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Make middleware that sets up a (http) handler survive a graceful restart. We calls the middleware's Shutdown function(s). If restart fails the Start function is called again. * middleware/health: OK * middleware/pprof: OK * middleware/metrics: OK All restart OK.
94 lines
2.3 KiB
Go
94 lines
2.3 KiB
Go
package core
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import (
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"log"
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"os"
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"os/signal"
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"sync"
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"github.com/miekg/coredns/server"
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)
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// TrapSignals create signal handlers for all applicable signals for this
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// system. If your Go program uses signals, this is a rather invasive
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// function; best to implement them yourself in that case. Signals are not
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// required for the caddy package to function properly, but this is a
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// convenient way to allow the user to control this package of your program.
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func TrapSignals() {
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trapSignalsCrossPlatform()
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trapSignalsPosix()
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}
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// trapSignalsCrossPlatform captures SIGINT, which triggers forceful
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// shutdown that executes shutdown callbacks first. A second interrupt
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// signal will exit the process immediately.
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func trapSignalsCrossPlatform() {
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go func() {
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shutdown := make(chan os.Signal, 1)
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signal.Notify(shutdown, os.Interrupt)
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for i := 0; true; i++ {
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<-shutdown
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if i > 0 {
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log.Println("[INFO] SIGINT: Force quit")
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if PidFile != "" {
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os.Remove(PidFile)
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}
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os.Exit(1)
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}
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log.Println("[INFO] SIGINT: Shutting down")
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if PidFile != "" {
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os.Remove(PidFile)
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}
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go os.Exit(executeShutdownCallbacks("SIGINT"))
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}
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}()
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}
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// executeShutdownCallbacks executes the shutdown callbacks as initiated
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// by signame. It logs any errors and returns the recommended exit status.
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// This function is idempotent; subsequent invocations always return 0.
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func executeShutdownCallbacks(signame string) (exitCode int) {
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shutdownCallbacksOnce.Do(func() {
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serversMu.Lock()
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errs := server.ShutdownCallbacks(servers)
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serversMu.Unlock()
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if len(errs) > 0 {
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for _, err := range errs {
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log.Printf("[ERROR] %s shutdown: %v", signame, err)
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}
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exitCode = 1
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}
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})
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return
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}
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// executeStartupCallbacks executes the startup callbacks as initiated
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// by signame. This is used when on restart when the child failed to start and
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// all middleware executed their shutdown functions
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func executeStartupCallbacks(signame string) (exitCode int) {
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startupCallbacksOnce.Do(func() {
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serversMu.Lock()
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errs := server.StartupCallbacks(servers)
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serversMu.Unlock()
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if len(errs) > 0 {
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for _, err := range errs {
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log.Printf("[ERROR] %s shutdown: %v", signame, err)
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}
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exitCode = 1
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}
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})
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return
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}
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var (
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shutdownCallbacksOnce sync.Once
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startupCallbacksOnce sync.Once
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)
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