Custom Config Providers (Consul, Redis, AWS AppConfig)

In FastKitty, tenant feature flags and metadata are separated from database secrets.

Tenant configuration is managed via Config Providers, allowing you to change feature flags in real time (e.g. updating Spotify's max_daily_posts from 1 to 10) without restarting your FastAPI app or deploying new code.

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The Provider Interface

Every tenancy config provider implements BaseTenancyConfigProvider in config/tenancy_config.py:

from abc import ABC, abstractmethod
from schemas.tenancy import TenantConfig

class BaseTenancyConfigProvider(ABC):
    @abstractmethod
    async def get_tenant_config(self, tenant_id: str) -> TenantConfig | None:
        """Fetch metadata, display name, and feature flags for a single tenant."""
        ...

    @abstractmethod
    async def get_all_tenant_configs(self) -> dict[str, TenantConfig]:
        """Fetch all tenant configurations for startup validation."""
        ...

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Built-In Providers

Provider Name	Value in .env	Storage Location	Use Case
File Provider	TENANCY_CONFIG_PROVIDER=file	tenants_config.json	Local dev, static testing
Consul Provider	TENANCY_CONFIG_PROVIDER=consul	HashiCorp Consul KV	Distributed cloud configuration

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Writing a Custom Provider (e.g., Redis)

To store and hot-reload tenant feature flags using Redis:

1. Implement the Provider

In config/tenancy_config.py:

import json
import redis.asyncio as redis
from schemas.tenancy import TenantConfig
from config.tenancy_config import BaseTenancyConfigProvider

class RedisTenancyConfigProvider(BaseTenancyConfigProvider):
    def __init__(self, redis_url: str = "redis://localhost:6379/0") -> None:
        self.redis = redis.from_url(redis_url, decode_responses=True)

    async def get_tenant_config(self, tenant_id: str) -> TenantConfig | None:
        raw_data = await self.redis.get(f"fastkitty:tenant:{tenant_id}")
        if not raw_data:
            return None
        return TenantConfig.model_validate_json(raw_data)

    async def get_all_tenant_configs(self) -> dict[str, TenantConfig]:
        keys = await self.redis.keys("fastkitty:tenant:*")
        configs = {}
        for key in keys:
            tenant_id = key.split(":")[-1]
            raw_data = await self.redis.get(key)
            if raw_data:
                configs[tenant_id] = TenantConfig.model_validate_json(raw_data)
        return configs

2. Register & Configure

Register in config/tenancy_config.py and activate in .env:

TENANCY_CONFIG_PROVIDER=redis
REDIS_URL=redis://localhost:6379/0

Now, any changes made to a tenant's feature flags in Redis take effect immediately on subsequent requests!