diff options
| -rw-r--r-- | plugin.md | 5 | ||||
| -rw-r--r-- | plugin/erratic/README.md | 4 | ||||
| -rw-r--r-- | plugin/erratic/health.go | 14 | ||||
| -rw-r--r-- | plugin/health/README.md | 39 | ||||
| -rw-r--r-- | plugin/health/health.go | 28 | ||||
| -rw-r--r-- | plugin/health/health_test.go | 28 | ||||
| -rw-r--r-- | plugin/health/healther.go | 36 | ||||
| -rw-r--r-- | plugin/health/setup.go | 27 | ||||
| -rw-r--r-- | plugin/kubernetes/README.md | 6 | ||||
| -rw-r--r-- | plugin/kubernetes/health.go | 4 |
10 files changed, 18 insertions, 173 deletions
@@ -59,10 +59,7 @@ When exporting metrics the *Namespace* should be `plugin.Namespace` (="coredns") *Subsystem* should be the name of the plugin. The README.md for the plugin should then also contain a *Metrics* section detailing the metrics. -If the plugin supports dynamic health reporting it should also have *Health* section detailing on -some of its inner workings. - -If the plugins supports signalling readiness it should have a *Ready* section detailing how it +If the plugin supports signalling readiness it should have a *Ready* section detailing how it works. ## Documentation diff --git a/plugin/erratic/README.md b/plugin/erratic/README.md index a731bed0f..e3bd79ae8 100644 --- a/plugin/erratic/README.md +++ b/plugin/erratic/README.md @@ -33,10 +33,6 @@ erratic { In case of a zone transfer and truncate the final SOA record *isn't* added to the response. -## Health - -This plugin implements dynamic health checking. For every dropped query it turns unhealthy. - ## Ready This plugin reports readiness to the ready plugin. diff --git a/plugin/erratic/health.go b/plugin/erratic/health.go deleted file mode 100644 index 1d9625e16..000000000 --- a/plugin/erratic/health.go +++ /dev/null @@ -1,14 +0,0 @@ -package erratic - -import ( - "sync/atomic" -) - -// Health implements the health.Healther interface. -func (e *Erratic) Health() bool { - q := atomic.LoadUint64(&e.q) - if e.drop > 0 && q%e.drop == 0 { - return false - } - return true -} diff --git a/plugin/health/README.md b/plugin/health/README.md index 6d402c4a8..68afeac06 100644 --- a/plugin/health/README.md +++ b/plugin/health/README.md @@ -6,9 +6,8 @@ ## Description -By enabling *health* any plugin that implements -[health.Healther interface](https://godoc.org/github.com/coredns/coredns/plugin/health#Healther) -will be queried for it's health. The combined health is exported, by default, on port 8080/health . +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 @@ -17,12 +16,9 @@ health [ADDRESS] ~~~ Optionally takes an address; the default is `:8080`. The health path is fixed to `/health`. The -health endpoint returns a 200 response code and the word "OK" when this server is healthy. It returns -a 503. *health* periodically (1s) polls plugins that exports health information. If any of the -plugins signals that it is unhealthy, the server will go unhealthy too. Each plugin that supports -health checks has a section "Health" in their README. +health endpoint returns a 200 response code and the word "OK" when this server is healthy. -More options can be set with this extended syntax: +An extra option can be set with this extended syntax: ~~~ health [ADDRESS] { @@ -33,8 +29,8 @@ health [ADDRESS] { * Where `lameduck` will make the process unhealthy then *wait* for **DURATION** before the process shuts down. -If you have multiple Server Blocks and need to export health for each of the plugins, you must run -health endpoints on different ports: +If you have multiple Server Blocks, *health* should only be enabled in one of them (as it is process +wide). If you really need multiple endpoints, you must run health endpoints on different ports: ~~~ corefile com { @@ -48,21 +44,6 @@ net { } ~~~ -Note that if you format this in one server block you