cli: hotswapping Lambda environment variable with tokens results in an error

[tmokmss]

Describe the bug

Hi I found the following issue regarding hotswap. I'll dig into the actual code to find the root cause later.

Expected Behavior

Hotswap successes.

Current Behavior

When hotswapping, the error below happens.

 ❌  SampleStack failed: InvalidParameterType: Expected params.Environment.Variables['someToken'] to be a string
    at ParamValidator.fail (/Users/cdk/sample/node_modules/aws-sdk/lib/param_validator.js:50:37)
    at ParamValidator.validateType (/Users/cdk/sample/node_modules/aws-sdk/lib/param_validator.js:233:10)
    at ParamValidator.validateString (/Users/cdk/sample/node_modules/aws-sdk/lib/param_validator.js:155:32)
    at ParamValidator.validateScalar (/Users/cdk/sample/node_modules/aws-sdk/lib/param_validator.js:131:21)
    at ParamValidator.validateMember (/Users/cdk/sample/node_modules/aws-sdk/lib/param_validator.js:95:21)
    at ParamValidator.validateMap (/Users/cdk/sample/node_modules/aws-sdk/lib/param_validator.js:118:14)
    at ParamValidator.validateMember (/Users/cdk/sample/node_modules/aws-sdk/lib/param_validator.js:93:21)
    at ParamValidator.validateStructure (/Users/cdk/sample/node_modules/aws-sdk/lib/param_validator.js:76:14)
    at ParamValidator.validateMember (/Users/cdk/sample/node_modules/aws-sdk/lib/param_validator.js:89:21)
    at ParamValidator.validateStructure (/Users/cdk/sample/node_modules/aws-sdk/lib/param_validator.js:76:14) {
  code: 'InvalidParameterType',
  time: 2022-09-17T02:35:50.431Z
}

 ❌ Deployment failed: Error: Stack Deployments Failed: InvalidParameterType: Expected params.Environment.Variables['someToken'] to be a string
    at deployStacks (/Users/cdk/sample/node_modules/aws-cdk/lib/deploy.ts:61:11)
    at processTicksAndRejections (node:internal/process/task_queues:96:5)
    at CdkToolkit.deploy (/Users/cdk/sample/node_modules/aws-cdk/lib/cdk-toolkit.ts:312:7)
    at initCommandLine (/Users/cdk/sample/node_modules/aws-cdk/lib/cli.ts:349:12)

Stack Deployments Failed: InvalidParameterType: Expected params.Environment.Variables['someToken'] to be a string

Reproduction Steps

1. Deploy the stack below
2. Change someLiteral: '1' to someLiteral: '2' to trigger a hotswap
3. run cdk deploy --hotswap and you can see the above error.

import * as cdk from 'aws-cdk-lib';
import { Construct } from 'constructs';
import * as lambda from 'aws-cdk-lib/aws-lambda';
import { Role, ServicePrincipal } from 'aws-cdk-lib/aws-iam';

export class SampleStack extends cdk.Stack {
  constructor(scope: Construct, id: string, props?: cdk.StackProps) {
    super(scope, id, props);

    const role = new Role(this, 'Role', {
      assumedBy: new ServicePrincipal('sns.amazonaws.com'),
    });

    new lambda.Function(this, 'Function', {
      code: lambda.Code.fromInline('exports.handler=()=>{}'),
      runtime: lambda.Runtime.NODEJS_16_X,
      handler: 'index.handler',
      environment: {
        someToken: role.roleArn,
        someLiteral: '1',
      },
    });
  }
}

Possible Solution

No response

Additional Information/Context

Lambda environment variable hotswap was introduced in #21532.

CDK CLI Version

2.42.0

Framework Version

2.42.0

Node.js Version

16.13.1

OS

macOS

Language

Typescript

Language Version

No response

Other information

No response

[zxkane]

met the same issue when running cdk deploy --watch,

change the env of lambda reproducing the issue.

The workaround is deploying the changes without --watch option via cdk deploy only.

[github-actions]

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