agent/consul: set precedence value on struct itself

agent/consul/intention_endpoint.go

@@ -127,6 +127,9 @@ func (s *Intention) Apply(
 	// Validate. We do not validate on delete since it is valid to only
 	// send an ID in that case.
 	if args.Op != structs.IntentionOpDelete {
+		// Set the precedence
+		args.Intention.UpdatePrecedence()
+
 		if err := args.Intention.Validate(); err != nil {
 			return err
 		}

agent/consul/intention_endpoint_test.go

@@ -67,6 +67,7 @@ func TestIntentionApply_new(t *testing.T) {
 		actual.CreateIndex, actual.ModifyIndex = 0, 0
 		actual.CreatedAt = ixn.Intention.CreatedAt
 		actual.UpdatedAt = ixn.Intention.UpdatedAt
+		ixn.Intention.UpdatePrecedence()
 		assert.Equal(ixn.Intention, actual)
 	}
 }
@@ -201,7 +202,7 @@ func TestIntentionApply_updateGood(t *testing.T) {
 	// Update
 	ixn.Op = structs.IntentionOpUpdate
 	ixn.Intention.ID = reply
-	ixn.Intention.SourceName = "bar"
+	ixn.Intention.SourceName = "*"
 	assert.Nil(msgpackrpc.CallWithCodec(codec, "Intention.Apply", &ixn, &reply))
 
 	// Read
@@ -221,6 +222,7 @@ func TestIntentionApply_updateGood(t *testing.T) {
 		actual.CreateIndex, actual.ModifyIndex = 0, 0
 		actual.CreatedAt = ixn.Intention.CreatedAt
 		actual.UpdatedAt = ixn.Intention.UpdatedAt
+		ixn.Intention.UpdatePrecedence()
 		assert.Equal(ixn.Intention, actual)
 	}
 }
@@ -378,6 +380,7 @@ service "foo" {
 		actual.CreateIndex, actual.ModifyIndex = 0, 0
 		actual.CreatedAt = ixn.Intention.CreatedAt
 		actual.UpdatedAt = ixn.Intention.UpdatedAt
+		ixn.Intention.UpdatePrecedence()
 		assert.Equal(ixn.Intention, actual)
 	}
 }

agent/structs/intention.go

@@ -61,6 +61,11 @@ type Intention struct {
 	// opaque to Consul but is served in API responses.
 	Meta map[string]string
 
+	// Precedence is the order that the intention will be applied, with
+	// larger numbers being applied first. This is a read-only field, on
+	// any intention update it is updated.
+	Precedence int
+
 	// CreatedAt and UpdatedAt keep track of when this record was created
 	// or modified.
 	CreatedAt, UpdatedAt time.Time `mapstructure:"-"`
@@ -160,6 +165,49 @@ func (x *Intention) Validate() error {
 	return result
 }
 
+// UpdatePrecedence sets the Precedence value based on the fields of this
+// structure.
+func (x *Intention) UpdatePrecedence() {
+	// Max maintains the maximum value that the precedence can be depending
+	// on the number of exact values in the destination.
+	var max int
+	switch x.countExact(x.DestinationNS, x.DestinationName) {
+	case 2:
+		max = 9
+	case 1:
+		max = 6
+	case 0:
+		max = 3
+	default:
+		// This shouldn't be possible, just set it to zero
+		x.Precedence = 0
+		return
+	}
+
+	// Given the maximum, the exact value is determined based on the
+	// number of source exact values.
+	countSrc := x.countExact(x.SourceNS, x.SourceName)
+	x.Precedence = max - (2 - countSrc)
+}
+
+// countExact counts the number of exact values (not wildcards) in
+// the given namespace and name.
+func (x *Intention) countExact(ns, n string) int {
+	// If NS is wildcard, it must be zero since wildcards only follow exact
+	if ns == IntentionWildcard {
+		return 0
+	}
+
+	// Same reasoning as above, a wildcard can only follow an exact value
+	// and an exact value cannot follow a wildcard, so if name is a wildcard
+	// we must have exactly one.
+	if n == IntentionWildcard {
+		return 1
+	}
+
+	return 2
+}
+
 // GetACLPrefix returns the prefix to look up the ACL policy for this
 // intention, and a boolean noting whether the prefix is valid to check
 // or not. You must check the ok value before using the prefix.
@@ -354,20 +402,8 @@ func (s IntentionPrecedenceSorter) Swap(i, j int) {
 
 func (s IntentionPrecedenceSorter) Less(i, j int) bool {
 	a, b := s[i], s[j]
-
-	// First test the # of exact values in destination, since precedence
-	// is destination-oriented.
-	aExact := s.countExact(a.DestinationNS, a.DestinationName)
-	bExact := s.countExact(b.DestinationNS, b.DestinationName)
-	if aExact != bExact {
-		return aExact > bExact
-	}
-
-	// Next test the # of exact values in source
-	aExact = s.countExact(a.SourceNS, a.SourceName)
-	bExact = s.countExact(b.SourceNS, b.SourceName)
-	if aExact != bExact {
-		return aExact > bExact
+	if a.Precedence != b.Precedence {
+		return a.Precedence > b.Precedence
 	}
 
 	// Tie break on lexicographic order of the 4-tuple in canonical form (SrcNS,
@@ -387,21 +423,3 @@ func (s IntentionPrecedenceSorter) Less(i, j int) bool {
 	}
 	return a.DestinationName < b.DestinationName
 }
-
-// countExact counts the number of exact values (not wildcards) in
-// the given namespace and name.
-func (s IntentionPrecedenceSorter) countExact(ns, n string) int {
-	// If NS is wildcard, it must be zero since wildcards only follow exact
-	if ns == IntentionWildcard {
-		return 0
-	}
-
-	// Same reasoning as above, a wildcard can only follow an exact value
-	// and an exact value cannot follow a wildcard, so if name is a wildcard
-	// we must have exactly one.
-	if n == IntentionWildcard {
-		return 1
-	}
-
-	return 2
-}

agent/structs/intention_test.go

@@ -232,6 +232,11 @@ func TestIntentionPrecedenceSorter(t *testing.T) {
 				})
 			}
 
+			// Set all the precedence values
+			for _, ixn := range input {
+				ixn.UpdatePrecedence()
+			}
+
 			// Sort
 			sort.Sort(IntentionPrecedenceSorter(input))