provider/aws: fix crash when Aurora instance disappears

Usage of a helper function was assuming that an error would be returned
in a not found condition, when in fact a nil pointer was
returned.

Attached test crashes w/o fix, passes with it.

Fixes #5350
Refs #5418

builtin/providers/aws/resource_aws_db_instance.go

@@ -899,6 +899,10 @@ func resourceAwsDbInstanceUpdate(d *schema.ResourceData, meta interface{}) error
  return resourceAwsDbInstanceRead(d, meta)
 }
 
+// resourceAwsDbInstanceRetrieve fetches DBInstance information from the AWS
+// API. It returns an error if there is a communication problem or unexpected
+// error with AWS. When the DBInstance is not found, it returns no error and a
+// nil pointer.
 func resourceAwsDbInstanceRetrieve(
  d *schema.ResourceData, meta interface{}) (*rds.DBInstance, error) {
  conn := meta.(*AWSClient).rdsconn

builtin/providers/aws/resource_aws_rds_cluster_instance.go

@@ -123,8 +123,13 @@ func resourceAwsRDSClusterInstanceCreate(d *schema.ResourceData, meta interface{
 
 func resourceAwsRDSClusterInstanceRead(d *schema.ResourceData, meta interface{}) error {
  db, err := resourceAwsDbInstanceRetrieve(d, meta)
+ // Errors from this helper are always reportable
  if err != nil {
- log.Printf("[WARN] Error on retrieving RDS Cluster Instance (%s): %s", d.Id(), err)
+ return fmt.Errorf("[WARN] Error on retrieving RDS Cluster Instance (%s): %s", d.Id(), err)
+ }
+ // A nil response means "not found"
+ if db == nil {
+ log.Printf("[WARN] RDS Cluster Instance (%s): not found, removing from state.", d.Id())
  d.SetId("")
  return nil
  }

builtin/providers/aws/resource_aws_rds_cluster_instance_test.go

@@ -4,6 +4,7 @@ import (
  "fmt"
  "strings"
  "testing"
+ "time"
 
  "github.com/hashicorp/terraform/helper/acctest"
  "github.com/hashicorp/terraform/helper/resource"
@@ -33,6 +34,28 @@ func TestAccAWSRDSClusterInstance_basic(t *testing.T) {
  })
 }
 
+// https://github.com/hashicorp/terraform/issues/5350
+func TestAccAWSRDSClusterInstance_disappears(t *testing.T) {
+ var v rds.DBInstance
+
+ resource.Test(t, resource.TestCase{
+ PreCheck: func() { testAccPreCheck(t) },
+ Providers: testAccProviders,
+ CheckDestroy: testAccCheckAWSClusterDestroy,
+ Steps: []resource.TestStep{
+ resource.TestStep{
+ Config: testAccAWSClusterInstanceConfig,
+ Check: resource.ComposeTestCheckFunc(
+ testAccCheckAWSClusterInstanceExists("aws_rds_cluster_instance.cluster_instances", &v),
+ testAccAWSClusterInstanceDisappears(&v),
+ ),
+ // A non-empty plan is what we want. A crash is what we don't want. :)
+ ExpectNonEmptyPlan: true,
+ },
+ },
+ })
+}
+
 func testAccCheckAWSClusterInstanceDestroy(s *terraform.State) error {
  for _, rs := range s.RootModule().Resources {
  if rs.Type != "aws_rds_cluster" {
@@ -83,6 +106,34 @@ func testAccCheckAWSDBClusterInstanceAttributes(v *rds.DBInstance) resource.Test
  }
 }
 
+func testAccAWSClusterInstanceDisappears(v *rds.DBInstance) resource.TestCheckFunc {
+ return func(s *terraform.State) error {
+ conn := testAccProvider.Meta().(*AWSClient).rdsconn
+ opts := &rds.DeleteDBInstanceInput{
+ DBInstanceIdentifier: v.DBInstanceIdentifier,
+ }
+ if _, err := conn.DeleteDBInstance(opts); err != nil {
+ return err
+ }
+ return resource.Retry(40*time.Minute, func() *resource.RetryError {
+ opts := &rds.DescribeDBInstancesInput{
+ DBInstanceIdentifier: v.DBInstanceIdentifier,
+ }
+ _, err := conn.DescribeDBInstances(opts)
+ if err != nil {
+ dbinstanceerr, ok := err.(awserr.Error)
+ if ok && dbinstanceerr.Code() == "DBInstanceNotFound" {
+ return nil
+ }
+ return resource.NonRetryableError(
+ fmt.Errorf("Error retrieving DB Instances: %s", err))
+ }
+ return resource.RetryableError(fmt.Errorf(
+ "Waiting for instance to be deleted: %v", v.DBInstanceIdentifier))
+ })
+ }
+}
+
 func testAccCheckAWSClusterInstanceExists(n string, v *rds.DBInstance) resource.TestCheckFunc {
  return func(s *terraform.State) error {
  rs, ok := s.RootModule().Resources[n]