Configurable zone reload interval in file plugin (#2110)

* Configurable zone reload interval in file plugin

* passing reload config from auto plugin to file plugin. removed noReload property from Zone struct. fixed tests based on short file reload hack

plugin/auto/README.md

@@ -16,6 +16,7 @@ zonefile. New or changed zones are automatically picked up from disk.
 ~~~
 auto [ZONES...] {
     directory DIR [REGEXP ORIGIN_TEMPLATE [TIMEOUT]]
+    reload DURATION
     no_reload
     upstream [ADDRESS...]
 }
@@ -31,8 +32,10 @@ are used.
   name `db.example.com`, the extracted origin will be `example.com`. **TIMEOUT** specifies how often
   CoreDNS should scan the directory; the default is every 60 seconds. This value is in seconds.
   The minimum value is 1 second.
-* `no_reload` by default CoreDNS will try to reload a zone every minute and reloads if the
-  SOA's serial has changed. This option disables that behavior.
+* `reload` interval to perform reload of zone if SOA version changes. Default is one minute. 
+  Value of `0` means to not scan for changes and reload. eg. `30s` checks zonefile every 30 seconds 
+  and reloads zone when serial changes.
+* `no_reload` deprecated. Sets reload to 0.
 * `upstream` defines upstream resolvers to be used resolve external names found (think CNAMEs)
   pointing to external names. **ADDRESS** can be an IP address, an IP:port or a string pointing to
   a file that is structured as /etc/resolv.conf. If no **ADDRESS** is given, CoreDNS will resolve CNAMEs

plugin/auto/auto.go

@@ -32,7 +32,7 @@ type (
 
 		// In the future this should be something like ZoneMeta that contains all this stuff.
 		transferTo []string
-		noReload   bool
+		ReloadInterval time.Duration
 		upstream   upstream.Upstream // Upstream for looking up names during the resolution process.
 
 		duration time.Duration

plugin/auto/setup.go

@@ -144,8 +144,15 @@ func autoParse(c *caddy.Controller) (Auto, error) {
 					a.loader.duration = time.Duration(i) * time.Second
 				}
 
+			case "reload":
+				d, err := time.ParseDuration(c.RemainingArgs()[0])
+				if err != nil {
+					return a, plugin.Error("file", err)
+				}
+				a.loader.ReloadInterval = d
+
 			case "no_reload":
-				a.loader.noReload = true
+				a.loader.ReloadInterval = 0
 
 			case "upstream":
 				args := c.RemainingArgs()

plugin/auto/walk.go

@@ -52,7 +52,7 @@ func (a Auto) Walk() error {
 			return nil
 		}
 
-		zo.NoReload = a.loader.noReload
+		zo.ReloadInterval = a.loader.ReloadInterval
 		zo.Upstream = a.loader.upstream
 		zo.TransferTo = a.loader.transferTo
 

plugin/file/README.md

@@ -27,6 +27,7 @@ If you want to round robin A and AAAA responses look at the *loadbalance* plugin
 ~~~
 file DBFILE [ZONES... ] {
     transfer to ADDRESS...
+    reload DURATION
     no_reload
     upstream [ADDRESS...]
 }
@@ -36,8 +37,10 @@ file DBFILE [ZONES... ] {
   the direction. **ADDRESS** must be denoted in CIDR notation (127.0.0.1/32 etc.) or just as plain
   addresses. The special wildcard `*` means: the entire internet (only valid for 'transfer to').
   When an address is specified a notify message will be send whenever the zone is reloaded.
-* `no_reload` by default CoreDNS will try to reload a zone every minute and reloads if the
-  SOA's serial has changed. This option disables that behavior.
+* `reload` interval to perform reload of zone if SOA version changes. Default is one minute. 
+  Value of `0` means to not scan for changes and reload. eg. `30s` checks zonefile every 30 seconds 
+  and reloads zone when serial changes.
+* `no_reload` deprecated. Sets reload to 0.
 * `upstream` defines upstream resolvers to be used resolve external names found (think CNAMEs)
   pointing to external names. This is only really useful when CoreDNS is configured as a proxy, for
   normal authoritative serving you don't need *or* want to use this. **ADDRESS** can be an IP

plugin/file/lookup.go

@@ -30,11 +30,11 @@ func (z *Zone) Lookup(state request.Request, qname string) ([]dns.RR, []dns.RR,
 	qtype := state.QType()
 	do := state.Do()
 
-	if !z.NoReload {
+	if 0 < z.ReloadInterval {
 		z.reloadMu.RLock()
 	}
 	defer func() {
-		if !z.NoReload {
+		if 0 < z.ReloadInterval {
 			z.reloadMu.RUnlock()
 		}
 	}()

plugin/file/reload.go

@@ -5,15 +5,14 @@ import (
 	"time"
 )
 
