Template Wiring

deps.py is the single assembly point in every OpenFrame template. It reads env vars via settings, constructs the adapter, and wraps it with TracingProxy. The service layer never sees a driver import.

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Wiring Sequence

sequenceDiagram
    participant E as Environment vars
    participant S as AdapterSettings
    participant A as Adapter
    participant TP as TracingProxy
    participant D as deps.py

    D->>S: PostgresSettings()
    S->>E: read DATABASE_URL, POOL_SIZE, CONNECTION_TIMEOUT
    S-->>D: validated settings
    D->>A: PostgresRepository(settings)
    A-->>D: repository instance
    D->>TP: TracingProxy(repo, prefix="repository.item")
    TP-->>D: traced repository
    D-->>D: cached via lru_cache or FastAPI Depends

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Pattern in Code

Every template's deps.py follows this structure. The adapter package name changes; the pattern does not.

from functools import lru_cache
from openframe.core.tracing import TracingProxy
from openframe.adapters.db.postgres import PostgresRepository, PostgresSettings

@lru_cache(maxsize=1)
def _get_settings() -> PostgresSettings:
    return PostgresSettings()   # reads env vars, raises ValidationError if missing

@lru_cache(maxsize=1)
def _get_repository() -> PostgresRepository:
    return PostgresRepository(_get_settings())

def get_repository() -> TracingProxy:
    return TracingProxy(_get_repository(), prefix="repository.item")

Note

lru_cache on the settings and repository means they are constructed once per process. get_repository() (without cache) returns a new TracingProxy wrapper each time, but the underlying repository is shared — the proxy is stateless.

→ See ports module for BaseRepository contract. → See tracing module for TracingProxy implementation.