Sort terraform literals in ELB task

Fixes #3578

upup/pkg/fi/cloudup/awstasks/load_balancer.go

@@ -634,10 +634,12 @@ func (_ *LoadBalancer) RenderTerraform(t *terraform.TerraformTarget, a, e, chang
 	for _, subnet := range e.Subnets {
 		tf.Subnets = append(tf.Subnets, subnet.TerraformLink())
 	}
+	terraform.SortLiterals(tf.Subnets)
 
 	for _, sg := range e.SecurityGroups {
 		tf.SecurityGroups = append(tf.SecurityGroups, sg.TerraformLink())
 	}
+	terraform.SortLiterals(tf.SecurityGroups)
 
 	for loadBalancerPort, listener := range e.Listeners {
 		loadBalancerPortInt, err := strconv.ParseInt(loadBalancerPort, 10, 64)

upup/pkg/fi/cloudup/terraform/literal.go

@@ -19,6 +19,8 @@ package terraform
 import (
 	"encoding/json"
 	"sort"
+
+	"github.com/golang/glog"
 )
 
 type Literal struct {
@@ -63,7 +65,8 @@ func (a byKey) Less(i, j int) bool {
 	return a[i].key < a[j].key
 }
 
-func sortLiterals(v []*Literal, dedup bool) ([]*Literal, error) {
+// buildSortProxies maps a list of Literals to a list of literalWithJSON
+func buildSortProxies(v []*Literal) ([]*literalWithJSON, error) {
 	var proxies []*literalWithJSON
 	for _, l := range v {
 		k, err := json.Marshal(l)
@@ -76,16 +79,39 @@ func sortLiterals(v []*Literal, dedup bool) ([]*Literal, error) {
 		})
 	}
 
+	return proxies, nil
+}
+
+// SortLiterals sorts a list of Literal, by key.  It does so in-place
+func SortLiterals(v []*Literal) {
+	proxies, err := buildSortProxies(v)
+	if err != nil {
+		// Very unexpected
+		glog.Fatalf("error processing terraform Literal: %v", err)
+	}
+
 	sort.Sort(byKey(proxies))
 
-	var sorted []*Literal
+	for i := range proxies {
+		v[i] = proxies[i].literal
+	}
+}
+
+func DedupLiterals(v []*Literal) ([]*Literal, error) {
+	proxies, err := buildSortProxies(v)
+	if err != nil {
+		return nil, err
+	}
+
+	sort.Sort(byKey(proxies))
+
+	var deduped []*Literal
 	for i, p := range proxies {
-		if dedup && i != 0 && proxies[i-1].key == proxies[i].key {
+		if i != 0 && proxies[i-1].key == proxies[i].key {
 			continue
 		}
-
-		sorted = append(sorted, p.literal)
+		deduped = append(deduped, p.literal)
 	}
 
-	return sorted, nil
+	return deduped, nil
 }

upup/pkg/fi/cloudup/terraform/target.go

@@ -204,12 +204,12 @@ func (t *TerraformTarget) Finish(taskMap map[string]fi.Task) error {
 		if v.Value != nil {
 			tfVar["value"] = v.Value
 		} else {
-			dedup := true
-			sorted, err := sortLiterals(v.ValueArray, dedup)
+			SortLiterals(v.ValueArray)
+			deduped, err := DedupLiterals(v.ValueArray)
 			if err != nil {
-				return fmt.Errorf("error sorting literals: %v", err)
+				return err
 			}
-			tfVar["value"] = sorted
+			tfVar["value"] = deduped
 		}
 		outputVariables[tfName] = tfVar
 	}