middleware/auto: add (#333)

Add auto-load middleware that automatically picks up zones.

Every X seconds it will scan for new zones.
Add tests and documentation.

Make 'make test' use -race.

middleware/file/file.go

@@ -22,8 +22,8 @@ type (
 
 	// Zones maps zone names to a *Zone.
 	Zones struct {
-		Z     map[string]*Zone
-		Names []string
+		Z     map[string]*Zone // A map mapping zone (origin) to the Zone's data
+		Names []string         // All the keys from the map Z as a string slice.
 	}
 )
 
@@ -35,6 +35,7 @@ func (f File) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (i
 		return dns.RcodeServerFailure, errors.New("can only deal with ClassINET")
 	}
 	qname := state.Name()
+	// TODO(miek): match the qname better in the map
 	zone := middleware.Zones(f.Zones.Names).Matches(qname)
 	if zone == "" {
 		if f.Next != nil {
@@ -49,6 +50,8 @@ func (f File) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (i
 	if z == nil {
 		return dns.RcodeServerFailure, nil
 	}
+
+	// This is only for when we are a secondary zones.
 	if r.Opcode == dns.OpcodeNotify {
 		if z.isNotify(state) {
 			m := new(dns.Msg)

middleware/file/reload_test.go

@@ -8,6 +8,7 @@ import (
 	"time"
 
 	"github.com/miekg/coredns/middleware/test"
+
 	"github.com/miekg/dns"
 )
 
@@ -28,7 +29,7 @@ func TestZoneReload(t *testing.T) {
 		t.Fatalf("failed to parse zone: %s", err)
 	}
 
-	z.Reload(nil)
+	z.Reload()
 
 	if _, _, _, res := z.Lookup("miek.nl.", dns.TypeSOA, false); res != Success {
 		t.Fatalf("failed to lookup, got %d", res)

middleware/file/setup.go

@@ -33,7 +33,7 @@ func setup(c *caddy.Controller) error {
 				if len(z.TransferTo) > 0 {
 					z.Notify()
 				}
-				z.Reload(nil)
+				z.Reload()
 			})
 			return nil
 		})
@@ -99,7 +99,7 @@ func fileParse(c *caddy.Controller) (Zones, error) {
 				case "no_reload":
 					noReload = true
 				}
-				// discard from, here, maybe check and show log when we do?
+
 				for _, origin := range origins {
 					if t != nil {
 						z[origin].TransferTo = append(z[origin].TransferTo, t...)
@@ -113,8 +113,6 @@ func fileParse(c *caddy.Controller) (Zones, error) {
 }
 
 // TransferParse parses transfer statements: 'transfer to [address...]'.
-// Exported so secondary can use this as well. For the `file` middleware transfer from does
-// not make sense; make this an error.
 func TransferParse(c *caddy.Controller, secondary bool) (tos, froms []string, err error) {
 	what := c.Val()
 	if !c.NextArg() {

middleware/file/zone.go

@@ -27,9 +27,9 @@ type Zone struct {
 	TransferFrom []string
 	Expired      *bool
 
-	NoReload bool
-	reloadMu sync.RWMutex
-	// TODO: shutdown watcher channel
+	NoReload       bool
+	reloadMu       sync.RWMutex
+	ReloadShutdown chan bool
 }
 
 // Apex contains the apex records of a zone: SOA, NS and their potential signatures.
@@ -42,7 +42,13 @@ type Apex struct {
 
 // NewZone returns a new zone.
 func NewZone(name, file string) *Zone {
-	z := &Zone{origin: dns.Fqdn(name), file: path.Clean(file), Tree: &tree.Tree{}, Expired: new(bool)}
+	z := &Zone{
+		origin:         dns.Fqdn(name),
+		file:           path.Clean(file),
+		Tree:           &tree.Tree{},
+		Expired:        new(bool),
+		ReloadShutdown: make(chan bool),
+	}
 	*z.Expired = false
 	return z
 }
@@ -138,7 +144,7 @@ func (z *Zone) All() []dns.RR {
 }
 
 // Reload reloads a zone when it is changed on disk. If z.NoRoload is true, no reloading will be done.
-func (z *Zone) Reload(shutdown chan bool) error {
+func (z *Zone) Reload() error {
 	if z.NoReload {
 		return nil
 	}
@@ -156,7 +162,7 @@ func (z *Zone) Reload(shutdown chan bool) error {
 		for {
 			select {
 			case event := <-watcher.Events:
-				if path.Clean(event.Name) == z.file {
+				if event.Op == fsnotify.Write && path.Clean(event.Name) == z.file {
 					reader, err := os.Open(z.file)
 					if err != nil {
 						log.Printf("[ERROR] Failed to open `%s' for `%s': %v", z.file, z.origin, err)
@@ -176,7 +182,7 @@ func (z *Zone) Reload(shutdown chan bool) error {
 					log.Printf("[INFO] Successfully reloaded zone `%s'", z.origin)
 					z.Notify()
 				}
-			case <-shutdown:
+			case <-z.ReloadShutdown:
 				watcher.Close()
 				return
 			}