Each custom service can provide a service advisor as a Python script named service-advisor.py in their service folder. A Service Advisor allows custom services to integrate into the stack advisor behavior which only applies to the services within the stack.
Service Advisor Inheritance
Unlike the Stack-advisor scripts, the service-advisor scripts do not automatically extend the parent service's service-advisor scripts. The service-advisor script needs to explicitly extend their parent's service service-advisor script. The following code sample shows how you would refer to a parent's service_advisor.py. In this case it is extending the root service-advisor.py file in the resources/stacks directory.
SCRIPT_DIR = os.path.dirname(os.path.abspath(__file__))
STACKS_DIR = os.path.join(SCRIPT_DIR, '../../../stacks/')
PARENT_FILE = os.path.join(STACKS_DIR, 'service_advisor.py')
try:
with open(PARENT_FILE, 'rb') as fp:
service_advisor = imp.load_module('service_advisor', fp, PARENT_FILE, ('.py', 'rb', imp.PY_SOURCE))
except Exception as e:
traceback.print_exc()
print "Failed to load parent"
class HAWQ200ServiceAdvisor(service_advisor.ServiceAdvisor):
Service Advisor Behavior
Like the stack advisors, service advisors provide information on 4 important aspects for the service:
- Recommend layout of the service on cluster
- Recommend service configurations
- Validate layout of the service on cluster
- Validate service configurations
By providing the service-advisor.py file, one can control dynamically each of the above for the service.
The main interface for the service-advisor scripts contains documentation on how each of the above are called, and what data is provided.
class ServiceAdvisor(DefaultStackAdvisor):
def colocateService(self, hostsComponentsMap, serviceComponents):
pass
def getServiceConfigurationRecommendations(self, configurations, clusterSummary, services, hosts):
pass
def getServiceComponentLayoutValidations(self, services, hosts):
return []
def getServiceConfigurationsValidationItems(self, configurations, recommendedDefaults, services, hosts):
return []