Python Serverless Tracer API

This page describes how to use the Python Serverless Tracer API to modify the behavior of the tracer within your AWS Lambda function.

Create Exit Calls

Exit calls are automatically instrumented for HTTP, Amazon DynamoDB, and inter-AWS Lambda calls. All other protocols need to manually create an exit call. 

To create an exit call, use the ExitCallContextManager method in a with statement to wrap the exit call. The method takes the following required parameters:

• exit_point_type: Type of the exit call

• exit_point_sub_type: Subtype of the exit call

• identifying_properties: Properties defining the exit call

The ExitCallContextManager method automatically reports any runtime exceptions that occur within the method's scope as exit call errors.

The code sample below demonstrates how to use the exit call method for a MySQL database:

import appdynamics # Add AppDynamics libraries. Must be the first line of code

@appdynamics.tracer
def handler(event, context):
    with appdynamics.ExitCallContextManager(exit_point_type="DB", exit_point_sub_type="DB", identifying_properties={"VENDOR": "MYSQL"}) as ec:
        data = fetch_from_db()

Exit Call Types and Identifying Properties

In the Controller, each exit call has a distinct type, determined by a set of identifying properties. Include at least one identifying property for each exit call type. 

 The exitCall types, subtypes, and identifying properties are listed below. For exit call subtypes, you can use the examples listed in the table or use an empty string.  

The following interceptors are supported and do not require manual instrumentation:

• Boto client:
  • Lambda: invoke, invokeAsync
  • DynamoDB: batch_get_item, batch_write_item, create_table, delete_table, delete_item, get_item, put_item, update_item
• Tornado
• http libraries

Create Exit Call Error Reports

The ExitCallContextManager method automatically reports errors. If you want to add custom error reports, use the report_exit_call_error method. The method takes the following parameters:

• error_name: Name of the error
• error_message (Optional): Descriptive error message
• http_status_code (Optional): The HTTP status code if available.

The code sample below demonstrates how you can use the exit call error report method:

import appdynamics 
@appdynamics.tracer 
def handler(event, context): 
	#Create an exit call 
    with appdynamics.ExitCallContextManager("DB", "DB", {"HOST": "ec2-12-123-123-12.us-west-2.compute.amazonaws.com", "PORT": "3306", "DATABASE": "movies", "VENDOR": "MYSQL"}) as ec:
        movies = fetch_movies_from_mysql_db()
        if movies == None:
			#Create an exit call error report 
            ec.report_exit_call_error(error_name="DBError", error_message="Item not found") #ec is the object returned by ExitCallContextManager above

Create Transaction Error Reports

By default, the Python Tracer automatically detects transaction error reports. You can customize these error reports using the appdynamics.report_error(error_name: str, error_message: str) method to report transaction errors. The method takes the following parameters:

• error_name: Name of the error

• error_message (Optional): Descriptive error message

The code sample below demonstrates how you can use the transaction error report method:

import appdynamics # Add AppDynamics libraries. Must be the first line of code
import requests #Add request library 

@appdynamics.tracer # Must come before the handler function
def my_handler(event, context):
	try:
        r = requests.get('https://api.github.com/events')
    except Exception as e:
        appdynamics.report_error(error_name=type(e).__name__, error_message=str(e)) # Reports a transaction error