Plugins

grelmicro discovers Providers and Adapters through entry-point groups. A third-party package registers under these groups and resolves by short name, so grelmicro never has to depend on the vendor. First-party Providers and Adapters use the very same path: there is no special case.

The two groups

Group	Maps	Example
grelmicro.providers	a vendor short name to a Provider class	redis = "grelmicro.providers.redis:RedisProvider"
grelmicro.{kind}.adapters	a short name to an Adapter class for one component kind	redis = "grelmicro.coordination.redis:RedisLockAdapter"

A Provider covers the vendor axis: one Provider per vendor. An Adapter covers the algorithm axis within a kind, so several adapters can share one Provider (a Redis lock and a Redis cache both run on RedisProvider).

The component kinds are coordination, coordination.election, coordination.schedule, cache, ratelimiter, and circuitbreaker.

Publish a third-party adapter

Say you ship grelmicro-mongo with a Mongo-backed lock. Write the Provider and the Adapter, then declare them in your package's pyproject.toml:

[project.entry-points."grelmicro.providers"]
mongo = "grelmicro_mongo:MongoProvider"

[project.entry-points."grelmicro.coordination.adapters"]
mongo = "grelmicro_mongo:MongoLockAdapter"

Once your package is installed alongside grelmicro, the name mongo resolves through the same loader grelmicro uses for its own backends. Users wire it up exactly like a first-party backend:

from grelmicro import Grelmicro
from grelmicro.coordination import Coordination
from grelmicro_mongo import MongoProvider

mongo = MongoProvider("mongodb://localhost:27017")
micro = Grelmicro(uses=[Coordination(mongo)])

A worked skeleton lives in examples/third-party-adapter/.

How resolution works

Listing entry points never imports the target module. The module loads only when a name is resolved, so installing many vendor packages stays cheap. An unknown name raises ProviderNotRegisteredError or AdapterNotRegisteredError with the requested name and the names that are installed:

No coordination adapter registered as 'mongo' in the
'grelmicro.coordination.adapters' entry-point group. Available: kubernetes,
memory, postgres, redis, sqlite. Install the package that ships it, or check
the name.