From b8a9261d0516b3f7a2642cfd9951c7050c892d8f Mon Sep 17 00:00:00 2001
From: Adam Mckaig <adam.mckaig@gmail.com>
Date: Tue, 15 Dec 2015 00:01:17 -0500
Subject: [PATCH] Add group by AWS tags

---
 parser_test.go | 12 +++++++++---
 resource.go    | 31 ++++++++++++++++++++++++++++++-
 2 files changed, 39 insertions(+), 4 deletions(-)

diff --git a/parser_test.go b/parser_test.go
index f9b7302..68e8203 100644
--- a/parser_test.go
+++ b/parser_test.go
@@ -26,7 +26,9 @@ const exampleStateFile = `
 						"id": "i-aaaaaaaa",
 						"attributes": {
 							"id": "i-aaaaaaaa",
-							"private_ip": "10.0.0.1"
+							"private_ip": "10.0.0.1",
+							"tags.#": "1",
+							"tags.Role": "Web"
 						}
 					}
 				},
@@ -139,14 +141,18 @@ const expectedListOutput = `
 	"digitalocean_droplet":          ["192.168.0.3"],
 	"cloudstack_instance":           ["10.2.1.5"],
 	"vsphere_virtual_machine":       ["10.20.30.40"],
-	"openstack_compute_instance_v2": ["10.120.0.226"]
+	"openstack_compute_instance_v2": ["10.120.0.226"],
+
+	"role_web": ["10.0.0.1"]
 }
 `
 
 const expectedHostOneOutput = `
 {
 	"id":"i-aaaaaaaa",
-	"private_ip":"10.0.0.1"
+	"private_ip":"10.0.0.1",
+	"tags.#": "1",
+	"tags.Role": "Web"
 }
 `
 
diff --git a/resource.go b/resource.go
index 77c62a1..9086847 100644
--- a/resource.go
+++ b/resource.go
@@ -4,6 +4,7 @@ import (
 	"fmt"
 	"regexp"
 	"strconv"
+	"strings"
 )
 
 // keyNames contains the names of the keys to check for in each resource in the
@@ -81,11 +82,39 @@ func (r Resource) IsSupported() bool {
 // Groups returns the list of Ansible groups which this resource should be
 // included in.
 func (r Resource) Groups() []string {
-	return []string{
+	groups := []string{
 		r.baseName,
 		r.NameWithCounter(),
 		r.resourceType,
 	}
+
+	for k, v := range r.Tags() {
+		g := fmt.Sprintf("%s_%s", k, v)
+		groups = append(groups, g)
+	}
+
+	return groups
+}
+
+// Tags returns a map of arbitrary key/value pairs explicitly associated with
+// the resource. Different providers have different mechanisms for attaching
+// these.
+func (r Resource) Tags() map[string]string {
+	t := map[string]string{}
+
+	switch r.resourceType {
+	case "aws_instance":
+		for k, v := range r.Attributes() {
+			parts := strings.SplitN(k, ".", 2)
+			if len(parts) == 2 && parts[0] == "tags" && parts[1] != "#" {
+				kk := strings.ToLower(parts[1])
+				vv := strings.ToLower(v)
+				t[kk] = vv
+			}
+		}
+	}
+
+	return t
 }
 
 // Attributes returns a map containing everything we know about this resource.