Correct instantiation of AWS session object

[bodgit]

The region needs to be set on the config object before creating the
session so that things like setting AWS_STS_REGIONAL_ENDPOINTS can
take effect.

Also, if credentials cannot be acquired, die at that point instead of
carrying on.

Fixes #420

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[haugenj]

👍 LGTM, thanks!

[bwagner5]

I'm good with your changes, but rather than making users specify: export AWS_STS_REGIONAL_ENDPOINTS regional we can just hard code the config to use regional endpoints. I don't think there's a reason to use the global endpoint w/ NTH. If there's something I'm missing with that assumption, then a second option would be to add the AWS_STS_REGIONAL_ENDPOINTS var in the helm chart's values.yaml and default it to regional.

cfg := aws.NewConfig().
			WithRegion(nthConfig.AWSRegion).
			WithEndpoint(nthConfig.AWSEndpoint).
			WithSTSRegionalEndpoint(endpoints.RegionalSTSEndpoint)
		sess := session.Must(session.NewSessionWithOptions(session.Options{
			Config:            *cfg,
			SharedConfigState: session.SharedConfigEnable,
		}))

[bodgit]

It was purely a case of not changing existing behaviour. You can do exactly as you describe and force the regional endpoint when creating the session object; I've seen some controllers/drivers do that. If you're happy to have that slight change in behaviour then I can tweak the PR. That would be one less Kustomization patch I have to have 😉

[bwagner5]

Cool, I’m good with hard coding it in the session! Mind adding to this pr?

[bodgit]

Done

[bwagner5]

nice! Thank you! LGTM