plugin/health: cleanups (#2811)

Small, trivial cleanup: got triggered because I saw a comment on how
health plugins polls other plugins which isn't true.

* Remove useless newHealth function
* healthParse -> parse
* Remove useless constants

Net deletion of code.
Signed-off-by: Miek Gieben <miek@miek.nl>

plugin/health/README.md

@@ -6,7 +6,7 @@
 
 ## Description
 
-Enabled process wide health endpoint. When CoreDNS is up and running this returns a 200 OK http
+Enabled process wide health endpoint. When CoreDNS is up and running this returns a 200 OK HTTP
 status code. The health is exported, by default, on port 8080/health .
 
 ## Syntax

plugin/health/health.go

@@ -12,7 +12,7 @@ import (
 
 var log = clog.NewWithPlugin("health")
 
-// Health implements healthchecks by polling plugins.
+// Health implements healthchecks by exporting a HTTP endpoint.
 type health struct {
 	Addr     string
 	lameduck time.Duration
@@ -24,14 +24,9 @@ type health struct {
 	stop chan bool
 }
 
-// newHealth returns a new initialized health.
-func newHealth(addr string) *health {
-	return &health{Addr: addr, stop: make(chan bool)}
-}
-
 func (h *health) OnStartup() error {
 	if h.Addr == "" {
-		h.Addr = defAddr
+		h.Addr = ":8080"
 	}
 
 	ln, err := net.Listen("tcp", h.Addr)
@@ -43,10 +38,10 @@ func (h *health) OnStartup() error {
 	h.mux = http.NewServeMux()
 	h.nlSetup = true
 
-	h.mux.HandleFunc(path, func(w http.ResponseWriter, r *http.Request) {
+	h.mux.HandleFunc("/health", func(w http.ResponseWriter, r *http.Request) {
 		// We're always healthy.
 		w.WriteHeader(http.StatusOK)
-		io.WriteString(w, ok)
+		io.WriteString(w, "OK")
 		return
 	})
 
@@ -74,9 +69,3 @@ func (h *health) OnFinalShutdown() error {
 	close(h.stop)
 	return nil
 }
-
-const (
-	ok      = "OK"
-	defAddr = ":8080"
-	path    = "/health"
-)

plugin/health/health_test.go

@@ -9,15 +9,14 @@ import (
 )
 
 func TestHealth(t *testing.T) {
-	h := newHealth(":0")
+	h := &health{Addr: ":0", stop: make(chan bool)}
 
 	if err := h.OnStartup(); err != nil {
 		t.Fatalf("Unable to startup the health server: %v", err)
 	}
 	defer h.OnFinalShutdown()
 
-	// Reconstruct the http address based on the port allocated by operating system.
-	address := fmt.Sprintf("http://%s%s", h.ln.Addr().String(), path)
+	address := fmt.Sprintf("http://%s%s", h.ln.Addr().String(), "/health")
 
 	response, err := http.Get(address)
 	if err != nil {
@@ -32,14 +31,13 @@ func TestHealth(t *testing.T) {
 	}
 	response.Body.Close()
 
-	if string(content) != ok {
+	if string(content) != "OK" {
 		t.Errorf("Invalid response body: expecting 'OK', got '%s'", string(content))
 	}
 }
 
 func TestHealthLameduck(t *testing.T) {
-	h := newHealth(":0")
-	h.lameduck = 250 * time.Millisecond
+	h := &health{Addr: ":0", stop: make(chan bool), lameduck: 250 * time.Millisecond}
 
 	if err := h.OnStartup(); err != nil {
 		t.Fatalf("Unable to startup the health server: %v", err)

plugin/health/overloaded.go

@@ -18,6 +18,7 @@ func (h *health) overloaded() {
 	}
 	url := "http://" + h.Addr
 	tick := time.NewTicker(1 * time.Second)
+	defer tick.Stop()
 
 	for {
 		select {
@@ -32,7 +33,6 @@ func (h *health) overloaded() {
 			HealthDuration.Observe(time.Since(start).Seconds())
 
 		case <-h.stop:
-			tick.Stop()
 			return
 		}
 	}

plugin/health/setup.go

@@ -19,13 +19,12 @@ func init() {
 }
 
 func setup(c *caddy.Controller) error {
-	addr, lame, err := healthParse(c)
+	addr, lame, err := parse(c)
 	if err != nil {
 		return plugin.Error("health", err)
 	}
 
-	h := newHealth(addr)
-	h.lameduck = lame
+	h := &health{Addr: addr, stop: make(chan bool), lameduck: lame}
 
 	c.OnStartup(func() error {
 		metrics.MustRegister(c, HealthDuration)
@@ -40,7 +39,7 @@ func setup(c *caddy.Controller) error {
 	return nil
 }
 
-func healthParse(c *caddy.Controller) (string, time.Duration, error) {
+func parse(c *caddy.Controller) (string, time.Duration, error) {
 	addr := ""
 	dur := time.Duration(0)
 	for c.Next() {

plugin/health/setup_test.go

@@ -30,7 +30,7 @@ func TestSetupHealth(t *testing.T) {
 
 	for i, test := range tests {
 		c := caddy.NewTestController("dns", test.input)
-		_, _, err := healthParse(c)
+		_, _, err := parse(c)
 
 		if test.shouldErr && err == nil {
 			t.Errorf("Test %d: Expected error but found none for input %s", i, test.input)