forked from coredns/coredns
/
health.go
96 lines (75 loc) · 1.75 KB
/
health.go
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// Package health implements an HTTP handler that responds to health checks.
package health
import (
"io"
"net"
"net/http"
"sync"
"time"
clog "github.com/coredns/coredns/plugin/pkg/log"
)
var log = clog.NewWithPlugin("health")
// Health implements healthchecks by polling plugins.
type health struct {
Addr string
lameduck time.Duration
ln net.Listener
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
}
// newHealth returns a new initialized health.
func newHealth(addr string) *health {
return &health{Addr: addr, stop: make(chan bool), pollstop: make(chan bool)}
}
func (h *health) OnStartup() error {
if h.Addr == "" {
h.Addr = defAddr
}
ln, err := net.Listen("tcp", h.Addr)
if err != nil {
return err
}
h.ln = ln
h.mux = http.NewServeMux()
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)
})
go func() { http.Serve(h.ln, h.mux) }()
go func() { h.overloaded() }()
return nil
}
func (h *health) OnRestart() error { return h.OnFinalShutdown() }
func (h *health) OnFinalShutdown() error {
if !h.nlSetup {
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)
}
h.ln.Close()
h.stop <- true
h.nlSetup = false
return nil
}
const (
ok = "OK"
defAddr = ":8080"
path = "/health"
)