Fixes #2990 and #2518. Avoid AttributeError when awscli is invoked fr…

[emurphy]

…om python3 daemon.

[JordonPhillips]

I don't think simply making it None would be the best way to handle this. Any time we try to access it we would end up rasing an error like 'NoneType' object has no attribute 'write' which isn't very helpful. I would prefer we add in a function get_binary_stdin with raises an exception with a descriptive method if stdin isn't available. That would delay the exception while also providing a helpful error message.

[emurphy]

Making the binary_stdin variable None is consistent with sys.stdin being None and is far better than triggering an error. You are welcome to implement your preferred get_binary_stdin function. In the meantime, please merge #2991 so that the aws-cli works for this use case.

[JordonPhillips]

A NoneType exception is not a good experience for a user of a cli tool. The fact that sys.stdin itself will be None just means that we should also do something like this for normal stdin.

[emurphy]

There may be a misunderstanding here. First, one thing to clarify is that I represent a customer of AWS. Our company pays hundreds of thousands of dollars for the privilege to use your services. It is my understanding that you are a paid employee or contractor of AWS.

Like other paying customers, we have encountered an error in the aws-cli software. We have helpfully, at our own expense, provided you with a minimal, no-risk solution. Let us analyze the line of code to ensure there is no misunderstanding there…

Before merging this PR:

binary_stdin = sys.stdin.buffer

After merging this PR:

binary_stdin = sys.stdin.buffer if sys.stdin is not None else None

This is simple, a trivial fix.
Two input conditions are worth considering:

1. sys.stdin is None
2. sys.stdin is not None

In case 1:
In the Before case the program errors. aws-cli breaks, fails to meet a minimum requirement.
In the After case the program continues, with the variable binary_stdin set to None. Not a problem, meets the minimum need.

In case 2, both Before and After have the same result. binary_stdin is safely set to sys.stdin.buffer. All is well.

I could challenge your statement that this fix is not “the best”, but I believe it is irrelevant. In the before case the software breaks; we are not getting from you what we pay for. In the after case your software works, we get what we pay for.

There are no drawbacks; there are no excuses for your inaction.
Please, merge it now.

I will not comment further. I will not change this PR. Our next step, if this issue is not addressed, will be to mention it to our AWS account manager and open a business support case.

Please, as your humble customer, I beg you… merge it now.