Maximum amount of ELBs is assumed to be 20

[raphtheb]

Unless i'm missing something, it appears that this SDK always assume that the maximum amount of ELBs within an AWS account is 20. It breaks if you request to have more than 20, with this error message:

failed to satisfy constraint: Member must have length less than or equal to 20\n\tstatus code: 400

I believe i've tracked the issue down to models/apis/elasticloadbalancing/2012-06-01/api-2.json
where the assumption of "max":20 is hardcoded (line 1787 as of typing this).

Wouldn't the expected behaviour be to query the API first for the maximal amount of available ELBs, and then using that number as the "max" value?

Trying to look into this, i appear to have stumbled upon another related issue: Is there no AWS API endpoint that returns the current ELB limit? I have not been able to find one. I have, however, found other projects that also hardcode 20 as the limit: https://github.com/jantman/awslimitchecker/blob/master/awslimitchecker/services/elb.py

If that's the case, i suppose this public API modification would be necessary in order to fix this SDK.

Cheers!

[xibz]

Hello @raphtheb thank you for reaching out to us. The SDK does not do validation on max. That error is being returned from the service, ELB. In addition, there is no current way to get the current max amount from the ELB service. Why are you looking to do this? Here is the ELB forums. Others may have had the same concerns and ELB will be able to give a response, while making them aware of the demand for this operation! If you have any more questions, please let us know.

[raphtheb]

So i've contacted our account rep internally to see if there was a way to indeed perform the validation. As it turns out, there is a way. Using https://docs.aws.amazon.com/cli/latest/reference/support/describe-trusted-advisor-check-result.html
and the check-id "eW7HH0l7J9", plus a good deal of parsing, one can get the current limit.

So it is possible to do, i'll see if i have the need to, and time to, work on a PR that would add that functionality.

Thanks for answering, @xibz . We do have a need for more than 20 ELBs within one account here, and keep getting some very strange errors from many places once we break 20.

[xibz]

@raphtheb, awesome news! I wonder if it is natural text that you have to parse. I imagine that if the service ever changes it, it could fail pretty badly. I do not know if that'd be a good place for it in the SDK, but maybe a wrapper in your service may be a better place. Perhaps @jasdel has a different opinion on whether that it would make sense to have in the SDK.
The reason why you are getting strange errors is because ELB, the service, has default max set to 20. You may have to change that limit by submitting a limit increase. That way you don't get those errors from the service.

[raphtheb]

Oh we already had that limit increased to 50 a week ago. That part was the easiest!

[xibz]

@raphtheb - Really? Interesting. That sounds like a bug on the service's end! I now understand your confusion! Do you have any information on the request that failed? Such as region and requestId

[raphtheb]

Region is us-west-2 for everything. The requestId i don't have handy, but will provide as soon as i can.

[xibz]

Hello @raphtheb - I have gotten some feedback from the service and they'd like to know what API calls are you making that is producing this error?

[raphtheb]

Hey @xibz ! We actually found what was the issue internally. Pasting what a coworker sent me with regards to this issue:

The problem actually laid in the 'DescribeTags' call instead of the 'DescribeLoadBalancers' call, from first glance.

Turns out that the API call: elb.DescribeTags(...) only allows for 20 loadbalancers worth of tags to be queried at once. This limitation is not described anywhere in the AWS SDK documentation, nor the source code.

http://docs.aws.amazon.com/sdk-for-go/api/service/elb/#example_ELB_DescribeTags

After being puzzled for the longest time, found myself on the API doc itself for the ELB service and it was actually documented there instead: http://docs.aws.amazon.com/ElasticLoadBalancing/latest/APIReference/API_DescribeTags.html

So we've resolved the issue, it doesn't appear to be in any way, shape or form related to this very project! Thanks a lot for assisting though, it is greatly appreciated.

[xibz]

That is great work on your side @raphtheb! Thank you for your patience! In addition, if you have any additional questions, please reach out to us!