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Updated on 2024-05-09 GMT+08:00
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Developing an Event Function

Function Syntax

You are advised to use Python 3.6.

FunctionGraph supports Python 2.7, Python 3.6, and Python 3.9.

Syntax for creating a handler function in Python:

def handler (event, context)

  • handler: name of the function that FunctionGraph invokes to execute your code. The name must be consistent with that you define when creating a function.
  • event: event parameter defined for the function. The parameter is in JSON format.
  • Context: runtime information provided for executing the function. For details, see SDK APIs.

Python Initializer

FunctionGraph supports the following Python runtimes:

  • Python 2.7 (runtime = python2.7)
  • Python 3.6 (runtime = python3)
  • Python 3.9 (runtime = python3)

Initializer syntax:

[File name].[Initializer name]

For example, if the initializer is named main.my_initializer, FunctionGraph loads the my_initializer function defined in the main.py file.

To use Python to build initialization logic, define a Python function as the initializer. The following is a simple initializer (Python 2.7 is used as an example):

def my_initializer(context):
    print 'hello world!'
  • Function Name

    The function name my_initializer must be the initializer function name specified for a function. For example, if the initializer is named main.my_initializer, FunctionGraph loads the my_initializer function defined in the main.py file.

  • context

    The context parameter contains the runtime information about a function. For example, request ID, temporary AK, and function metadata.

SDK APIs

Table 1 describes the context methods provided by FunctionGraph.

Table 1 Context methods

Method

Description

getRequestID()

Obtains a request ID.

getRemainingTimeInMilliSeconds ()

Obtains the remaining running time of a function.

getAccessKey()

Obtains the AK (valid for 24 hours) with an agency. If you use this method, you need to configure an agency for the function.

NOTE:

FunctionGraph has stopped maintaining the getAccessKey API in the Runtime SDK. You cannot use this API to obtain a temporary AK.

getSecretKey()

Obtains the SK (valid for 24 hours) with an agency. If you use this method, you need to configure an agency for the function.

NOTE:

FunctionGraph has stopped maintaining the getSecretKey API in the Runtime SDK. You cannot use this API to obtain a temporary SK.

getSecurityAccessKey()

Obtains the SecurityAccessKey (valid for 24 hours) with an agency. If you use this method, you need to configure an agency for the function.

getSecuritySecretKey()

Obtains the SecuritySecretKey (valid for 24 hours) with an agency. If you use this method, you need to configure an agency for the function.

getSecurityToken()

Obtains the SecurityToken (valid for 24 hours) with an agency. If you use this method, you need to configure an agency for the function.

getUserData(string key)

Uses keys to obtain the values passed by environment variables.

getFunctionName()

Obtains the name of a function.

getRunningTimeInSeconds ()

Obtains the timeout of a function.

getVersion()

Obtains the version of a function.

getMemorySize()

Obtains the allocated memory.

getCPUNumber()

CPU usage of a function.

getPackage()

Obtains a function group, that is, an app.

getToken()

Obtains the token (valid for 24 hours) with an agency. If you use this method, you need to configure an agency for the function.

getLogger()

Obtains the logger method provided by the context and returns a log output class. Logs are output in the format of Time-Request ID-Content by using the info method.

For example, use the info method to output logs:

log = context.getLogger()

log.info("test")

getAlias

Obtains function alias.

Results returned by using the getToken(), getAccessKey(), and getSecretKey() methods contain sensitive information. Exercise caution when using these methods.

Execution Result

The execution result consists of the function output, summary, and log output.

Table 2 Description of the execution result

Parameter

Successful Execution

Failed Execution

Function Output

The defined function output information is returned.

A JSON file that contains errorMessage, errorType, and stackTrace is returned. The format is as follows:

{
    "errorMessage": "",
    "errorType": "",
    "stackTrace": []
}

errorMessage: Error message returned by the runtime.

errorType: Error type.

stackTrace: Stack error information returned by the runtime.

Summary

Request ID, Memory Configured, Execution Duration, Memory Used, and Billed Duration are displayed.

Request ID, Memory Configured, Execution Duration, Memory Used, and Billed Duration are displayed.

Log Output

Function logs are printed. A maximum of 4 KB logs can be displayed.

Error information is printed. A maximum of 4 KB logs can be displayed.
Parent topic: Python