command/intention/finder: package for finding based on src/dst

api/connect_intention.go

@@ -53,17 +53,30 @@ type Intention struct {
 
 // String returns human-friendly output describing ths intention.
 func (i *Intention) String() string {
-	source := i.SourceName
+	return fmt.Sprintf("%s => %s (%s)",
-	if i.SourceNS != "" {
+		i.SourceString(),
-		source = i.SourceNS + "/" + source
+		i.DestinationString(),
+		i.Action)
+}
+
+// SourceString returns the namespace/name format for the source, or
+// just "name" if the namespace is the default namespace.
+func (i *Intention) SourceString() string {
+	return i.partString(i.SourceNS, i.SourceName)
+}
+
+// DestinationString returns the namespace/name format for the source, or
+// just "name" if the namespace is the default namespace.
+func (i *Intention) DestinationString() string {
+	return i.partString(i.DestinationNS, i.DestinationName)
+}
+
+func (i *Intention) partString(ns, n string) string {
+	if ns != "" {
+		n = ns + "/" + n
 	}
 
-	dest := i.DestinationName
+	return n
-	if i.DestinationNS != "" {
-		dest = i.DestinationNS + "/" + dest
-	}
-
-	return fmt.Sprintf("%s => %s (%s)", source, dest, i.Action)
 }
 
 // IntentionAction is the action that the intention represents. This

command/intention/finder/finder.go

@@ -0,0 +1,46 @@
+package finder
+
+import (
+	"sync"
+
+	"github.com/hashicorp/consul/api"
+)
+
+// Finder finds intentions by a src/dst exact match. There is currently
+// no direct API to do this so this struct downloads all intentions and
+// caches them once, and searches in-memory for this. For now this works since
+// even with a very large number of intentions, the size of the data gzipped
+// over HTTP will be relatively small.
+type Finder struct {
+	// Client is the API client to use for any requests.
+	Client *api.Client
+
+	lock sync.Mutex
+	ixns []*api.Intention // cached list of intentions
+}
+
+// Find finds the intention that matches the given src and dst. This will
+// return nil when the result is not found.
+func (f *Finder) Find(src, dst string) (*api.Intention, error) {
+	f.lock.Lock()
+	defer f.lock.Unlock()
+
+	// If the list of ixns is nil, then we haven't fetched yet, so fetch
+	if f.ixns == nil {
+		ixns, _, err := f.Client.Connect().Intentions(nil)
+		if err != nil {
+			return nil, err
+		}
+
+		f.ixns = ixns
+	}
+
+	// Go through the intentions and find an exact match
+	for _, ixn := range f.ixns {
+		if ixn.SourceString() == src && ixn.DestinationString() == dst {
+			return ixn, nil
+		}
+	}
+
+	return nil, nil
+}

command/intention/finder/finder_test.go

@@ -0,0 +1,49 @@
+package finder
+
+import (
+	"testing"
+
+	"github.com/hashicorp/consul/agent"
+	"github.com/hashicorp/consul/api"
+	"github.com/stretchr/testify/require"
+)
+
+func TestFinder(t *testing.T) {
+	t.Parallel()
+
+	require := require.New(t)
+	a := agent.NewTestAgent(t.Name(), ``)
+	defer a.Shutdown()
+	client := a.Client()
+
+	// Create a set of intentions
+	var ids []string
+	{
+		insert := [][]string{
+			[]string{"a", "b", "c", "d"},
+		}
+
+		for _, v := range insert {
+			ixn := &api.Intention{
+				SourceNS:        v[0],
+				SourceName:      v[1],
+				DestinationNS:   v[2],
+				DestinationName: v[3],
+				Action:          api.IntentionActionAllow,
+			}
+
+			id, _, err := client.Connect().IntentionCreate(ixn, nil)
+			require.NoError(err)
+			ids = append(ids, id)
+		}
+	}
+
+	finder := &Finder{Client: client}
+	ixn, err := finder.Find("a/b", "c/d")
+	require.NoError(err)
+	require.Equal(ids[0], ixn.ID)
+
+	ixn, err = finder.Find("a/c", "c/d")
+	require.NoError(err)
+	require.Nil(ixn)
+}