123 lines
4.1 KiB
Python
123 lines
4.1 KiB
Python
import boto.rds2
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import logging
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from health.services import check_all_services
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logger = logging.getLogger(__name__)
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def get_healthchecker(app):
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""" Returns a HealthCheck instance for the given app. """
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return HealthCheck.get_checker(app)
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class HealthCheck(object):
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def __init__(self, app):
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self.app = app
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def check_instance(self):
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"""
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Conducts a check on this specific instance, returning a dict representing the HealthCheck
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output and a number indicating the health check response code.
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"""
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service_statuses = check_all_services(self.app)
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return self.get_instance_health(service_statuses)
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def check_endtoend(self):
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"""
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Conducts a check on all services, returning a dict representing the HealthCheck
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output and a number indicating the health check response code.
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"""
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service_statuses = check_all_services(self.app)
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return self.calculate_overall_health(service_statuses)
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def get_instance_health(self, service_statuses):
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"""
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For the given service statuses, returns a dict representing the HealthCheck
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output and a number indicating the health check response code. By default,
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this simply ensures that all services are reporting as healthy.
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"""
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return self.calculate_overall_health(service_statuses)
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def calculate_overall_health(self, service_statuses, skip=None, notes=None):
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""" Returns true if and only if all the given service statuses report as healthy. """
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is_healthy = True
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notes = notes or []
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for service_name in service_statuses:
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if skip and service_name in skip:
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notes.append('%s skipped in compute health' % service_name)
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continue
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is_healthy = is_healthy and service_statuses[service_name]
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data = {
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'services': service_statuses,
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'notes': notes,
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'is_testing': self.app.config['TESTING']
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}
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return (data, 200 if is_healthy else 503)
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@classmethod
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def get_checker(cls, app):
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name = app.config['HEALTH_CHECKER'][0]
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parameters = app.config['HEALTH_CHECKER'][1] or {}
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for subc in cls.__subclasses__():
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if subc.check_name() == name:
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return subc(app, **parameters)
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raise Exception('Unknown health check with name %s' % name)
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class LocalHealthCheck(HealthCheck):
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@classmethod
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def check_name(cls):
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return 'LocalHealthCheck'
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class ProductionHealthCheck(HealthCheck):
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def __init__(self, app, access_key, secret_key):
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super(ProductionHealthCheck, self).__init__(app)
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self.access_key = access_key
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self.secret_key = secret_key
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@classmethod
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def check_name(cls):
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return 'ProductionHealthCheck'
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def get_instance_health(self, service_statuses):
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# Note: We skip the redis check because if redis is down, we don't want ELB taking the
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# machines out of service. Redis is not considered a high avaliability-required service.
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skip = ['redis']
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notes = []
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# If the database is marked as unhealthy, check the status of RDS directly. If RDS is
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# reporting as available, then the problem is with this instance. Otherwise, the problem is
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# with RDS, and so we skip the DB status so we can keep this machine as 'healthy'.
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db_healthy = service_statuses['database']
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if not db_healthy:
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rds_status = self._get_rds_status()
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notes.append('DB reports unhealthy; RDS status: %s' % rds_status)
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# If the RDS is in any state but available, then we skip the DB check since it will
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# fail and bring down the instance.
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if rds_status != 'available':
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skip.append('database')
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return self.calculate_overall_health(service_statuses, skip=skip, notes=notes)
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def _get_rds_status(self):
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""" Returns the status of the RDS instance as reported by AWS. """
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try:
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region = boto.rds2.connect_to_region('us-east-1',
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aws_access_key_id=self.access_key, aws_secret_access_key=self.secret_key)
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response = region.describe_db_instances()['DescribeDBInstancesResponse']
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result = response['DescribeDBInstancesResult']
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instances = result['DBInstances']
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status = instances[0]['DBInstanceStatus']
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return status
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except:
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logger.exception("Exception while checking RDS status")
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return 'error'
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