PB-1992 : Add gunicorn keepalive env var

Author: Sami Nouidri

README.md

@@ -193,3 +193,4 @@ The service is configured by Environment Variable:
 | GUNICORN_TMPFS_DIR | `None` |The working directory for the gunicorn workers. |
 | WSGI_WORKERS | `2` | The number of workers per CPU. | 
 | UNLISTED_ICON_SETS | | Comma separated list of icon set to un-list. Those sets won't be listed in the /sets endpoint.  |
+| GUNICORN_KEEPALIVE | `2` | The [`keepalive`](https://docs.gunicorn.org/en/stable/settings.html#keepalive) setting passed to gunicorn. |

app/settings.py

@@ -28,6 +28,8 @@
 os.environ['LOGS_DIR'] = LOGS_DIR  # Set default if not set
 LOGGING_CFG = os.getenv('LOGGING_CFG', 'logging-cfg-local.yml')
 
+GUNICORN_KEEPALIVE = int(os.getenv('GUNICORN_KEEPALIVE', '2'))
+
 # Definition of the allowed domains for CORS implementation
 ALLOWED_DOMAINS = os.getenv('ALLOWED_DOMAINS', r'.*').split(',')
 CACHE_CONTROL = os.getenv('CACHE_CONTROL', 'public, max-age=86400')

wsgi.py

@@ -4,6 +4,7 @@
 
 from app import app as application
 from app.helpers import get_logging_cfg
+from app.settings import GUNICORN_KEEPALIVE
 
 
 class StandaloneApplication(BaseApplication):  # pylint: disable=abstract-method
@@ -36,6 +37,7 @@ def load(self):
         'workers': int(os.getenv('WSGI_WORKERS',
                                  '2')),  # scaling horizontally is left to Kubernetes
         'timeout': int(os.getenv('WSGI_TIMEOUT', '5')),
+        'keepalive': GUNICORN_KEEPALIVE,
         'logconfig_dict': get_logging_cfg(),
         'forwarded_allow_ips': os.getenv('FORWARED_ALLOW_IPS', '*'),
         'secure_scheme_headers': {