structs: sort policies to avoid order dependence for caching

nomad/structs/funcs.go

@@ -6,6 +6,7 @@ import (
 	"encoding/binary"
 	"fmt"
 	"math"
+	"sort"
 	"strings"
 
 	multierror "github.com/hashicorp/go-multierror"
@@ -273,6 +274,9 @@ func ACLPolicyListHash(policies []*ACLPolicy) string {
 
 // CompileACLObject compiles a set of ACL policies into an ACL object with a cache
 func CompileACLObject(cache *lru.TwoQueueCache, policies []*ACLPolicy) (*acl.ACL, error) {
+	// Sort the policies to ensure consistent ordering
+	sort.Sort(ACLPolicyList(policies))
+
 	// Determine the cache key
 	cacheKey := ACLPolicyListHash(policies)
 	aclRaw, ok := cache.Get(cacheKey)
@@ -300,3 +304,18 @@ func CompileACLObject(cache *lru.TwoQueueCache, policies []*ACLPolicy) (*acl.ACL
 	cache.Add(cacheKey, aclObj)
 	return aclObj, nil
 }
+
+// ACLPolicyList is used to sort a set of policies by name
+type ACLPolicyList []*ACLPolicy
+
+func (l ACLPolicyList) Len() int {
+	return len(l)
+}
+
+func (l ACLPolicyList) Swap(i, j int) {
+	l[i], l[j] = l[j], l[i]
+}
+
+func (l ACLPolicyList) Less(i, j int) bool {
+	return l[i].Name < l[j].Name
+}

nomad/structs/funcs_test.go

@@ -366,4 +366,12 @@ func TestCompileACLObject(t *testing.T) {
 	if aclObj == aclObj3 {
 		t.Fatalf("unexpected same object")
 	}
+
+	// Should be order independent
+	aclObj4, err := CompileACLObject(cache, []*ACLPolicy{p2, p1})
+	assert.Nil(t, err)
+	assert.NotNil(t, aclObj4)
+	if aclObj3 != aclObj4 {
+		t.Fatalf("expected same object")
+	}
 }