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feat(stepfunctions-tasks): evaluate expression as a task construct (#…
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…8555)

Replacement for the current implementation of experimental Evaluate Expression.
Merges state and service integration properties and represents them as a
construct.

Note that the changes to test are only the reordering of elements.
Re-ran the integration test and verified that it functions as documented.

BREAKING CHANGE:
`EvaluateExpression` is now a construct representing a task state rather than an embedded property called `task`

----

*By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license*
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@shivlaks
shivlaks committed Jun 29, 2020
1 parent d1c2ef2 commit 83fd2ae
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Showing 5 changed files with 64 additions and 69 deletions.
21 changes: 9 additions & 12 deletions packages/@aws-cdk/aws-stepfunctions-tasks/README.md
View file
Expand Up @@ -164,25 +164,22 @@ Use the `EvaluateExpression` to perform simple operations referencing state path
Example: convert a wait time from milliseconds to seconds, concat this in a message and wait:

```ts
const convertToSeconds = new sfn.Task(this, 'Convert to seconds', {
task: new tasks.EvaluateExpression({ expression: '$.waitMilliseconds / 1000' }),
resultPath: '$.waitSeconds'
const convertToSeconds = new tasks.EvaluateExpression(this, 'Convert to seconds', {
expression: '$.waitMilliseconds / 1000',
resultPath: '$.waitSeconds',
});

const createMessage = new sfn.Task(this, 'Create message', {
const createMessage = new tasks.EvaluateExpression(this, 'Create message', {
// Note: this is a string inside a string.
task: new tasks.EvaluateExpression({
expression: '`Now waiting ${$.waitSeconds} seconds...`',
runtime: lambda.Runtime.NODEJS_10_X,
}),
resultPath: '$.message'
resultPath: '$.message',
});

const publishMessage = new sfn.Task(this, 'Publish message', {
task: new tasks.PublishToTopic(topic, {
message: sfn.TaskInput.fromDataAt('$.message'),
}),
resultPath: '$.sns'
const publishMessage = new tasks.SnsPublish(this, 'Publish message', {
topic,
message: sfn.TaskInput.fromDataAt('$.message'),
resultPath: '$.sns',
});

const wait = new sfn.Wait(this, 'Wait', {
Expand Down
36 changes: 24 additions & 12 deletions packages/@aws-cdk/aws-stepfunctions-tasks/lib/evaluate-expression.ts
View file
Expand Up @@ -9,7 +9,7 @@ import * as path from 'path';
*
* @experimental
*/
export interface EvaluateExpressionProps {
export interface EvaluateExpressionProps extends sfn.TaskStateBaseProps {
/**
* The expression to evaluate. The expression may contain state paths.
*
Expand Down Expand Up @@ -49,11 +49,29 @@ export interface Event {
*
* @experimental
*/
export class EvaluateExpression implements sfn.IStepFunctionsTask {
constructor(private readonly props: EvaluateExpressionProps) {
export class EvaluateExpression extends sfn.TaskStateBase {
protected readonly taskMetrics?: sfn.TaskMetricsConfig;
protected readonly taskPolicies?: iam.PolicyStatement[];

private readonly evalFn: lambda.SingletonFunction;

constructor(scope: cdk.Construct, id: string, private readonly props: EvaluateExpressionProps) {
