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076b8d4fba
Add OnReStartFailed which makes the health plugin stay up if the Corefile is corrupt and we revert to the previous version. Also needs a fix for the channel handling See #2659 Testing it will log the following when restarting with a corrupted Corefile ~~~ 2019-05-04T18:01:59.431Z [INFO] linux/amd64, go1.12.4, CoreDNS-1.5.0 linux/amd64, go1.12.4, [INFO] SIGUSR1: Reloading [INFO] Reloading [ERROR] Restart failed: Corefile:5 - Error during parsing: Unknown directive 'bdhfhdhj' [ERROR] SIGUSR1: starting with listener file descriptors: Corefile:5 - Error during parsing: Unknown directive 'bdhfhdhj' ~~~ After which the curl still works. This also needed a change to reset the channel used for the metrics go-routine which gets closed on shutdown, otherwise you'll see: ~~~ ^C[INFO] SIGINT: Shutting down panic: close of closed channel goroutine 90 [running]: github.com/coredns/coredns/plugin/health.(*health).OnFinalShutdown(0xc000089bc0, 0xc000063d88, 0x4afe6d) ~~~ Signed-off-by: Miek Gieben <miek@miek.nl>
71 lines
1.2 KiB
Go
71 lines
1.2 KiB
Go
// Package health implements an HTTP handler that responds to health checks.
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package health
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import (
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"io"
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"net"
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"net/http"
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"time"
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clog "github.com/coredns/coredns/plugin/pkg/log"
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)
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var log = clog.NewWithPlugin("health")
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// Health implements healthchecks by exporting a HTTP endpoint.
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type health struct {
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Addr string
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lameduck time.Duration
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ln net.Listener
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nlSetup bool
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mux *http.ServeMux
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stop chan bool
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}
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func (h *health) OnStartup() error {
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if h.Addr == "" {
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h.Addr = ":8080"
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}
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h.stop = make(chan bool)
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ln, err := net.Listen("tcp", h.Addr)
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if err != nil {
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return err
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}
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h.ln = ln
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h.mux = http.NewServeMux()
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h.nlSetup = true
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h.mux.HandleFunc("/health", func(w http.ResponseWriter, r *http.Request) {
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// We're always healthy.
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w.WriteHeader(http.StatusOK)
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io.WriteString(w, "OK")
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return
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})
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go func() { http.Serve(h.ln, h.mux) }()
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go func() { h.overloaded() }()
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return nil
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}
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func (h *health) OnFinalShutdown() error {
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if !h.nlSetup {
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return nil
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}
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if h.lameduck > 0 {
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log.Infof("Going into lameduck mode for %s", h.lameduck)
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time.Sleep(h.lameduck)
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}
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h.ln.Close()
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h.nlSetup = false
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close(h.stop)
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return nil
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}
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