What is Step Functions? What is it good for? When to use it? How does it work? Some tips and tricks

1. Delightful steps to becoming a
functioning user of
AWS Step Functions

3. orchestration service that allows you to
model workflows as state machines

4. design with JSON
https://states-language.net/spec.html

6. start a state machine via..
API Gateway CloudWatch Events
including cron
StepFunctions
.startExecution(req)
.promise()

8. state transitions

10. $25 PER MILLION

11. $25 PER MILLION
15X LAMBDA PRICING!

12. Pros Cons
$$$

13. Pros Cons
visual
$$$

14. Pros Cons
visual
$$$
error handling

15. Pros Cons
visual
$$$
error handling
audit

16. business critical workflows
what: stuff that makes money, e.g. payment and subscription flows
why: more robust error handling worth the premium

17. complex workflows
what: complex workflows that involves many states,
branching logic, etc.
why: visual workflow is a powerful design (for product)
and diagnostic tool (for CS)

19. long running workflows
what: workflows that cannot complete in five-minutes
(Lambda limit)
why: AWS discourages recursive Lambda functions, Step
Functions gives you explicit branching checks, and
can timeout at workflow level

20. Step Functions and the 7 types of states

21. "TaskState": {
"Type": "Task",
"Resource": "arn:aws:lambda:us-east-1:1234556788:function:hello-world",
"Next": "NextState",
"TimeoutSeconds": 300
}
Task
Executes a Lambda function.

22. "TaskState": {
"Type": "Task",
"Resource": "arn:aws:lambda:us-east-1:1234556788:function:hello-world",
"Next": "NextState",
"TimeoutSeconds": 300
}
Task
Executes a Lambda function.
Defaults to 60s, even if function has longer timeout

23. "TaskState": {
"Type": "Task",
"Resource": "arn:aws:lambda:us-east-1:1234556788:function:hello-world",
"Next": "NextState",
"TimeoutSeconds": 300
}
Task
Executes a Lambda function.
Defaults to 60s, even if function has longer timeout
Set this to match your function’s timeout

24. "NoOp": {
"Type": "Pass",
"Result": {
"is": 42
},
"ResultPath": "$.the_answer_to_the_question_of_life_the_universe_and_everything",
"Next": "NextState"
}
Pass
Passes input to output without doing any work.

25. Pass
Passes input to output without doing any work.
{ }
{
“the_answer_to_the_question_of_life_the_universe_and_everything”: {
“is”: 42
}
}

26. "WaitTenSeconds" : {
"Type" : "Wait",
"Seconds" : 10,
"Next": "NextState"
}
Wait
Wait before transitioning to next state.
"WaitTenSeconds" : {
"Type" : "Wait",
“Timestamp": "2018-08-08T01:59:00Z",
"Next": "NextState"
}

27. "WaitTenSeconds" : {
"Type" : "Wait",
"SecondsPath" : "$.waitTime",
"Next": "NextState"
}
Wait
Wait before transitioning to next state.
"WaitTenSeconds" : {
"Type" : "Wait",
“TimestampPath": “$.waitUntil”,
"Next": "NextState"
}

28. "SuccessState" : {
"Type" : "Succeed"
}
Succeed
Terminates the state machine successfully.

29. "FailState" : {
"Type" : “Fail",
"Error" : "TypeA",
"Cause" : "Kaiju Attack",
}
Fail
Terminates the state machine and mark it as failure.

30. "ChoiceState": {
"Type" : "Choice",
"Choices": [
{
"Variable": "$.name",
"StringEquals": "Neo"
"Next": "RedPill"
}
],
"Default": "BluePill"
}
Choice
Adds branching logic to the state machine.

31. "ChoiceState": {
"Type" : "Choice",
"Choices": [
{
"Variable": "$.name",
"StringEquals": "Neo"
"Next": "RedPill"
}
],
"Default": "BluePill"
}
Choice
Adds branching logic to the state machine.

32. "ChoiceState": {
"Type" : "Choice",
"Choices": [
{
"Variable": "$.name",
"StringEquals": "Neo"
"Next": "RedPill"
}
],
"Default": "BluePill"
}
Choice
Adds branching logic to the state machine.
{
“And”: [
{
"Variable": "$.name",
"StringEquals": “Cypher"
},
{
"Variable": "$.afterNeoIsRescued",
"BooleanEquals": true
},
],
"Next": "BluePill"
}

33. "FunWithMath": {
"Type": "Parallel",
"Branches": [
{
"StartAt": "Add",
"States": {
"Add": {
"Type": "Task",
"Resource": "arn:aws:lambda:us-east-1:1234556788:function:add",
"End": true
}
}
},
…
],
"Next": "NextState"
}
Parallel
Performs tasks in parallel.

