Add imports and exports functionality (Cross-Stack-References) by pmuens · Pull Request #3475 · serverless/serverless

pmuens · 2017-04-14T12:43:19Z

What did you implement:

This WIP PR implements the imports and exports support as described in #3442.

How did you implement it:

Imports

Import values can be defined with the help of the imports keyword.

Those values are then translated into Serverless variables and can therefore be placed anywhere in the serverless.yml file.

The AwsCompileImports plugin checks for the populated variable in the serverless.yml file and replaces this value with the corresponding CloudFormation Fn::ImportValue statement. It's furthermore checked if the Serverless imports variable is imported beforehand so that a population is not happening if it's not explicitly imported.

Exports

Export values can be specified with the help of the exports config variable in the serverless.yml file

Those values are then compiled into corresponding CloudFormation Outputs by the AwsCompileExports plugin.

How can we verify it:

Here's a serverless.yml file which shows how this looks like:

service: service

provider:
  name: aws
  runtime: nodejs6.10

exports:
  writeKey: QWERTY1234

imports:
  users-dev: # the stack which exports this values
    - bucketName # the value which should be imported from that stack

functions:
  hello:
    handler: handler.hello

resources:
  Resources:
    Type: "AWS::S3::Bucket"
    Properties:
      BucketName: ${imports:users-dev.bucketName}

Just run serverless package and take a look in the generated CloudFormation output.

Todos:

Is this ready for review?: NO
Is it a breaking change?: NO

eahefnawy · 2017-04-18T12:44:57Z

    this.envRefSyntax = RegExp(/^env:/g);
    this.optRefSyntax = RegExp(/^opt:/g);
    this.selfRefSyntax = RegExp(/^self:/g);
+    this.importsRefSyntax = RegExp(/^imports:/g);


This source is not needed imo. Adds lots of technical debts. Lets just use "self"

Unfortunately this is not possible (tried it yesterday).

The idea with this PR is that you define imports in your serverless.yml file. Those imports are then translated to Fn::ImportValue statements for AWS which are basically attached to the imports statement in the variable system.

The extension in the variable system only checks if the value is implicitly defined in the imports section so that users can't simply use the imports from the variable system if they are not defined in the service.imports configuration.

Using self here won't help since we're not populating anything.

eahefnawy · 2017-04-18T12:45:19Z

    return valueToPopulate;
  }

+  getValueFromImports(variableString) {


We won't need this method at all

This method checks if the user who want's to use imports via the variable system has explicitly defined what he want's to use in the service.imports config.

eahefnawy · 2017-04-18T13:10:55Z

+
+  compileImports() {
+    const that = this; // save this because of the upcoming scope switch
+    traverse(this.serverless.service).forEach(function (propertyParam) {


why do we use traverse here instead of following the same style we're using with exports?

-> exports = this.serverless.service.exports?

We traverse here since the usage for an import (via the variable system) can be everywhere in the serverless.yml file.

You can see an example in the service I posted for the verification (#3475 (comment)).

gotcha. If we're gonna use the built in variable system via self we won't need that I think

Sounds good!

eahefnawy · 2017-04-18T13:17:16Z

+      if (typeof propertyParam === 'string' && propertyParam.match(/imports:.+/)) {
+        const removedPrefix = propertyParam.split(':')[1];
+        const parts = removedPrefix.split('.');
+        const stack = parts[0];


Not sure if this would work. Remember that the stack name is not just the service name, but it also includes the stage. This pegs the question whether the user should reference a service (in which case he'd have to choose a stage) or the full stack name.

This is the part the user defines in the imports config section.

So he needs to explicitly append the stage to the stack name:

imports: my-service-dev: - foo - bar

ah ok so he provides the stack name not service name. Gotcha! 👍

Yep, exactly! 👍

This way it's possible to e.g. from different stages. Don't know if that's a commonly used feature though...

eahefnawy

I know this is WIP, but just added some comments that might be helpful. 😊

Thanks for jumping into this @pmuens 👍

eahefnawy · 2017-05-09T12:23:14Z

We're now implementing this feature in PR #3575

Closing...

pmuens added the stage/in-progress label Apr 14, 2017

pmuens added this to the 1.12 milestone Apr 14, 2017

pmuens force-pushed the add-imports-and-exports-functionality branch 3 times, most recently from 7c40fed to d215865 Compare April 17, 2017 08:48

First pass on imports functionality

a4f9c91

pmuens force-pushed the add-imports-and-exports-functionality branch from d215865 to a4f9c91 Compare April 17, 2017 08:48

First pass on exports functionality

0038c43

pmuens mentioned this pull request Apr 17, 2017

Support for cross service references via Import and Export #3442

Closed

eahefnawy reviewed Apr 18, 2017

View reviewed changes

eahefnawy requested changes Apr 18, 2017

View reviewed changes

This was referenced Apr 18, 2017

WIP: Add high resource count support #3441

Closed

serverless remove does not show error if stack is not removed due to exported and used CF outputs #2984

Closed

Introduce solution for services with a high resource count #3411

Closed

pmuens modified the milestones: 1.12, 1.13 Apr 25, 2017

eahefnawy closed this May 9, 2017

pmuens deleted the add-imports-and-exports-functionality branch May 9, 2017 12:47

AndreasAugustin mentioned this pull request Feb 25, 2018

Fn::ImportValue for authorizer arn. #4771

Closed

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pmuens commented Apr 14, 2017 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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pmuens Apr 18, 2017 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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pmuens Apr 19, 2017 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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eahefnawy commented May 9, 2017

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pmuens commented Apr 14, 2017 •

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