Environment variable parsing of CDK lambda is not working properly

🐛 Bug Report

What is the problem?

When using environment variables to define lambda function, the value will become totally different in AWS console panel.

Reproduction Steps

1. Define a TIMETABLE variable with 17:00 string.

   const lambdaFn = new lambda.Function(this, 'Singleton', {
     environment: {VALUE: 123, 'TIMETABLE': '17:00'}
   });
   

2. Generate template.yaml.

   cdk synth --no-staging > template.yaml
   

   And the TIMETABLE seems weird from here.

   SingletonXXXXXXX:
     Type: AWS::Lambda::Function
     Environment:
       Variables:
         VALUE: "123"
         TIMETABLE: 17:00
   

3. Go to lambda function of AWS console panel, and the value of environment variable TIMETABLE is 1020.

Environment

• CDK CLI Version: 1.6.1
• Module Version: 1.6.1
• OS: OSX Mojave
• Language: TypeScript

[nija-at]

It’s possible that it was fixed in the underlying YAML package we use - https://github.com/eemeli/yaml/.

Possibly this - https://github.com/eemeli/yaml/commit/884fe078566a3c569e3da1112ff21f45830df2fe ?

[nija-at]

As @rhboyd pointed out, this is coming from the serializing function of the underlying YAML library.

You could use the --json option of cdk synth to generate the output in JSON, or use the one we generate for every synth command that you can find in the cdk.out folder. @tpai - Would this sufficiently mitigate what you’re trying to do here?

cdk deploy uses the JSON format, so this shouldn’t occur when the stack is deployed via the deploy command.