Because `aws_security_group_rule` resources are an abstraction on top of
Security Groups, they must interact with the AWS Security Group APIs in
a pattern that often results in lots of parallel requests interacting
with the same security group.
We've found that this pattern can trigger race conditions resulting in
inconsistent behavior, including:
* Rules that report as created but don't actually exist on AWS's side
* Rules that show up in AWS but don't register as being created
locally, resulting in follow up attempts to authorize the rule
failing w/ Duplicate errors
Here, we introduce a per-SG mutex that must be held by any security
group before it is allowed to interact with AWS APIs. This protects the
space between `DescribeSecurityGroup` and `Authorize*` / `Revoke*`
calls, ensuring that no other rules interact with the SG during that
span.
The included test exposes the race by applying a security group with
lots of rules, which based on the dependency graph can all be handled in
parallel. This fails most of the time without the new locking behavior.
I've omitted the mutex from `Read`, since it is only called during the
Refresh walk when no changes are being made, meaning a bunch of parallel
`DescribeSecurityGroup` API calls should be consistent in that case.
* master: (95 commits)
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upgrade a warning to error
add some logging around create/update requests for IAM user
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Build using `make test` on Travis CI
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provider/aws: Fix error format in Kinesis Firehose
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Changes to Aws Kinesis Firehouse Docs
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modify aws_iam_user_test to correctly check username and path for initial and changed username/path
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Prompt for input variables before context validate
Removing the AWS DBInstance Acceptance Test for withoutEngine as this is now part of the checkInstanceAttributes func
Making engine_version be computed in the db_instance provider
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clint shryock