Played around with the idea of Lazy value, it seems to help with the case where you have an

Api

and a

StaticSite

, where the frontend needs to know the API endpoint, and the API needs to know the frontend URL. Sample code here https://gist.github.com/fwang/db1e5697913c5533f8b95a4f04464870

Isn't that how the dependencies between stacks work as usual? I know if I print out a value from the CDK code executing locally it says something about

{Token}

in the output before it gets resolved. That only works for a one-way dependency, not a circular one.

I just set one side statically when I encounter this (both sides, in the case you bring up). I do know that doing placeholders in SSM, then filling in later and pulling at runtime is common, though, I just prefer to do nothing at runtime if possible and only use env.

@Adam Fanello yeah it’s part of the Token concept, with LazyValue u can reference the props of a construct which hasn’t been created yet.

My particular annoyance stems from Cognito

AppClients

and using the right one (an autogenerated one that there is no control over) in a

CustomResource

, so it is technically possible it could help, but your point is taken.

SSM was the perfect solution for my problem, as I needed the Site URL at runtime in the Lambda (I was using it in an email that got sent to the user). And now that I have SSM setup I now have a great place for storing secrets

👍 For sure, will be updating the guide @Jay

If it is helpful to anyone, the way I set up my SSM was I created parameters with /all/PARAMETER_NAME for the parameters that were share by all environments, Then I created ones with /STAGE_NAME/PARAMETER_NAME for all parameters specific for a stage. The in my Lambda I wrote a simple utility that loads all the parameters on the first call to get a parameter value using GetParametersByPath first on the all path and then I replace any that are declared in the STAGE_NAME path. That allows me do do things like default the Stripe key to the debug version except in production. :

import boto3
import os

def normalize_name(name):
    """
    Splits a name into its parts.
    """
    parts = name.split('/')
    return parts[-1]

class ParameterStore:
    """
    Class to handle interactions with AWS Parameter Store.
    """
    ssm = boto3.client('ssm')

    @classmethod
    def populate_cache(cls):
        cls.parameter_cache = {}
        response = cls.ssm.get_parameters_by_path(
            Path='/all',
            Recursive=True,
            WithDecryption=True
        )
        for parameter in response['Parameters']:
            cls.parameter_cache[normalize_name(parameter['Name'])] = parameter['Value']

        response = cls.ssm.get_parameters_by_path(
            Path='/' + os.environ['STAGE'],
            Recursive=True,
            WithDecryption=True
        )
        for parameter in response['Parameters']:
            cls.parameter_cache[normalize_name(parameter['Name'])] = parameter['Value']

    @classmethod
    def get(cls, parameter_name):
        if not hasattr(cls, 'parameter_cache'):
            cls.populate_cache()

        return cls.parameter_cache[parameter_name]

@Frank it was also me asking this before, haha.