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authorMatthew Heon <mheon@redhat.com>2020-10-13 14:00:35 -0400
committerMatthew Heon <mheon@redhat.com>2020-10-13 14:21:19 -0400
commitf58d2f5e75b4982774509847c18b39f4a50fd5be (patch)
tree53096a2bed60f6805ac0b25dcb297b7a0bd0078e
parent83e6e4ccdd925fa25500cff9e4b631b2c5d157cb (diff)
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Enforce LIFO ordering for shutdown handlers
This allows us to run both the Libpod and Server handlers at the same time without unregistering one. Also, pass the signal that killed us into the handlers, in case they want to use it to determine what to do (e.g. what exit code to set). Signed-off-by: Matthew Heon <mheon@redhat.com>
-rw-r--r--libpod/runtime.go2
-rw-r--r--libpod/shutdown/handler.go42
-rw-r--r--pkg/api/server/server.go5
3 files changed, 32 insertions, 17 deletions
diff --git a/libpod/runtime.go b/libpod/runtime.go
index 1118264f0..ccd920ab0 100644
--- a/libpod/runtime.go
+++ b/libpod/runtime.go
@@ -183,7 +183,7 @@ func newRuntimeFromConfig(ctx context.Context, conf *config.Config, options ...R
return nil, err
}
- if err := shutdown.Register("libpod", func() error {
+ if err := shutdown.Register("libpod", func(sig os.Signal) error {
os.Exit(1)
return nil
}); err != nil {
diff --git a/libpod/shutdown/handler.go b/libpod/shutdown/handler.go
index 7abaf065b..87538dec9 100644
--- a/libpod/shutdown/handler.go
+++ b/libpod/shutdown/handler.go
@@ -11,17 +11,20 @@ import (
)
var (
- stopped bool
- sigChan chan os.Signal
- cancelChan chan bool
- handlers map[string]func() error
+ stopped bool
+ sigChan chan os.Signal
+ cancelChan chan bool
+ // Definitions of all on-shutdown handlers
+ handlers map[string]func(os.Signal) error
+ // Ordering that on-shutdown handlers will be invoked.
+ handlerOrder []string
shutdownInhibit sync.RWMutex
)
// 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 {
+ if sigChan != nil {
// Already running, do nothing.
return nil
}
@@ -43,9 +46,14 @@ func Start() error {
case sig := <-sigChan:
logrus.Infof("Received shutdown signal %v, terminating!", sig)
shutdownInhibit.Lock()
- for name, handler := range handlers {
+ for _, name := range handlerOrder {
+ handler, ok := handlers[name]
+ if !ok {
+ logrus.Errorf("Shutdown handler %s definition not found!", name)
+ continue
+ }
logrus.Infof("Invoking shutdown handler %s", name)
- if err := handler(); err != nil {
+ if err := handler(sig); err != nil {
logrus.Errorf("Error running shutdown handler %s: %v", name, err)
}
}
@@ -82,10 +90,11 @@ func Uninhibit() {
}
// Register registers a function that will be executed when Podman is terminated
-// by a signal.
-func Register(name string, handler func() error) error {
+// by a signal. Handlers are invoked LIFO - the last handler registered is the
+// first run.
+func Register(name string, handler func(os.Signal) error) error {
if handlers == nil {
- handlers = make(map[string]func() error)
+ handlers = make(map[string]func(os.Signal) error)
}
if _, ok := handlers[name]; ok {
@@ -93,6 +102,7 @@ func Register(name string, handler func() error) error {
}
handlers[name] = handler
+ handlerOrder = append([]string{name}, handlerOrder...)
return nil
}
@@ -100,14 +110,22 @@ func Register(name string, handler func() error) error {
// Unregister un-registers a given shutdown handler.
func Unregister(name string) error {
if handlers == nil {
- handlers = make(map[string]func() error)
+ return nil
}
if _, ok := handlers[name]; !ok {
- return errors.Errorf("no handler with name %s found", name)
+ return nil
}
delete(handlers, name)
+ newOrder := []string{}
+ for _, checkName := range handlerOrder {
+ if checkName != name {
+ newOrder = append(newOrder, checkName)
+ }
+ }
+ handlerOrder = newOrder
+
return nil
}
diff --git a/pkg/api/server/server.go b/pkg/api/server/server.go
index 24ad1874b..64008767b 100644
--- a/pkg/api/server/server.go
+++ b/pkg/api/server/server.go
@@ -185,14 +185,11 @@ func (s *APIServer) Serve() error {
if err := shutdown.Start(); err != nil {
return err
}
- if err := shutdown.Register("server", func() error {
+ if err := shutdown.Register("server", func(sig os.Signal) error {
return s.Shutdown()
}); err != nil {
return err
}
- // Unregister the libpod handler, which just calls exit(1).
- // Ignore errors if it doesn't exist.
- _ = shutdown.Unregister("libpod")
errChan := make(chan error, 1)