Yan Cui
I help clients go faster for less using serverless technologies.
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I never fully recovered my workspace setup when I upgraded my laptop two years ago, and I still miss things today. If only I had known about Gitpod back then…
I have some exciting news to share with you about the Serverless Step Functions plugin.
One of the main pain points of using the plugin was that you needed to use fully-formed ARNs. We addressed this in v1.18.0 by supporting CloudFormation intrinsic functions Fn:GetAtt
and Ref
. This makes it possible for you to reference a local function instead.
functions: hello-world: handler: hello-world.handler stepFunctions: stateMachines: myStateMachine: definition: StartAt: HelloWorld States: HelloWorld: Type: Task Resource: Fn::GetAtt: [HelloDashworldLambdaFunction, Arn] End: true
But this is still a leaky abstraction – you have to know how the Serverless framework converts local function names into CloudFormation logical IDs.
Newcomers would often get confused here.
“How did you get the logical ID
HelloDashworldLambdaFunction
fromhello-world
?”
I can hardly blame them for not knowing. This is an implementation detail in the Serverless framework, one that you shouldn’t have to care about!
Which is why I’m really happy to tell you that, as of v2.2.0 you can reference local functions using their local names in the state machine definition.
functions: hello-world: handler: hello-world.handler stepFunctions: stateMachines: myStateMachine: definition: StartAt: firstTask States: firstTask: Type: Task Resource: Fn::GetAtt: [hello-world, Arn] Next: secondTask secondTask: Type: Task Resource: arn:aws:states:::lambda:invoke Parameters: FunctionName: # you can use Ref to get the function name Ref: hello-world Payload: answer: 42 Next: thirdTask thirdTask: Type: Task Resource: arn:aws:states:::lambda:invoke.waitForTaskToken Parameters: FunctionName: # you can also use Fn::GetAtt to get the ARN Fn::GetAtt: [hello-world, Arn] Payload: token.$: $$.Task.Token End: true
In the above example, when we reference the local function hello-world
we no longer need to use its CloudFormation logical ID HelloDashworldLambdaFunction
.
As you can see from the example, it applies when you use either Ref
or Fn::GetAtt
functions in a Task
state. And it applies to all 3 ways of invoking a Lambda function from a Task
state.
Whenever you’re ready, here are 3 ways I can help you:
- Production-Ready Serverless: Join 20+ AWS Heroes & Community Builders and 1000+ other students in levelling up your serverless game. This is your one-stop shop for quickly levelling up your serverless skills.
- I help clients launch product ideas, improve their development processes and upskill their teams. If you’d like to work together, then let’s get in touch.
- Join my community on Discord, ask questions, and join the discussion on all things AWS and Serverless.