super(scope, id, props);

this.evalFn = createEvalFn(this.props.runtime || lambda.Runtime.NODEJS_10_X, this);

this.taskPolicies = [
new iam.PolicyStatement({
resources: [this.evalFn.functionArn],
actions: ['lambda:InvokeFunction'],
}),
];
}

public bind(task: sfn.Task): sfn.StepFunctionsTaskConfig {
/**
* @internal
*/
protected _renderTask(): any {
const matches = this.props.expression.match(/\$[.\[][.a-zA-Z[\]0-9]+/g);

let expressionAttributeValues = {};
Expand All @@ -67,19 +85,13 @@ export class EvaluateExpression implements sfn.IStepFunctionsTask {
);
}

const evalFn = createEvalFn(this.props.runtime || lambda.Runtime.NODEJS_10_X, task);

const parameters: Event = {
expression: this.props.expression,
expressionAttributeValues,
};
return {
resourceArn: evalFn.functionArn,
policyStatements: [new iam.PolicyStatement({
resources: [evalFn.functionArn],
actions: ['lambda:InvokeFunction'],
})],
parameters,
Resource: this.evalFn.functionArn,
Parameters: sfn.FieldUtils.renderObject(parameters),
};
}
}
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30 changes: 10 additions & 20 deletions packages/@aws-cdk/aws-stepfunctions-tasks/test/evaluate-expression.test.ts
View file
Expand Up @@ -10,10 +10,8 @@ beforeEach(() => {

test('Eval with Node.js', () => {
// WHEN
const task = new sfn.Task(stack, 'Task', {
task: new tasks.EvaluateExpression({
expression: '$.a + $.b',
}),
const task = new tasks.EvaluateExpression(stack, 'Task', {
expression: '$.a + $.b',
});
new sfn.StateMachine(stack, 'SM', {
definition: task,
Expand All @@ -25,14 +23,11 @@ test('Eval with Node.js', () => {
'Fn::Join': [
'',
[
'{"StartAt":"Task","States":{"Task":{"End":true,"Parameters":{"expression":"$.a + $.b","expressionAttributeValues":{"$.a.$":"$.a","$.b.$":"$.b"}},"Type":"Task","Resource":"',
'{"StartAt":"Task","States":{"Task":{"End":true,"Type":"Task","Resource":"',
{
'Fn::GetAtt': [
'Evala0d2ce44871b4e7487a1f5e63d7c3bdc4DAC06E1',
'Arn',
],
'Fn::GetAtt': ['Evala0d2ce44871b4e7487a1f5e63d7c3bdc4DAC06E1', 'Arn'],
},
'"}}}',
'","Parameters":{"expression":"$.a + $.b","expressionAttributeValues":{"$.a.$":"$.a","$.b.$":"$.b"}}}}}',
],
],
},
Expand All @@ -45,10 +40,8 @@ test('Eval with Node.js', () => {

test('expression does not contain paths', () => {
// WHEN
const task = new sfn.Task(stack, 'Task', {
task: new tasks.EvaluateExpression({
expression: '2 + 2',
}),
const task = new tasks.EvaluateExpression(stack, 'Task', {
expression: '2 + 2',
});
new sfn.StateMachine(stack, 'SM', {
definition: task,
Expand All @@ -59,14 +52,11 @@ test('expression does not contain paths', () => {
'Fn::Join': [
'',
[
'{"StartAt":"Task","States":{"Task":{"End":true,"Parameters":{"expression":"2 + 2",\"expressionAttributeValues\":{}},"Type":"Task","Resource":"',
'{"StartAt":"Task","States":{"Task":{"End":true,"Type":"Task","Resource":"',
{
'Fn::GetAtt': [
'Evala0d2ce44871b4e7487a1f5e63d7c3bdc4DAC06E1',
'Arn',
],
'Fn::GetAtt': ['Evala0d2ce44871b4e7487a1f5e63d7c3bdc4DAC06E1', 'Arn'],
},
'"}}}',
'","Parameters":{"expression":"2 + 2","expressionAttributeValues":{}}}}}',
],
],
},
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20 changes: 10 additions & 10 deletions packages/@aws-cdk/aws-stepfunctions-tasks/test/integ.evaluate-expression.expected.json
