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