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Introduce parameters to control the connection pool for engine creation #14

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Merged
merged 5 commits into from
Mar 19, 2025
Merged

Introduce parameters to control the connection pool for engine creation #14

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c9f7073
Introduce parameters to control the connection pool for engine creation
danceb Mar 13, 2025
f41bbae
Connection pool parameters using ENV
danceb Mar 14, 2025
094e5a2
Set ENV default values directly and revert misleading use of db_engin…
danceb Mar 17, 2025
b89ca6a
Remove obsolete docstring
manisandro Mar 19, 2025
5c8d0b2
Update database.py
manisandro Mar 19, 2025
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4 changes: 4 additions & 0 deletions README.md
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Original file line number Diff line number Diff line change
Expand Up @@ -24,6 +24,10 @@ Environment variables
| `TENANT_HEADER` | `<empty>` | The name of the HTTP header which contains the tenant name for multi-tenant setups. |
| `TENANT_PATH_PREFIX` | `@service_prefix@/@tenant@` | URL path prefix for all QWC services for multi-tenant setups. |
| `TENANT_ACCESS_COOKIE_PATH` | `<tenant_path_prefix>` | Path for which the access cookie is valid for multi-tenant setups. |
| `POOL_SIZE` | `5` | Maximum number of possible data base connections. |
| `MAX_OVERFLOW` | `10` | Additional connections beyond pool_size during peak load. |
| `POOL_TIMEOUT` | `30` | Time (in seconds) to wait for a connection to become available. |
| `POOL_RECYCLE` | `-1` | Time (in seconds) after idle connections will be resetted. |

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===========
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18 changes: 15 additions & 3 deletions qwc_services_core/database.py
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@@ -1,7 +1,7 @@
import os

from sqlalchemy import create_engine

from sqlalchemy.pool import QueuePool

class DatabaseEngine():
"""Helper for database connections using SQLAlchemy engines"""
Expand All @@ -15,12 +15,24 @@ def db_engine(self, conn_str):

:param str conn_str: DB connection string for SQLAlchemy engine

see http://docs.sqlalchemy.org/en/latest/core/engines.html#postgresql
see https://docs.sqlalchemy.org/en/latest/core/engines.html#postgresql
"""

db_pool_size = os.environ.get('POOL_SIZE', 5)
db_max_overflow = os.environ.get('MAX_OVERFLOW', 10)
db_pool_timeout = os.environ.get('POOL_TIMEOUT', 30)
db_pool_recycle = os.environ.get('POOL_RECYCLE', -1)

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@manisandro manisandro Mar 15, 2025

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I'd set the default values directly here and remove them from the db_engine args.

Also, self.db_engine_var does not return an environment variable value, but invokes self.db_engine to return a DB Engine configured with the connections string as configured in the specified environment variable. Use os.environ.get here.

engine = self.engines.get(conn_str)
if not engine:
engine = create_engine(
conn_str, pool_pre_ping=True, echo=False)
conn_str,
poolclass=QueuePool,
pool_size=db_pool_size,
max_overflow=db_max_overflow,
pool_timeout=db_pool_timeout,
pool_recycle=db_pool_recycle,
pool_pre_ping=True, echo=False)
self.engines[conn_str] = engine
return engine

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