-// TickTime is the default time we use to reload zone. Exported to be tweaked in tests.
-var TickTime = 1 * time.Minute
+// TickTime is clock resolution. By default ticks every second. Handler checks if reloadInterval has been reached on every tick.
+var TickTime = 1 * time.Second
 
 // Reload reloads a zone when it is changed on disk. If z.NoRoload is true, no reloading will be done.
 func (z *Zone) Reload() error {
-	if z.NoReload {
+	if z.ReloadInterval == 0 {
 		return nil
 	}
-
 	tick := time.NewTicker(TickTime)
 
 	go func() {
@@ -22,6 +21,13 @@ func (z *Zone) Reload() error {
 			select {
 
 			case <-tick.C:
+				if z.LastReloaded.Add(z.ReloadInterval).After(time.Now()) {
+					//reload interval not reached yet
+					continue
+				}
+				//saving timestamp of last attempted reload
+				z.LastReloaded = time.Now()
+
 				zFile := z.File()
 				reader, err := os.Open(zFile)
 				if err != nil {

plugin/file/reload_test.go

@@ -29,6 +29,7 @@ func TestZoneReload(t *testing.T) {
 	}
 
 	TickTime = 500 * time.Millisecond
+	z.ReloadInterval = 500 * time.Millisecond
 	z.Reload()
 	time.Sleep(time.Second)
 

plugin/file/setup.go

@@ -3,6 +3,7 @@ package file
 import (
 	"os"
 	"path"
+	"time"
 
 	"github.com/coredns/coredns/core/dnsserver"
 	"github.com/coredns/coredns/plugin"
@@ -91,7 +92,7 @@ func fileParse(c *caddy.Controller) (Zones, error) {
 			names = append(names, origins[i])
 		}
 
-		noReload := false
+		reload := 1 * time.Minute
 		upstr := upstream.Upstream{}
 		t := []string{}
 		var e error
@@ -104,8 +105,15 @@ func fileParse(c *caddy.Controller) (Zones, error) {
 					return Zones{}, e
 				}
 
+			case "reload":
+				d, err := time.ParseDuration(c.RemainingArgs()[0])
+				if err != nil {
+					return Zones{}, plugin.Error("file", err)
+				}
+				reload = d
+
 			case "no_reload":
-				noReload = true
+				reload = 0
 
 			case "upstream":
 				args := c.RemainingArgs()
@@ -122,7 +130,7 @@ func fileParse(c *caddy.Controller) (Zones, error) {
 				if t != nil {
 					z[origin].TransferTo = append(z[origin].TransferTo, t...)
 				}
-				z[origin].NoReload = noReload
+				z[origin].ReloadInterval = reload
 				z[origin].Upstream = upstr
 			}
 		}

plugin/file/shutdown.go

@@ -2,7 +2,7 @@ package file
 
 // OnShutdown shuts down any running go-routines for this zone.
 func (z *Zone) OnShutdown() error {
-	if !z.NoReload {
+	if 0 < z.ReloadInterval {
 		z.reloadShutdown <- true
 	}
 	return nil

plugin/file/zone.go

@@ -6,6 +6,7 @@ import (
 	"path"
 	"strings"
 	"sync"
+	"time"
 
 	"github.com/coredns/coredns/plugin/file/tree"
 	"github.com/coredns/coredns/plugin/pkg/upstream"
@@ -27,7 +28,8 @@ type Zone struct {
 	TransferFrom []string
 	Expired      *bool
 
-	NoReload       bool
+	ReloadInterval time.Duration
+	LastReloaded   time.Time
 	reloadMu       sync.RWMutex
 	reloadShutdown chan bool
 	Upstream       upstream.Upstream // Upstream for looking up names during the resolution process
@@ -50,6 +52,7 @@ func NewZone(name, file string) *Zone {
 		Tree:           &tree.Tree{},
 		Expired:        new(bool),
 		reloadShutdown: make(chan bool),
+		LastReloaded:   time.Now(),
 	}
 	*z.Expired = false
 
@@ -161,7 +164,7 @@ func (z *Zone) TransferAllowed(state request.Request) bool {
 // All returns all records from the zone, the first record will be the SOA record,
 // otionally followed by all RRSIG(SOA)s.
 func (z *Zone) All() []dns.RR {
-	if !z.NoReload {
+	if z.ReloadInterval > 0 {
 		z.reloadMu.RLock()
 		defer z.reloadMu.RUnlock()
 	}

test/file_reload_test.go

@@ -24,7 +24,9 @@ func TestZoneReload(t *testing.T) {
 
 	// Corefile with two stanzas
 	corefile := `example.org:0 {
-       file ` + name + `
+       file ` + name + ` {
+           reload 1s
+       }
 }
 
 example.net:0 {