and caches it:

from dataclasses import dataclass

from bakelib.refreshable_cache import FetchFn, KeyringCache, MemoryCache, RefreshableCacheRegistry


@dataclass(frozen=True)
class GcpSecretFetchFn(FetchFn[str]):
    project_id: str
    secret_id: str

    def __call__(self) -> str:
        # Real implementation calls the GCP Secret Manager API here
        return "dummy-secret-value"


registry = RefreshableCacheRegistry[str](namespace="myapp", backends=[MemoryCache, KeyringCache])
registry.insert_cache(
    "api_key",
    fetch_fn=GcpSecretFetchFn(key="api_key", project_id="my-project", secret_id="api-key"),
)

registry.get("api_key")  # fetches and caches on first call
registry.refresh("api_key")  # force a re-fetch
registry.has_value("api_key")  # True once cached

Refreshing rotated secrets

For secrets rotated while your process runs, wrap the call in @cache.catch_refresh and raise RefreshNeededError when the service rejects the cached value:

cache = registry.get_cache("api_key")


@cache.catch_refresh
def call_api() -> str:
    token = cache.get()
    response = api_request(token)  # your code
    if response.status == 401:  # token rejected (rotated server-side)
        raise cache.RefreshNeededError
    return response.body

The cache then clears and call_api retries, re-fetching a fresh token via cache.get(). Retries are tenacity-backed (stop/wait, defaults 2 attempts, no delay), so secrets refresh at runtime with no restart. acatch_refresh is the async variant.

Backends

MemoryCache - default, ephemeral
KeyringCache - system keyring, persistent
ChainedCache - several backends, read-first/write-all
NullCache - disabled

A single backend is used directly, multiple are wrapped in ChainedCache. Pass ttl= for expiry. Secrets wires this registry into a Bakebook with bake secret commands.

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