def discoverGGC()

in traffic-light-example-python/lightController.py [0:0]
60 lines of code
13 McCabe index (conditional complexity)

def discoverGGC(host, iotCAPath, certificatePath, privateKeyPath, clientId):
    # Progressive back off core
    backOffCore = ProgressiveBackOffCore()

    # Discover GGCs
    discoveryInfoProvider = DiscoveryInfoProvider()
    discoveryInfoProvider.configureEndpoint(host)
    discoveryInfoProvider.configureCredentials(iotCAPath, certificatePath, privateKeyPath)
    discoveryInfoProvider.configureTimeout(10)  # 10 sec
    print("Iot end point: " + host)
    print("Iot CA Path: " + iotCAPath)
    print("GGAD cert path: " + certificatePath)
    print("GGAD private key path: " + privateKeyPath)
    print("GGAD thing name : " + clientId)
    retryCount = MAX_DISCOVERY_RETRIES
    discovered = False
    groupCA = None
    coreInfo = None
    while retryCount != 0:
        try:
            discoveryInfo = discoveryInfoProvider.discover(clientId)
            caList = discoveryInfo.getAllCas()
            coreList = discoveryInfo.getAllCores()

            # In this example we have one core
            # So we only pick the first ca and core info
            groupId, ca = caList[0]
            coreInfo = coreList[0]
            print("Discovered GGC: " + coreInfo.coreThingArn + " from Group: " + groupId)
            hostAddr = ""

            # In this example Ip detector lambda is turned on which reports 
            # the GGC hostAddr to the CIS (Connectivity Information Service) that stores the
            # connectivity information for the AWS Greengrass core associated with your group.
            # This is the information used by discovery and the list of host addresses
            # could be outdated or wrong and you would normally want to 
            # validate it in a better way.
            # For simplicity, we will assume the first host address that looks like an ip
            # is the right one to connect to GGC. 
            # Note: this can also be set manually via the update-connectivity-info CLI 
            for addr in coreInfo.connectivityInfoList:
                hostAddr = addr.host
                if isIpAddress(hostAddr):
                    break
            
            print("Discovered GGC Host Address: " + hostAddr)
            print("Now we persist the connectivity/identity information...")
            groupCA = GROUP_PATH + CA_NAME
            ggcHostPath = GROUP_PATH + GGC_ADDR_NAME
            if not os.path.exists(GROUP_PATH):
                os.makedirs(GROUP_PATH)
            groupCAFile = open(groupCA, "w")
            groupCAFile.write(ca)
            groupCAFile.close()
            groupHostFile = open(ggcHostPath, "w")
            groupHostFile.write(hostAddr)
            groupHostFile.close()

            discovered = True
            print("Now proceed to the connecting flow...")
            break
        except DiscoveryInvalidRequestException as e:
            print("Invalid discovery request detected!")
            print("Type: " + str(type(e)))
            print("Error message: " + e.message)
            print("Stopping...")
            break
        except BaseException as e:
            print("Error in discovery!")
            print("Type: " + str(type(e)))
            print("Error message: " + e.message)
            retryCount -= 1
            print("\n"+str(retryCount) + "/" + str(MAX_DISCOVERY_RETRIES) + " retries left\n")
            print("Backing off...\n")
            backOffCore.backOff()

    if not discovered:
        print("Discovery failed after " + str(MAX_DISCOVERY_RETRIES) + " retries. Exiting...\n")
        sys.exit(-1)