Plugin/RELOAD - Tune usage of var global, add limit to options (#1457)

* tune usage of var global, add limit to options

* update readme for minimal values

* useless change to quick-off codecov

* fix msgs for min values and tune the flag for end of reload usage, with a 'maybe' option

* adding UT for min values, adding MD5 of corefile on the log

1 files changed, 22 insertions, 11 deletions

diff --git a/plugin/reload/reload.go b/plugin/reload/reload.go
index e469b4526..e7031455f 100644
--- a/plugin/reload/reload.go
+++ b/plugin/reload/reload.go
@@ -9,12 +9,15 @@ import (
 )
 
 // reload periodically checks if the Corefile has changed, and reloads if so
+const (
+	unused    = 0
+	maybeUsed = 1
+	used      = 2
+)
 
 type reload struct {
-	instance *caddy.Instance
 	interval time.Duration
-	sum      [md5.Size]byte
-	stopped  bool
+	usage    int
 	quit     chan bool
 }
 
@@ -26,13 +29,14 @@ func hook(event caddy.EventName, info interface{}) error {
 	// if reload is removed from the Corefile, then the hook
 	// is still registered but setup is never called again
 	// so we need a flag to tell us not to reload
-	if r.stopped {
+	if r.usage == unused {
 		return nil
 	}
 
 	// this should be an instance. ok to panic if not
-	r.instance = info.(*caddy.Instance)
-	r.sum = md5.Sum(r.instance.Caddyfile().Body())
+	instance := info.(*caddy.Instance)
+	md5sum := md5.Sum(instance.Caddyfile().Body())
+	log.Printf("[INFO] Running configuration MD5 = %x\n", md5sum)
 
 	go func() {
 		tick := time.NewTicker(r.interval)
@@ -40,19 +44,26 @@ func hook(event caddy.EventName, info interface{}) error {
 		for {
 			select {
 			case <-tick.C:
-				corefile, err := caddy.LoadCaddyfile(r.instance.Caddyfile().ServerType())
+				corefile, err := caddy.LoadCaddyfile(instance.Caddyfile().ServerType())
 				if err != nil {
 					continue
 				}
 				s := md5.Sum(corefile.Body())
-				if s != r.sum {
-					_, err := r.instance.Restart(corefile)
+				if s != md5sum {
+					// Let not try to restart with the same file, even though it is wrong.
+					md5sum = s
+					// now lets consider that plugin will not be reload, unless appear in next config file
+					// change status iof usage will be reset in setup if the plugin appears in config file
+					r.usage = maybeUsed
+					_, err := instance.Restart(corefile)
 					if err != nil {
 						log.Printf("[ERROR] Corefile changed but reload failed: %s\n", err)
 						continue
 					}
-					// we are done, this hook gets called again with new instance
-					r.stopped = true
+					// we are done, if the plugin was not set used, then it is not.
+					if r.usage == maybeUsed {
+						r.usage = unused
+					}
 					return
 				}
 			case <-r.quit: