The AWS Go SDK automatically provides a default request retryer with exponential backoff that is invoked via setting `MaxRetries` or leaving it `nil` will default to 3. The terraform-aws-provider `config.Client()` sets `MaxRetries` to 0 unless explicitly configured above 0. Previously, we were not overriding this behavior by setting the configuration and therefore not invoking the default request retryer.
The default retryer already handles HTTP error codes above 500, including S3's InternalError response, so the extraneous handling can be removed. This will also start automatically retrying many additional cases, such as temporary networking issues or other retryable AWS service responses.
Changes:
* s3/backend: Add `max_retries` argument
* s3/backend: Enhance S3 NoSuchBucket error to include additional information
This change enables a few related use cases:
* AWS has partitions outside Commercial, GovCloud (US), and China, which are the only endpoints automatically handled by the AWS Go SDK. DynamoDB locking and credential verification can not currently be enabled in those regions.
* Allows usage of any DynamoDB-compatible API for state locking
* Allows usage of any IAM/STS-compatible API for credential verification
Users commonly ask how the S3 backend can be used in an organization that
splits its infrastructure across many AWS accounts.
We've traditionally shied away from making specific recommendations here
because we can't possibly anticipate the different standards and
regulations that constrain each user. This new section attempts to
describe one possible approach that works well with Terraform's workflow,
with the goal that users make adjustments to it taking into account their
unique needs.
Since we are intentionally not being prescriptive here -- instead
considering this just one of many approaches -- it deviates from our usual
active writing style in several places to avoid giving the impression that
these are instructions to be followed exactly, which in some cases
requires the use of passive voice even though that is contrary to our
documentation style guide. For similar reasons, this section is also
light on specific code examples, since we do not wish to encourage users
to just copy-paste the examples without thinking through the consequences.
Brian Flad