update CHANGELOG

CHANGELOG.md

@@ -43,6 +43,7 @@ IMPROVEMENTS:
       without destroying first [GH-2191]
   * provider/aws: Normalize `certificate_chain` in `aws_iam_servier_certificate` to
       prevent unnecessary replacement. [GH-2411]
+  * provider/aws: `aws_instance` supports `monitoring' [GH-2489]
   * provider/aws: `aws_launch_configuration` now supports `enable_monitoring` [GH-2410]
   * provider/aws: Show outputs after `terraform refresh` [GH-2347]
   * provider/docker: `docker_container` has the `privileged`

builtin/providers/aws/resource_aws_instance.go

@@ -471,8 +471,8 @@ func resourceAwsInstanceRead(d *schema.ResourceData, meta interface{}) error {
 	d.Set("ebs_optimized", instance.EBSOptimized)
 
 	if instance.Monitoring != nil && instance.Monitoring.State != nil {
-		monitoring_state := *instance.Monitoring.State
-		d.Set("monitoring", monitoring_state == "enabled" || monitoring_state == "pending")
+		monitoringState := *instance.Monitoring.State
+		d.Set("monitoring", monitoringState == "enabled" || monitoringState == "pending")
 	}
 
 	d.Set("tags", tagsToMap(instance.Tags))

website/source/docs/providers/aws/r/instance.html.markdown

@@ -34,11 +34,11 @@ The following arguments are supported:
 * `placement_group` - (Optional) The Placement Group to start the instance in.
 * `ebs_optimized` - (Optional) If true, the launched EC2 instance will be
      EBS-optimized.
-* `monitoring` - (Optional) If true, the launched EC2 instance will have detailed monitoring enabled.
 * `disable_api_termination` - (Optional) If true, enables [EC2 Instance
      Termination Protection](https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/terminating-instances.html#Using_ChangingDisableAPITermination)
 * `instance_type` - (Required) The type of instance to start
 * `key_name` - (Optional) The key name to use for the instance.
+* `monitoring` - (Optional) If true, the launched EC2 instance will have detailed monitoring enabled. (Available since v0.6.0)
 * `security_groups` - (Optional) A list of security group names to associate with.
    If you are within a non-default VPC, you'll need to use `vpc_security_group_ids` instead.
 * `vpc_security_group_ids` - (Optional) A list of security group IDs to associate with.