Ingress controller source key selection support (#703)

Signed-off-by: Steven Kaufer <[email protected]>

Author: kaufers

pkg/controller/ingress/managed.go

@@ -18,6 +18,7 @@ import (
 	"github.com/docker/infrakit/pkg/spi/group"
 	"github.com/docker/infrakit/pkg/spi/instance"
 	"github.com/docker/infrakit/pkg/spi/loadbalancer"
+	"github.com/docker/infrakit/pkg/template"
 	"github.com/docker/infrakit/pkg/types"
 )
 
@@ -71,6 +72,9 @@ type managed struct {
 	groupClientsLock gsync.RWMutex
 
 	lock gsync.RWMutex
+
+	// template that we use to render with a source instance.Description to get the link Key
+	sourceKeySelectorTemplate *template.Template
 }
 
 func (c *managed) state() ingress.Properties {

pkg/controller/ingress/sync.go

@@ -5,6 +5,7 @@ import (
 	"github.com/docker/infrakit/pkg/controller/ingress/types"
 	"github.com/docker/infrakit/pkg/spi/instance"
 	"github.com/docker/infrakit/pkg/spi/loadbalancer"
+	"github.com/docker/infrakit/pkg/template"
 )
 
 func (c *managed) syncRoutesL4() error {
@@ -42,6 +43,23 @@ func (c *managed) syncRoutesL4() error {
 	return nil
 }
 
+func (c *managed) getSourceKeySelectorTemplate() (*template.Template, error) {
+	c.lock.Lock()
+	defer c.lock.Unlock()
+
+	if c.options.SourceKeySelector != "" {
+		if c.sourceKeySelectorTemplate == nil {
+			t, err := types.TemplateFrom([]byte(c.options.SourceKeySelector))
+			if err != nil {
+				return nil, err
+			}
+			c.sourceKeySelectorTemplate = t
+		}
+	}
+
+	return c.sourceKeySelectorTemplate, nil
+}
+
 func (c *managed) syncBackends() error {
 	groupsByVhost, err := c.groups()
 	log.Debug("groups by vhost", "groups", groupsByVhost)
@@ -78,6 +96,7 @@ func (c *managed) syncBackends() error {
 				registered.Add(b)
 			}
 		}
+		log.Info("Registered backends", "backends", registered)
 
 		// all the nodes from all the groups and nodes
 		nodes := mapset.NewSet()
@@ -105,10 +124,25 @@ func (c *managed) syncBackends() error {
 			log.Debug("found backends", "groupID", gid, "desc", desc, "vhost", vhost, "L4", l4.Name())
 
 			for _, inst := range desc.Instances {
-				nodes.Add(inst.ID)
+				t, err := c.getSourceKeySelectorTemplate()
+				if err != nil {
+					return err
+				}
+				if t == nil {
+					nodes.Add(inst.ID)
+				} else {
+					view, err := t.Render(inst)
+					if err != nil {
+						log.Error("cannot index entry", "instance.Description", inst, "err", err)
+						continue
+					}
+					nodes.Add(instance.ID(view))
+				}
 			}
 		}
 
+		log.Info("Group data", "nodes", nodes)
+
 		// compute the difference between registered and nodes
 		toRemove := []instance.ID{}
 		for n := range registered.Difference(nodes).Iter() {

pkg/controller/ingress/types/types.go

@@ -9,6 +9,7 @@ import (
 	"github.com/docker/infrakit/pkg/spi/group"
 	"github.com/docker/infrakit/pkg/spi/instance"
 	"github.com/docker/infrakit/pkg/spi/loadbalancer"
+	"github.com/docker/infrakit/pkg/template"
 	"github.com/docker/infrakit/pkg/types"
 )
 
@@ -112,4 +113,14 @@ type Options struct {
 	// SyncInterval is how often to run the sync. The syntax is the string form
 	// of Go time.Duration (e.g. 1min)
 	SyncInterval types.Duration
+
+	// SourceKeySelector is a string template for selecting the join key from
+	// a source instance.Description.
+	SourceKeySelector string
+}
+
+// TemplateFrom returns a template after it has un-escapes any escape sequences
+func TemplateFrom(source []byte) (*template.Template, error) {
+	buff := template.Unescape(source)
+	return template.NewTemplate("str://"+string(buff), template.Options{MultiPass: false})
 }