provider/aws: Fix importing of EIP by IP address (#8970)

* provider/aws: Fix importing of EIP by IP address

EIPs are meant to be imported by their allocation id, however, importing
by their EIP *appears* to work because this API actually accepts IP
lookup, despite the documentation asking for the allocation id.

This PR does:

- update docs on how to import EIPs
- fix case if user imported by IP, to switch to using the alloc id for
the resource id

I chose not to document that looking up by IP is a method of import,
because the AWS  API docs do not explicitly say that looking up by IP is
OK, so I'd rather people not do it if it's not documented to stay that
way.

Alternatively, we could parse the resource ID and reject it (remove from
state with error/warning) if it doesn't match the `eipalloc-*` format,
but I thought this was a bit better UX.

* fix issue with swapping IDs on EC2 Classic

* update docs

* update comment

builtin/providers/aws/resource_aws_eip.go

@@ -3,6 +3,7 @@ package aws
 import (
 	"fmt"
 	"log"
+	"net"
 	"strings"
 	"time"
 
@@ -127,12 +128,12 @@ func resourceAwsEipRead(d *schema.ResourceData, meta interface{}) error {
 	}
 
 	log.Printf(
-		"[DEBUG] EIP describe configuration: %#v (domain: %s)",
+		"[DEBUG] EIP describe configuration: %s (domain: %s)",
 		req, domain)
 
 	describeAddresses, err := ec2conn.DescribeAddresses(req)
 	if err != nil {
-		if ec2err, ok := err.(awserr.Error); ok && ec2err.Code() == "InvalidAllocationID.NotFound" {
+		if ec2err, ok := err.(awserr.Error); ok && (ec2err.Code() == "InvalidAllocationID.NotFound" || ec2err.Code() == "InvalidAddress.NotFound") {
 			d.SetId("")
 			return nil
 		}
@@ -173,6 +174,13 @@ func resourceAwsEipRead(d *schema.ResourceData, meta interface{}) error {
 
 	d.Set("domain", address.Domain)
 
+	// Force ID to be an Allocation ID if we're on a VPC
+	// This allows users to import the EIP based on the IP if they are in a VPC
+	if *address.Domain == "vpc" && net.ParseIP(id) != nil {
+		log.Printf("[DEBUG] Re-assigning EIP ID (%s) to it's Allocation ID (%s)", d.Id(), *address.AllocationId)
+		d.SetId(*address.AllocationId)
+	}
+
 	return nil
 }
 

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

@@ -107,4 +107,19 @@ The following attributes are exported:
 * `instance` - Contains the ID of the attached instance.
 * `network_interface` - Contains the ID of the attached network interface.
 
+
+## Import
+
+EIPs in a VPC can be imported using their Allocation ID, e.g.
+
+```
+$ terraform import aws_eip.bar eipalloc-00a10e96
+```
+
+EIPs in EC2 Classic can be imported using their Public IP, e.g.
+
+```
+$ terraform import aws_eip.bar 52.0.0.0
+```
+
 [1]: https://docs.aws.amazon.com/fr_fr/AWSEC2/latest/APIReference/API_AssociateAddress.html