will get an error on startup, that the second -server can't setup the health plugin (on the same port). - -~~~ txt -com net { - whoami - erratic - health :8080 -} -~~~ - -## Plugins - -Any plugin that implements the Healther interface will be used to report health. - ## Metrics If monitoring is enabled (via the *prometheus* directive) then the following metric is exported: @@ -96,7 +77,7 @@ Set a lameduck duration of 1 second: ## Bugs -When reloading, the Health handler is stopped before the new server instance is started. -If that new server fails to start, then the initial server instance is still available and DNS queries still served, -but Health handler stays down. -Health will not reply HTTP request until a successful reload or a complete restart of CoreDNS. +When reloading, the health handler is stopped before the new server instance is started. If that +new server fails to start, then the initial server instance is still available and DNS queries still +served, but health handler stays down. Health will not reply HTTP request until a successful reload +or a complete restart of CoreDNS. diff --git a/plugin/health/health.go b/plugin/health/health.go index 7f35b0709..895704409 100644 --- a/plugin/health/health.go +++ b/plugin/health/health.go @@ -5,7 +5,6 @@ import ( "io" "net" "net/http" - "sync" "time" clog "github.com/coredns/coredns/plugin/pkg/log" @@ -22,18 +21,12 @@ type health struct { nlSetup bool mux *http.ServeMux - // A slice of Healthers that the health plugin will poll every second for their health status. - h []Healther - sync.RWMutex - ok bool // ok is the global boolean indicating an all healthy plugin stack - - stop chan bool - pollstop chan bool + stop chan bool } // newHealth returns a new initialized health. func newHealth(addr string) *health { - return &health{Addr: addr, stop: make(chan bool), pollstop: make(chan bool)} + return &health{Addr: addr, stop: make(chan bool)} } func (h *health) OnStartup() error { @@ -51,12 +44,10 @@ func (h *health) OnStartup() error { h.nlSetup = true h.mux.HandleFunc(path, func(w http.ResponseWriter, r *http.Request) { - if h.Ok() { - w.WriteHeader(http.StatusOK) - io.WriteString(w, ok) - return - } - w.WriteHeader(http.StatusServiceUnavailable) + // We're always healthy. + w.WriteHeader(http.StatusOK) + io.WriteString(w, ok) + return }) go func() { http.Serve(h.ln, h.mux) }() @@ -72,11 +63,6 @@ func (h *health) OnFinalShutdown() error { return nil } - // Stop polling plugins - h.pollstop <- true - // NACK health - h.SetOk(false) - if h.lameduck > 0 { log.Infof("Going into lameduck mode for %s", h.lameduck) time.Sleep(h.lameduck) @@ -84,8 +70,8 @@ func (h *health) OnFinalShutdown() error { h.ln.Close() - h.stop <- true h.nlSetup = false + close(h.stop) return nil } diff --git a/plugin/health/health_test.go b/plugin/health/health_test.go index acd06ea37..21433c975 100644 --- a/plugin/health/health_test.go +++ b/plugin/health/health_test.go @@ -6,43 +6,23 @@ import ( "net/http" "testing" "time" - - "github.com/coredns/coredns/plugin/erratic" ) func TestHealth(t *testing.T) { h := newHealth(":0") - h.h = append(h.h, &erratic.Erratic{}) if err := h.OnStartup(); err != nil { t.Fatalf("Unable to startup the health server: %v", err) } defer h.OnFinalShutdown() - go func() { - <-h.pollstop - return - }() - // Reconstruct the http address based on the port allocated by operating system. address := fmt.Sprintf("http://%s%s", h.ln.Addr().String(), path) - // Nothing set should return unhealthy response, err := http.Get(address) if err != nil { t.Fatalf("Unable to query %s: %v", address, err) } - if response.StatusCode != 503 { - t.Errorf("Invalid status code: expecting '503', got '%d'", response.StatusCode) - } - response.Body.Close() - - h.poll() - - response, err = http.Get(address) - if err != nil { - t.Fatalf("Unable to query %s: %v", address, err) - } if response.StatusCode != 200 { t.Errorf("Invalid status code: expecting '200', got '%d'", response.StatusCode) } @@ -60,18 +40,10 @@ func TestHealth(t *testing.T) { func TestHealthLameduck(t *testing.T) { h := newHealth(":0") h.lameduck = 250 * time.Millisecond - h.h = append(h.h, &erratic.Erratic{}) if err := h.OnStartup(); err != nil { t.Fatalf("Unable to startup the health server: %v", err) } - // Both these things are behind a sync.Once, fake reading from the channels. - go func() { - <-h.pollstop - <-h.stop - return - }() - h.OnFinalShutdown() } diff --git a/plugin/health/healther.go b/plugin/health/healther.go deleted file mode 100644 index 8bb6c907c..000000000 --- a/plugin/health/healther.go +++ /dev/null @@ -1,36 +0,0 @@ -package health - -// Healther interface needs to be implemented by each plugin willing to provide -// healthhceck information to the health plugin. Note this method should return -// quickly, i.e. just checking a boolean status, as it is called every second -// from the health plugin. -type Healther interface { - // Health returns a boolean indicating the health status of a plugin. - // False indicates unhealthy. - Health() bool -} - -// Ok returns the global health status of all plugin configured in this server. -func (h *health) Ok() bool { - h.RLock() - defer h.RUnlock() - return h.ok -} - -// SetOk sets the global health status of all plugin configured in this server. -func (h *health) SetOk(ok bool) { - h.Lock() - defer h.Unlock() - h.ok = ok -} - -// poll polls all healthers and sets the global state. -func (h *health) poll() { - for _, m := range h.h { - if !m.Health() { - h.SetOk(false) - return - } - } - h.SetOk(true) -} diff --git a/plugin/health/setup.go b/plugin/health/setup.go index 5a1725125..19aeba58d 100644 --- a/plugin/health/setup.go +++ b/plugin/health/setup.go @@ -5,7 +5,6 @@ import ( "net" "time" - "github.com/coredns/coredns/core/dnsserver" "github.com/coredns/coredns/plugin" "github.com/coredns/coredns/plugin/metrics" @@ -29,32 +28,6 @@ func setup(c *caddy.Controller) error { h.lameduck = lame c.OnStartup(func() error { - plugins := dnsserver.GetConfig(c).Handlers() - for _, p := range plugins { - if x, ok := p.(Healther); ok { - h.h = append(h.h, x) - } - } - return nil - }) - - c.OnStartup(func() error { - // Poll all middleware every second. - h.poll() - go func() { - for { - select { - case <-time.After(1 * time.Second): - h.poll() - case <-h.pollstop: - return - } - } - }() - return nil - }) - - c.OnStartup(func() error { metrics.MustRegister(c, HealthDuration) return nil }) diff --git a/plugin/kubernetes/README.md b/plugin/kubernetes/README.md index 552050b0b..672e167df 100644 --- a/plugin/kubernetes/README.md +++ b/plugin/kubernetes/README.md @@ -107,11 +107,6 @@ kubernetes [ZONES...] { This allows the querying pod to continue searching for the service in the search path. The search path could, for example, include another Kubernetes cluster. -## Health - -This plugin implements dynamic health checking. Currently this is limited to reporting healthy when -the API has synced. - ## Examples Handle all queries in the `cluster.local` zone. Connect to Kubernetes in-cluster. Also handle all @@ -144,7 +139,6 @@ kubernetes cluster.local { } ~~~ - ## stubDomains and upstreamNameservers Here we use the *forward* plugin to implement a stubDomain that forwards `example.local` to the nameserver `10.100.0.10:53`. diff --git a/plugin/kubernetes/health.go b/plugin/kubernetes/health.go deleted file mode 100644 index 243749210..000000000 --- a/plugin/kubernetes/health.go +++ /dev/null @@ -1,4 +0,0 @@ -package kubernetes - -// Health implements the health.Healther interface. -func (k *Kubernetes) Health() bool { return k.APIConn.HasSynced() } |