Add a shutdown signal handler #7999
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| Original file line number | Diff line number | Diff line change | ||||||
|---|---|---|---|---|---|---|---|---|
| @@ -0,0 +1,113 @@ | ||||||||
| package shutdown | ||||||||
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| import ( | ||||||||
| "os" | ||||||||
| "os/signal" | ||||||||
| "sync" | ||||||||
| "syscall" | ||||||||
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||||||||
| "github.com/pkg/errors" | ||||||||
| "github.com/sirupsen/logrus" | ||||||||
| ) | ||||||||
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||||||||
| var ( | ||||||||
| stopped bool | ||||||||
| sigChan chan os.Signal | ||||||||
| cancelChan chan bool | ||||||||
| handlers map[string]func() error | ||||||||
| shutdownInhibit sync.RWMutex | ||||||||
| ) | ||||||||
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||||||||
| // Start begins handling SIGTERM and SIGINT and will run the given on-signal | ||||||||
| // handlers when one is called. This can be cancelled by calling Stop(). | ||||||||
| func Start() error { | ||||||||
| if sigChan != nil && !stopped { | ||||||||
| // Already running, do nothing. | ||||||||
| return nil | ||||||||
| } | ||||||||
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| sigChan = make(chan os.Signal, 1) | ||||||||
| cancelChan = make(chan bool, 1) | ||||||||
| stopped = false | ||||||||
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| signal.Notify(sigChan, syscall.SIGINT, syscall.SIGTERM) | ||||||||
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| go func() { | ||||||||
| select { | ||||||||
| case <-cancelChan: | ||||||||
| signal.Stop(sigChan) | ||||||||
| close(sigChan) | ||||||||
| close(cancelChan) | ||||||||
| stopped = true | ||||||||
| return | ||||||||
| case sig := <-sigChan: | ||||||||
| logrus.Infof("Received shutdown signal %v, terminating!", sig) | ||||||||
| shutdownInhibit.Lock() | ||||||||
| for name, handler := range handlers { | ||||||||
| logrus.Infof("Invoking shutdown handler %s", name) | ||||||||
| if err := handler(); err != nil { | ||||||||
| logrus.Errorf("Error running shutdown handler %s: %v", name, err) | ||||||||
| } | ||||||||
| } | ||||||||
| shutdownInhibit.Unlock() | ||||||||
| return | ||||||||
| } | ||||||||
| }() | ||||||||
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||||||||
| return nil | ||||||||
| } | ||||||||
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||||||||
| // Stop the shutdown signal handler. | ||||||||
| func Stop() error { | ||||||||
| if cancelChan == nil { | ||||||||
| return errors.New("shutdown signal handler has not yet been started") | ||||||||
| } | ||||||||
| if stopped { | ||||||||
| return nil | ||||||||
| } | ||||||||
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| cancelChan <- true | ||||||||
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||||||||
| return nil | ||||||||
| } | ||||||||
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||||||||
| // Temporarily inhibit signals from shutting down Libpod. | ||||||||
| func Inhibit() { | ||||||||
| shutdownInhibit.RLock() | ||||||||
| } | ||||||||
|
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||||||||
| // Stop inhibiting signals from shutting down Libpod. | ||||||||
| func Uninhibit() { | ||||||||
| shutdownInhibit.RUnlock() | ||||||||
| } | ||||||||
|
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||||||||
| // Register registers a function that will be executed when Podman is terminated | ||||||||
| // by a signal. | ||||||||
| func Register(name string, handler func() error) error { | ||||||||
| if handlers == nil { | ||||||||
| handlers = make(map[string]func() error) | ||||||||
| } | ||||||||
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||||||||
| if _, ok := handlers[name]; ok { | ||||||||
| return errors.Errorf("handler with name %s already exists", name) | ||||||||
| } | ||||||||
|
Comment on lines
+100
to
+102
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Suggested change
Why not just reset handler to new func? There was a problem hiding this comment. I'd like to allow multiple handlers at the same time - theoretically the Libpod handler could run after the server handler and do any extra shutdown needed there. |
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| handlers[name] = handler | ||||||||
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| return nil | ||||||||
| } | ||||||||
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||||||||
| // Unregister un-registers a given shutdown handler. | ||||||||
| func Unregister(name string) error { | ||||||||
| if handlers == nil { | ||||||||
| handlers = make(map[string]func() error) | ||||||||
| } | ||||||||
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||||||||
| if _, ok := handlers[name]; !ok { | ||||||||
| return errors.Errorf("no handler with name %s found", name) | ||||||||
| } | ||||||||
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| delete(handlers, name) | ||||||||
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| return nil | ||||||||
| } | ||||||||
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It would appear to be a race on reading/setting
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Let me just remove that, it's not important that we be able to restart the handler right now.