Passing CodeUri as a parameter to an application

[jdtjenkins]

Hello,

My team has recently started trying to use SAM, specifically with Applications but we've hit a problem and I can't find anyone else talk about it anywhere else. There are a few issues with passing a CodeUri to a function as a !Ref, which is ok - however our issue is slightly different.

We are wondering if it's possible to pass a local CodeUri (hello-world/) as a parameter into a local application, which then uses that parameter inside a lambda created in that application?

We have tried so far to do exactly that, however when we run sam package, the CodeUri does not get updated to a valid S3 uri as it does with a function outside an application.

So basically running sam package will make the CodeUri inside the generated application template become CodeUri instead of the local path we passed in.

Is there any way to achieve this dynamic application lambda code idea without having to zip and upload our functions before running sam package ?

The code below shows what we are currently trying to do:

template.yaml

AWSTemplateFormatVersion: '2010-09-09'
Transform: AWS::Serverless-2016-10-31
Description: >
  sam-app
  Sample SAM Template for sam-app

Globals:
     Function:
          Timeout: 3
Resources:
     hello-world:
          Type: AWS::Serverless::Application
          Properties:
               Location: ./application.yaml
               Parameters:
                    CodeUri: hello-world/

application.yaml

AWSTemplateFormatVersion: '2010-09-09'
Transform: AWS::Serverless-2016-10-31
Description: >
     RC-sam-app
     RC base SAM App
Globals:
     Function:
          Timeout: 3
Parameters:
     EventName:
          Type: String
          Default: DefaultEvent
     Handler:
          Type: String
          Default: app.lambdaHandler
     CodeUri:
          Type: String
     BatchSize:
          Type: Number
          Default: 1
Resources:
     hello-world:
          Type: AWS::Serverless::Function
          Properties:
               CodeUri: !Ref CodeUri
               Handler: !Ref Handler
               Runtime: nodejs8.10
               Role: <rolearn>

packaged.yaml (generated after sam package)

AWSTemplateFormatVersion: '2010-09-09'
Transform: AWS::Serverless-2016-10-31
Description: 'sam-app2
  Sample SAM Template for sam-app
  '
Globals:
  Function:
    Timeout: 3
Resources:
  hello-world:
    Type: AWS::Serverless::Application
    Properties:
      Location: https://s3.amazonaws.com/<locationPath>.template
      Parameters:
        CodeUri: hello-world/

application.template (pushed up to s3)

AWSTemplateFormatVersion: '2010-09-09'
Transform: AWS::Serverless-2016-10-31
Description: 'RC-sam-app

  RC base SAM App

  '
Globals:
  Function:
    Timeout: 3
Parameters:
  EventName:
    Type: String
    Default: DefaultEvent
  Handler:
    Type: String
    Default: app.lambdaHandler
  CodeUri:
    Type: String
  BatchSize:
    Type: Number
    Default: 1
Resources:
  hello-world:
    Type: AWS::Serverless::Function
    Properties:
      CodeUri:
        // So this cost hasn't been zipped and pushed to S3
        Ref: CodeUri
      Handler:
        Ref: Handler
      Runtime: nodejs8.10
      Role: <roleArn>
      Environment:
        Variables:
          eventName:
            Ref: EventName

Thank you

[jaapspiering]

We have tried so far to do exactly that, however when we run sam package, the CodeUri does not get updated to a valid S3 uri as it does with a function outside an application.

So basically running sam package will make the CodeUri inside the generated application template become CodeUri instead of the local path we passed in.

We are experiencing exactly this, our functions are uploaded to s3, but we are thus getting an invalid packaged.yml file. As a workaround, we run a sam build first, and presumably the new template.yaml file it creates in the .aws-sam/build/ directory triggers sam package to do the right thing.

The functions now get CodeUri's pointing to the build directory output so I guess that makes it work.

[jfuss]

SAM CLI does not replace parameters during sam package. Looks like there might be a case for sam build but typically we do not.

So sam build can be used but would typically not recommend doing this kind of thing for local directories and instead provide where the code lives directly within the template. As this is how SAM CLI is designed.