Sort resource names for consistent output

parser.go

@@ -4,6 +4,7 @@ import (
 	"encoding/json"
 	"io"
 	"io/ioutil"
+	"sort"
 )
 
 type state struct {
@@ -33,12 +34,12 @@ func (s *state) resources() []*Resource {
 	inst := make([]*Resource, 0)
 
 	for _, m := range s.Modules {
-		for k, rs := range m.ResourceStates {
+		for _, k := range m.resourceKeys() {
 
 			// Terraform stores resources in a name->map map, but we need the name to
 			// decide which groups to include the resource in. So wrap it in a higher-
 			// level object with both properties.
-			r, err := NewResource(k, rs)
+			r, err := NewResource(k, m.ResourceStates[k])
 			if err != nil {
 				continue
 			}
@@ -56,6 +57,23 @@ type moduleState struct {
 	ResourceStates map[string]resourceState `json:"resources"`
 }
 
+// resourceKeys returns a sorted slice of the key names of the resources in this
+// module. Do this instead of range over ResourceStates, to ensure that the
+// output is consistent.
+func (ms *moduleState) resourceKeys() []string {
+	lk := len(ms.ResourceStates)
+	keys := make([]string, lk, lk)
+	i := 0
+
+	for k := range ms.ResourceStates {
+		keys[i] = k
+		i += 1
+	}
+
+	sort.Strings(keys)
+	return keys
+}
+
 type resourceState struct {
 
 	// Populated from statefile