amazon-web-services - 如何修改 AWS Step 函数？

Question

从 AWS 控制台看来，AWS Step 函数是不可变的。有没有办法修改它？如果不是，版本控制如何工作？每次我必须对状态机进行增量更改时，我是否必须创建一个新的状态机？

Answer 1

根据这个论坛条目，目前还没有办法修改现有的状态机。您需要每次都创建一个新的。

Answer 2

这些天来，我一直在使用 CloudFormation w/ boto3。打算把它写在这里，因为过去我对 CloudFormation 有点害怕，但是通过一个端到端的例子，它可能更平易近人。

step_function_stack.yaml

AWSTemplateFormatVersion: '2010-09-09'
Transform: 'AWS::Serverless-2016-10-31'
Description: >-
  A description of the State Machine goes here. 
Resources:
  MyStateMachineName:
    Type: AWS::StepFunctions::StateMachine
    Properties:
      RoleArn: "arn:aws:iam::{{aws_account_id}}:role/service-role/StepFunctions-MyStepFunctionRole"

      StateMachineName: "MyStateMachineName"
      StateMachineType: "EXPRESS"

      DefinitionString:
        Fn::Sub: |
          {{full_json_definition}}

manage_step_functions.py

import boto3
import os
import time
from jinja2 import Environment


def do_render(full_json_definition):
    with open('step_function_stack.yaml') as fd:
        template = fd.read()
    yaml = Environment().from_string(template).render(
            full_json_definition=full_json_definition,
            aws_account_id=os.getenv('AWS_ACCOUNT_ID')) 
    return yaml


def update_step_function(stack_name, full_json_definition,):
    yaml = do_render(full_json_definition)
    client = boto3.client('cloudformation')
    response = client.update_stack(
        StackName=stack_name,
        TemplateBody=yaml,
        Capabilities=[
            'CAPABILITY_AUTO_EXPAND',
        ])
    return response


def create_step_function(stack_name, full_json_definition,):
    yaml = do_render(full_json_definition)
    client = boto3.client('cloudformation')
    response = client.update_stack(
        StackName=stack_name,
        TemplateBody=yaml,
        Capabilities=[
            'CAPABILITY_AUTO_EXPAND',
        ])
    return response
    

  def get_lambdas_stack_latest_events(stack_name):
      # Get the first 100 most recent events.
      client = boto3.client('cloudformation')
      return client.describe_stack_events(
          StackName=stack_name)


  def wait_on_update(stack_name):
      events = None
      while events is None or events['StackEvents'][0]['ResourceStatus'] not in ['UPDATE_COMPLETE',
              'UPDATE_ROLLBACK_COMPLETE', 'DELETE_COMPLETE', 'CREATE_COMPLETE']:

          print(events['StackEvents'][0]['ResourceStatus'] if events else ...)
          events = get_lambdas_stack_latest_events(stack_name)
          time.sleep(1)

      return events 

step_function_definition.json

{
  "Comment": "This is a Hello World State Machine from https://docs.aws.amazon.com/step-functions/latest/dg/getting-started.html#create-state-machine",
  "StartAt": "Hello",
  "States": {
    "Hello": {
      "Type": "Pass",
      "Result": "Hello",
      "Next": "World"
    },
    "World": {
      "Type": "Pass",
      "Result": "World",
      "End": true
    }
  }
}

创建阶跃函数

# From a python shell for example
# First just set any privileged variables through environmental variables so they are not checked into code
# export AWS_ACCOUNT_ID=999999999

# edit step_function_definition.json then read it
with open('step_function_definition.json') as fd:
    step_function_definition = fd.read()
    
import manage_step_functions as msf
stack_name = 'MyGloriousStepFuncStack'
msf.create_step_function(stack_name, step_function_definition)

如果您准备好更新您的状态机，您可以编辑step_function_definition.json或创建一个新文件以供参考，step_function_definition-2021-01-29.json. （因为在撰写本文时 Step Functions 没有像 Lambda 这样的版本）。

import manage_step_functions as msf
stack_name = 'MyGloriousStepFuncStack'
with open('step_function_definition-2021-01-29.json') as fd:
    step_function_definition = fd.read()

msf.update_step_function(stack_name, step_function_definition)

Answer 3

目前，您可以编辑状态 mashine。右上角的“编辑状态机”按钮