34. managing state

35. { “x”: 42, “y”: 13 }
$ =>
{
“x”: 42,
“y”: 13
}
"choose": {
"Type": "Choice",
"Choices": [
{
"And": [
{
"Variable": "$.x",
"NumericGreaterThanEquals": 42
},
{
"Variable": "$.y",
"NumericLessThan": 42
}
],
"Next": "subtract"
}
],
"Default": "add"
},

36. { “x”: 42, “y”: 13 }
$ =>
{
“x”: 42,
“y”: 13
}
"subtract": {
"Type": "Task",
"Resource":"arn:aws:lambda:…",
"Next": "double",
"ResultPath": "$.n"
},

37. { “x”: 42, “y”: 13 }
$ =>
{
“x”: 42,
“y”: 13
}
module.exports.handler = (input, context, callback) => {
callback(null, input.x - input.y);
};
$.n

38. { “x”: 42, “y”: 13 }
$ =>
{
“x”: 42,
“y”: 13,
“n”: 29
}

39. { “x”: 42, “y”: 13 }
$ =>
{
“x”: 42,
“y”: 13,
“n”: 29
}
"double": {
"Type":"Task",
“Resource”:”arn:aws:lambda:...",
"InputPath":"$.n",
"End":true
}

40. { “x”: 42, “y”: 13 }
$ =>
{
“x”: 42,
“y”: 13,
“n”: 29
}
module.exports.handler = (input, context, callback) => {
callback(null, input * 2);
};
$.n
$

41. { “x”: 42, “y”: 13 }
{ “output”: 58 }

42. handling errors

43. http://amzn.to/2vL7nCR

44. http://amzn.to/2vL7nCR

45. http://amzn.to/2vL7nCR
default is 3
0 = never retried

46. http://amzn.to/2vL7nCR
each “Retrier” keeps track of…
…its own retry count

47. "Retry": [
{
"ErrorEquals": [ "ErrorA", "ErrorB" ],
"IntervalSeconds": 1,
"BackoffRate": 2.0,
"MaxAttempts": 2
},
{
"ErrorEquals": [ "ErrorC" ],
"IntervalSeconds": 5
}
],
0
0

48. "Retry": [
{
"ErrorEquals": [ "ErrorA", "ErrorB" ],
"IntervalSeconds": 1,
"BackoffRate": 2.0,
"MaxAttempts": 2
},
{
"ErrorEquals": [ "ErrorC" ],
"IntervalSeconds": 5
}
],
1
0
ErrorA

49. "Retry": [
{
"ErrorEquals": [ "ErrorA", "ErrorB" ],
"IntervalSeconds": 1,
"BackoffRate": 2.0,
"MaxAttempts": 2
},
{
"ErrorEquals": [ "ErrorC" ],
"IntervalSeconds": 5
}
],
2
0
ErrorA ErrorB

50. "Retry": [
{
"ErrorEquals": [ "ErrorA", "ErrorB" ],
"IntervalSeconds": 1,
"BackoffRate": 2.0,
"MaxAttempts": 2
},
{
"ErrorEquals": [ "ErrorC" ],
"IntervalSeconds": 5
}
],
2
1
ErrorA ErrorB ErrorC

51. "Retry": [
{
"ErrorEquals": [ "ErrorA", "ErrorB" ],
"IntervalSeconds": 1,
"BackoffRate": 2.0,
"MaxAttempts": 2
},
{
"ErrorEquals": [ "ErrorC" ],
"IntervalSeconds": 5
}
],
ErrorA ErrorB ErrorC ErrorB
2
1

52. http://amzn.to/2vL7nCR
all means of retry exhausted

53. monitoring/debugging

61. Wrapping multiple states in a try-catch
using Parallel states

62. catch-all error handling
special-case error
handling

63. special-case error
handling
catch-all error
handling

64. http://bit.ly/2MJprGx

65. Recursions

66. if ($.isComplete === true)
then NotifyResult
else ProcessS3File

69. Sagas

72. http://bit.ly/2N8Crm8

73. Semaphores

75. http://bit.ly/2Ln5bpr