can't destroy aws_cloudwatch_log_stream if group has been destroyed

[ahl]

consider this config:

resource "aws_cloudwatch_log_group" "index-logs" {
  name = "/ahl/test"
}

resource "aws_cloudwatch_log_stream" "index-log-stream" {
  name           = "S3Delivery"
  log_group_name = "${aws_cloudwatch_log_group.index-logs.name}"
}

If you delete the log group it will implicitly delete the log stream. A subsequent terraform plan will result in an error:

Refreshing Terraform state in-memory prior to plan...
The refreshed state will be used to calculate this plan, but will not be
persisted to local or remote state storage.

aws_cloudwatch_log_group.index-logs: Refreshing state... (ID: /ahl/test)
aws_cloudwatch_log_stream.index-log-stream: Refreshing state... (ID: S3Delivery)

Error: Error refreshing state: 1 error(s) occurred:

* aws_cloudwatch_log_stream.index-log-stream: 1 error(s) occurred:

* aws_cloudwatch_log_stream.index-log-stream: aws_cloudwatch_log_stream.index-log-stream: ResourceNotFoundException: The specified log group does not exist.
	status code: 400, request id: b4d05427-fab0-11e8-a129-c9ad87f29baf

The problem is that resourceAwsCloudWatchLogStreamRead doesn't properly interpret an error looking up the log stream in the case that the log group doesn't exist.

Output from acceptance testing:

$ make testacc TESTARGS='-run=TestAccAWSCloudWatchLogStream*'
==> Checking that code complies with gofmt requirements...
TF_ACC=1 go test ./... -v -parallel 20 -run=TestAccAWSCloudWatchLogStream* -timeout 120m
?   	github.com/terraform-providers/terraform-provider-aws	[no test files]
=== RUN   TestAccAWSCloudWatchLogStream_basic
=== PAUSE TestAccAWSCloudWatchLogStream_basic
=== RUN   TestAccAWSCloudWatchLogStream_disappears
=== PAUSE TestAccAWSCloudWatchLogStream_disappears
=== RUN   TestAccAWSCloudWatchLogStream_disappears2
=== PAUSE TestAccAWSCloudWatchLogStream_disappears2
=== CONT  TestAccAWSCloudWatchLogStream_basic
=== CONT  TestAccAWSCloudWatchLogStream_disappears2
=== CONT  TestAccAWSCloudWatchLogStream_disappears
--- PASS: TestAccAWSCloudWatchLogStream_disappears2 (8.60s)
--- PASS: TestAccAWSCloudWatchLogStream_disappears (11.38s)
--- PASS: TestAccAWSCloudWatchLogStream_basic (11.52s)
PASS
ok  	github.com/terraform-providers/terraform-provider-aws/aws	11.569s

Added a new test that fails without the fix:

$ make testacc TESTARGS='-run=TestAccAWSCloudWatchLogStream_disappears2'
==> Checking that code complies with gofmt requirements...
TF_ACC=1 go test ./... -v -parallel 20 -run=TestAccAWSCloudWatchLogStream_disappears2 -timeout 120m
?   	github.com/terraform-providers/terraform-provider-aws	[no test files]
=== RUN   TestAccAWSCloudWatchLogStream_disappears2
=== PAUSE TestAccAWSCloudWatchLogStream_disappears2
=== CONT  TestAccAWSCloudWatchLogStream_disappears2
--- FAIL: TestAccAWSCloudWatchLogStream_disappears2 (7.69s)
    testing.go:538: Step 0 error: Error on follow-up refresh: 1 error occurred:
        	* aws_cloudwatch_log_stream.foobar: 1 error occurred:
        	* aws_cloudwatch_log_stream.foobar: aws_cloudwatch_log_stream.foobar: ResourceNotFoundException: The specified log group does not exist.
        	status code: 400, request id: 512d5254-fab1-11e8-9764-fb75fda2d9b2
        
        
        
        
FAIL
FAIL	github.com/terraform-providers/terraform-provider-aws/aws	7.731s
make: *** [testacc] Error 1

[bflad]

Thanks for submitting this, @ahl. It'll be good to get this fixed. 👍 Left some initial comments below -- please let us know if you have any questions or do not have time to implement the feedback.

[bflad]

This new custom function can be replaced with the existing functions from TestAccAWSCloudWatchLogGroup_disappears(), e.g.

var lg cloudwatchlogs.LogGroup
// ...
testAccCheckCloudWatchLogGroupExists("aws_cloudwatch_log_group.foobar", &lg),
testAccCheckCloudWatchLogGroupDisappears(&lg),

[ahl]

I'm less convinced that this is an improvement, but I made the change.

[bflad]

LGTM, thanks @ahl 🚀

--- PASS: TestAccAWSCloudWatchLogStream_disappears_LogGroup (2.96s)
--- PASS: TestAccAWSCloudWatchLogStream_basic (3.95s)
--- PASS: TestAccAWSCloudWatchLogStream_disappears (4.09s)

[bflad]

This has been released in version 1.53.0 of the AWS provider. Please see the Terraform documentation on provider versioning or reach out if you need any assistance upgrading.

[ghost]

I'm going to lock this issue because it has been closed for 30 days ⏳. This helps our maintainers find and focus on the active issues.

If you feel this issue should be reopened, we encourage creating a new issue linking back to this one for added context. Thanks!