monitoring.py

# connect to the monitoring service 
from google.cloud import monitoring_v3
from google.oauth2 import service_account
import time

credentials = service_account.Credentials.from_service_account_file('serving.json')
client = monitoring_v3.MetricServiceClient(credentials = credentials)
project_name = client.project_path('serving-268422')

# create a custom metric
descriptor = monitoring_v3.types.MetricDescriptor()
descriptor.type = 'custom.googleapis.com/serving/requests' 
descriptor.metric_kind = (monitoring_v3.enums.MetricDescriptor.MetricKind.GAUGE)
descriptor.value_type = (monitoring_v3.enums.MetricDescriptor.ValueType.DOUBLE)
descriptor.description = 'Model serving requests.'

# record a data point to the custom metric 
series = monitoring_v3.types.TimeSeries()
series.metric.type = 'custom.googleapis.com/serving/requests'
series.metric.labels['ip'] = "1.2.3.4"
point = series.points.add()
point.value.double_value = 50
now = time.time()
point.interval.end_time.seconds = int(now)
client.create_time_series(project_name, [series])