Lighthouse reload support (#649)

Co-authored-by: John Maguire <contact@johnmaguire.me>

punchy.go

@@ -1,34 +1,89 @@
 package nebula
 
 import (
+	"sync/atomic"
 	"time"
 
+	"github.com/sirupsen/logrus"
 	"github.com/slackhq/nebula/config"
 )
 
 type Punchy struct {
-	Punch   bool
-	Respond bool
-	Delay   time.Duration
+	atomicPunch   int32
+	atomicRespond int32
+	atomicDelay   time.Duration
+	l             *logrus.Logger
 }
 
-func NewPunchyFromConfig(c *config.C) *Punchy {
-	p := &Punchy{}
+func NewPunchyFromConfig(l *logrus.Logger, c *config.C) *Punchy {
+	p := &Punchy{l: l}
 
-	if c.IsSet("punchy.punch") {
-		p.Punch = c.GetBool("punchy.punch", false)
-	} else {
-		// Deprecated fallback
-		p.Punch = c.GetBool("punchy", false)
-	}
+	p.reload(c, true)
+	c.RegisterReloadCallback(func(c *config.C) {
+		p.reload(c, false)
+	})
 
-	if c.IsSet("punchy.respond") {
-		p.Respond = c.GetBool("punchy.respond", false)
-	} else {
-		// Deprecated fallback
-		p.Respond = c.GetBool("punch_back", false)
-	}
-
-	p.Delay = c.GetDuration("punchy.delay", time.Second)
 	return p
 }
+
+func (p *Punchy) reload(c *config.C, initial bool) {
+	if initial {
+		var yes bool
+		if c.IsSet("punchy.punch") {
+			yes = c.GetBool("punchy.punch", false)
+		} else {
+			// Deprecated fallback
+			yes = c.GetBool("punchy", false)
+		}
+
+		if yes {
+			atomic.StoreInt32(&p.atomicPunch, 1)
+		} else {
+			atomic.StoreInt32(&p.atomicPunch, 0)
+		}
+
+	} else if c.HasChanged("punchy.punch") || c.HasChanged("punchy") {
+		//TODO: it should be relatively easy to support this, just need to be able to cancel the goroutine and boot it up from here
+		p.l.Warn("Changing punchy.punch with reload is not supported, ignoring.")
+	}
+
+	if initial || c.HasChanged("punchy.respond") || c.HasChanged("punch_back") {
+		var yes bool
+		if c.IsSet("punchy.respond") {
+			yes = c.GetBool("punchy.respond", false)
+		} else {
+			// Deprecated fallback
+			yes = c.GetBool("punch_back", false)
+		}
+
+		if yes {
+			atomic.StoreInt32(&p.atomicRespond, 1)
+		} else {
+			atomic.StoreInt32(&p.atomicRespond, 0)
+		}
+
+		if !initial {
+			p.l.Infof("punchy.respond changed to %v", p.GetRespond())
+		}
+	}
+
+	//NOTE: this will not apply to any in progress operations, only the next one
+	if initial || c.HasChanged("punchy.delay") {
+		atomic.StoreInt64((*int64)(&p.atomicDelay), (int64)(c.GetDuration("punchy.delay", time.Second)))
+		if !initial {
+			p.l.Infof("punchy.delay changed to %s", p.GetDelay())
+		}
+	}
+}
+
+func (p *Punchy) GetPunch() bool {
+	return atomic.LoadInt32(&p.atomicPunch) == 1
+}
+
+func (p *Punchy) GetRespond() bool {
+	return atomic.LoadInt32(&p.atomicRespond) == 1
+}
+
+func (p *Punchy) GetDelay() time.Duration {
+	return (time.Duration)(atomic.LoadInt64((*int64)(&p.atomicDelay)))
+}