View file
Expand Up @@ -142,40 +142,40 @@
"StateMachine2E01A3A5": {
"Type": "AWS::StepFunctions::StateMachine",
"Properties": {
"RoleArn": {
"Fn::GetAtt": [
"StateMachineRoleB840431D",
"Arn"
]
},
"DefinitionString": {
"Fn::Join": [
"",
[
"{\"StartAt\":\"Sum\",\"States\":{\"Sum\":{\"Next\":\"Multiply\",\"Parameters\":{\"expression\":\"$.a + $.b\",\"expressionAttributeValues\":{\"$.a.$\":\"$.a\",\"$.b.$\":\"$.b\"}},\"Type\":\"Task\",\"Resource\":\"",
"{\"StartAt\":\"Sum\",\"States\":{\"Sum\":{\"Next\":\"Multiply\",\"Type\":\"Task\",\"ResultPath\":\"$.c\",\"Resource\":\"",
{
"Fn::GetAtt": [
"Evala0d2ce44871b4e7487a1f5e63d7c3bdc4DAC06E1",
"Arn"
]
},
"\",\"ResultPath\":\"$.c\"},\"Multiply\":{\"Next\":\"Wait\",\"Parameters\":{\"expression\":\"$.c * 2\",\"expressionAttributeValues\":{\"$.c.$\":\"$.c\"}},\"Type\":\"Task\",\"Resource\":\"",
"\",\"Parameters\":{\"expression\":\"$.a + $.b\",\"expressionAttributeValues\":{\"$.a.$\":\"$.a\",\"$.b.$\":\"$.b\"}}},\"Multiply\":{\"Next\":\"Wait\",\"Type\":\"Task\",\"ResultPath\":\"$.d\",\"Resource\":\"",
{
"Fn::GetAtt": [
"Evala0d2ce44871b4e7487a1f5e63d7c3bdc4DAC06E1",
"Arn"
]
},
"\",\"ResultPath\":\"$.d\"},\"Wait\":{\"Type\":\"Wait\",\"SecondsPath\":\"$.d\",\"Next\":\"Now\"},\"Now\":{\"End\":true,\"Parameters\":{\"expression\":\"(new Date()).toUTCString()\",\"expressionAttributeValues\":{}},\"Type\":\"Task\",\"Resource\":\"",
"\",\"Parameters\":{\"expression\":\"$.c * 2\",\"expressionAttributeValues\":{\"$.c.$\":\"$.c\"}}},\"Wait\":{\"Type\":\"Wait\",\"SecondsPath\":\"$.d\",\"Next\":\"Now\"},\"Now\":{\"End\":true,\"Type\":\"Task\",\"ResultPath\":\"$.now\",\"Resource\":\"",
{
"Fn::GetAtt": [
"Evala0d2ce44871b4e7487a1f5e63d7c3bdc4DAC06E1",
"Arn"
]
},
"\",\"ResultPath\":\"$.now\"}}}"
"\",\"Parameters\":{\"expression\":\"(new Date()).toUTCString()\",\"expressionAttributeValues\":{}}}}}"
]
]
},
"RoleArn": {
"Fn::GetAtt": [
"StateMachineRoleB840431D",
"Arn"
]
}
},
"DependsOn": [
Expand Down
26 changes: 11 additions & 15 deletions packages/@aws-cdk/aws-stepfunctions-tasks/test/integ.evaluate-expression.ts
View file
Expand Up @@ -12,33 +12,29 @@ import * as tasks from '../lib';
const app = new cdk.App();
const stack = new cdk.Stack(app, 'aws-stepfunctions-integ');

const sum = new sfn.Task(stack, 'Sum', {
task: new tasks.EvaluateExpression({
expression: '$.a + $.b',
}),
const sum = new tasks.EvaluateExpression(stack, 'Sum', {
expression: '$.a + $.b',
resultPath: '$.c',
});

const multiply = new sfn.Task(stack, 'Multiply', {
task: new tasks.EvaluateExpression({
expression: '$.c * 2',
}),
const multiply = new tasks.EvaluateExpression(stack, 'Multiply', {
expression: '$.c * 2',
resultPath: '$.d',
});

const now = new sfn.Task(stack, 'Now', {
task: new tasks.EvaluateExpression({
expression: '(new Date()).toUTCString()',
}),
const now = new tasks.EvaluateExpression(stack, 'Now', {
expression: '(new Date()).toUTCString()',
resultPath: '$.now',
});

const statemachine = new sfn.StateMachine(stack, 'StateMachine', {
definition: sum
.next(multiply)
.next(new sfn.Wait(stack, 'Wait', {
time: sfn.WaitTime.secondsPath('$.d'),
}))
.next(
new sfn.Wait(stack, 'Wait', {
time: sfn.WaitTime.secondsPath('$.d'),
}),
)
.next(now),
});

Expand Down

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