"Region" value usage seems inconsistent across client/web-ui

[nloding]

In the lex-web-ui configuration, there are multiple values for region:

{
  "region": "us-east-2",
  "cognito": {
    "aws_cognito_region": "us-east-2",
    "region": "us-east-2"
  },
  "lex": {
    "region": "us-east-1",
  },

Most of my test resources have long been deployed to us-east-2, but Lex v2 only has endpoints in the us-east-1 region. (In other words, Cognitor is us-east-2, Lex is us-east-1 in my configuration.) If I set the top-level region value to "us-east-1", then the Lex runtime instantiates correctly but Cognito fails because it is looking for us-east-1. If I change the top-level region value to "us-east-2", then the reverse happens: Cognito connects, but Lex throws errors (specifically CORS errors because it's trying to hit a us-east-2 runtime endpoint and getting a 404).

I would have expected the cognito.aws_cognito_region or cognito.region and lex.region values to take precedence and not have all the configurations depend on the top-level region value.

The only fix/workaround I have found is to change this line in LexWeb.vue to hardcode the value as "us-east-1".

[atjohns]

Good catch, I don't think I've ever tried a multi-region deployment before so this has never come up. I will look into it

[bobpskier]

@atjohns @nloding The last I recall, both cognito and lex must be used in the same region. Cognito tokens generated in a different region from where lex service is being called will not be accepted by lex.

[nloding]

@bobpskier I'll be honest, I have no idea exactly how my local setup is working, but I do know that I have Cognito in us-east-2 and Lex in us-east-1 and the web-ui is working locally. I think the region values should be clarified either way: if you need to have all resources in the same region, then I think it makes sense to remove the individual region values in the configuration and samples.