Close readpool only if it exists

[vprivat-ads]

Description:

When we launch stac-fastapi-pgstac with invalid postgresql credentials, the readpool will not be created, but our application will try to close it and raise this exception:

asyncpg.exceptions.InvalidPasswordError: password authentication failed for user "catalog"
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
  File "/usr/local/lib/python3.11/site-packages/starlette/datastructures.py", line 685, in __getattr__
    return self._state[key]
           ~~~~~~~~~~~^^^^^
KeyError: 'readpool'
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
  File "/usr/local/lib/python3.11/site-packages/starlette/routing.py", line 694, in lifespan
    async with self.lifespan_context(app) as maybe_state:
  File "/usr/local/lib/python3.11/contextlib.py", line 210, in __aenter__
    return await anext(self.gen)
           ^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/site-packages/rs_server_catalog/app.py", line 168, in lifespan
    await close_db_connection(my_app)
  File "/usr/local/lib/python3.11/site-packages/stac_fastapi/pgstac/db.py", line 86, in close_db_connection
    await app.state.readpool.close()
          ^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/site-packages/starlette/datastructures.py", line 688, in __getattr__
    raise AttributeError(message.format(self.__class__.__name__, key))
AttributeError: 'State' object has no attribute 'readpool'
ERROR:    Application startup failed. Exiting.

PR Checklist:

• pre-commit hooks pass locally
• Tests pass (run make test)
• Documentation has been updated to reflect changes, if applicable, and docs build successfully (run make docs)
• Changes are added to the CHANGELOG.

[vincentsarago]

@vprivat-ads I can't replicate locally, my application exit silently.

On my local env, the app will tell Application startup failed. Exiting and exit directly.

asyncpg.exceptions.InvalidCatalogNameError: database "postgisyo" does not exist

ERROR:    Application startup failed. Exiting.

and thus won't perform the close_db_connection step

[vprivat-ads]

Maybe it happens only with custom lifespans, we currently have this in our application:

from stac_fastapi.pgstac.app import with_transactions
from stac_fastapi.pgstac.db import close_db_connection, connect_to_db

@asynccontextmanager
async def lifespan(my_app: FastAPI):
    """The lifespan function."""
    try:
        # Connect to the databse
        db_info = f"'{env['POSTGRES_USER']}@{env['POSTGRES_HOST']}:{env['POSTGRES_PORT']}'"
        while True:
            try:
                await connect_to_db(my_app, add_write_connection_pool=with_transactions)
                logger.info("Reached %r database on %s", env["POSTGRES_DB"], db_info)
                break
            except ConnectionRefusedError:
                logger.warning("Trying to reach %r database on %s", env["POSTGRES_DB"], db_info)

                # timeout gestion if specified
                if my_app.state.pg_timeout is not None:
                    my_app.state.pg_timeout -= my_app.state.pg_pause
                    if my_app.state.pg_timeout < 0:
                        sys.exit("Unable to start up catalog service")
                await asyncio.sleep(my_app.state.pg_pause)

        common_settings.set_http_client(httpx.AsyncClient(timeout=DEFAULT_TIMEOUT_CONFIG))

        # Run the data lifecycle management as an automatic periodic task
        lifecycle.run()

        yield

    finally:
        await lifecycle.cancel()
        await close_db_connection(my_app)
        await common_settings.del_http_client()

[vincentsarago]

Yeah, I think it's because you have a Try/Finally block. if an exception is raised before the yield, you'll still go to the close_db_connection while with the normal lifespan function we won't call it.

I'll approve the PR because it's technically correct 😅