Serverless-application-model: Provisioned Concurrency without DeploymentPreference causes failure on second deployment

[jcts3]

Description:

Using new Provisioned Concurrency capabilities without a DeploymentPreference Property causes a failed update (and consequent failed update rollback) on the second deployment.

I don't think it's an issue with SAM persay - just that it needs to be checked for, and the documentation needs to be updated, i.e. the Release note for v1.18.0 will cause a failed update (and failed rollback) on second deployment. Potentially also add a comment on this table in the bottom 2 rows: https://github.com/awslabs/serverless-application-model/blob/master/versions/2016-10-31.md#properties ?

Steps to reproduce the issue:

1. Deploy a lambda with appropriate ProvisionedConcurrencyConfig property, but without a DeploymentPreference property. This deploys succesfully and works as expected.
2. Make any change to the lambda (e.g. just add a '!' to the hello world message)
3. Build and deploy again.

I reproduced this using this hello world project: https://github.com/jcts3/sam-pc-experiment/blob/master/template.yaml

Observed result:
Function Alias fails to update.
Alias with weights can not be used with Provisioned Concurrency (Service: AWSLambdaInternal; Status Code: 400; Error Code: InvalidParameterValueException; Request ID: 15023437-6d75-40d3-ae4c-313691fcf174)

Invalid function version 1. Function version 1 is already included in routing configuration. (Service: AWSLambdaInternal; Status Code: 400; Error Code: InvalidParameterValueException; Request ID: 92ee7215-037c-417f-8874-0f024bc8022f)

I think what's happening is the alias is trying to shift from version 1to version 2 of the function, but the provisioned concurrency isn't allowing it to do this by itself (i.e. without CodeDeploy managing the change).

Expected result:
Update to not fail. Alias to switch between versions.
OR
First deployment to not succeed due to it missing a required property

Proposed Fix
Update docs to reflect requirement of DeploymentPreference property when using ProvisionedConcurrencyConfig property.
Update pre-deployment checks to prevent deployment without DeploymentPreference when using ProvisionedConcurrencyConfig property.

[praneetap]

@jcts3 thanks for reporting this issue! This is such a helpful issue description. I could reproduce it on my end. I am reaching out to the right people, meanwhile, I agree with you on updating the docs. I don't think we should add a pre-deployment check yet, but let me investigate further and get back to you.

[GrahamMThomas]

I was having this same problem and here is a workaround that worked for me until this is fixed:

      AutoPublishAlias: live
      ProvisionedConcurrencyConfig:
        ProvisionedConcurrentExecutions: 1
      DeploymentPreference:
        Type: AllAtOnce

Should have the same behavior as if the DeploymentPreference wasn't there.

[zd987]

I noticed another issue: ProvisionedConcurrency will not be deployed successfully in below steps:

1. you deploy your lambda function without any version/alias enabled, and also no ProvisionedConcurrencyConfig and DeploymentPreference.
2. in your SAM template introduce "AutoPublishAlias: live", and deploy this SAM
3. introduce ProvisionedConcurrencyConfig together with "DeploymentPreference: Type: AllAtOnce", the ProvisionedConcurrencyConfig is not deployed successfully.

But if you add AutoPublishAlias, ProvisionedConcurrencyConfig, and DeploymentPreference at the same time, it works.

[aaronwht]

Unable to run SAM (v 0.34.0) locally using sam local start-api --port 3030 --skip-pull-image when including the below in template file. Works in production and not locally.

AutoPublishAlias: live
      ProvisionedConcurrencyConfig:
        ProvisionedConcurrentExecutions: 5
      DeploymentPreference:
        Type: AllAtOnce

Error: [InvalidResourceException('Index', 'property ProvisionedConcurrencyConfig not defined for resource of type AWS::Serverless::Function')] ('Index', 'property ProvisionedConcurrencyConfig not defined for resource of type AWS::Serverless::Function')

[praneetap]

Unable to run SAM (v 0.34.0) locally using sam local start-api --port 3030 --skip-pull-image when including the below in template file. Works in production and not locally.

AutoPublishAlias: live
      ProvisionedConcurrencyConfig:
        ProvisionedConcurrentExecutions: 5
      DeploymentPreference:
        Type: AllAtOnce

Error: [InvalidResourceException('Index', 'property ProvisionedConcurrencyConfig not defined for resource of type AWS::Serverless::Function')] ('Index', 'property ProvisionedConcurrencyConfig not defined for resource of type AWS::Serverless::Function')

Can you update your sam-cli to the latest version?