Support sighup reload configuration files

Support podman service sighup reload configuration files(containers.conf, registries.conf, storage.conf).

Signed-off-by: Qi Wang <qiwan@redhat.com>

cmd/podman/system/service_abi.go

@@ -5,8 +5,12 @@ package system
 import (
 	"context"
 	"net"
+	"os"
+	"os/signal"
 	"strings"
 
+	"github.com/containers/podman/v2/cmd/podman/utils"
+	"github.com/containers/podman/v2/libpod"
 	api "github.com/containers/podman/v2/pkg/api/server"
 	"github.com/containers/podman/v2/pkg/domain/entities"
 	"github.com/containers/podman/v2/pkg/domain/infra"
@@ -39,6 +43,7 @@ func restService(opts entities.ServiceOptions, flags *pflag.FlagSet, cfg *entiti
 		return err
 	}
 
+	startWatcher(rt)
 	server, err := api.NewServerWithSettings(rt, opts.Timeout, listener)
 	if err != nil {
 		return err
@@ -55,3 +60,24 @@ func restService(opts entities.ServiceOptions, flags *pflag.FlagSet, cfg *entiti
 	}
 	return err
 }
+
+// startWatcher starts a new SIGHUP go routine for the current config.
+func startWatcher(rt *libpod.Runtime) {
+	// Setup the signal notifier
+	ch := make(chan os.Signal, 1)
+	signal.Notify(ch, utils.SIGHUP)
+
+	go func() {
+		for {
+			// Block until the signal is received
+			logrus.Debugf("waiting for SIGHUP to reload configuration")
+			<-ch
+			if err := rt.Reload(); err != nil {
+				logrus.Errorf("unable to reload configuration: %v", err)
+				continue
+			}
+		}
+	}()
+
+	logrus.Debugf("registered SIGHUP watcher for config")
+}

cmd/podman/utils/signals_linux.go

@@ -0,0 +1,14 @@
+// +build !windows
+
+package utils
+
+import (
+	"os"
+
+	"golang.org/x/sys/unix"
+)
+
+// Platform specific signal synonyms
+var (
+	SIGHUP os.Signal = unix.SIGHUP
+)

cmd/podman/utils/signals_windows.go

@@ -0,0 +1,14 @@
+// +build windows
+
+package utils
+
+import (
+	"os"
+
+	"golang.org/x/sys/windows"
+)
+
+// Platform specific signal synonyms
+var (
+	SIGHUP os.Signal = windows.SIGHUP
+)

libpod/runtime.go

@@ -10,6 +10,7 @@ import (
 	"syscall"
 
 	"github.com/containers/common/pkg/config"
+	"github.com/containers/image/v5/pkg/sysregistriesv2"
 	is "github.com/containers/image/v5/storage"
 	"github.com/containers/image/v5/types"
 	"github.com/containers/podman/v2/libpod/define"
@@ -17,6 +18,7 @@ import (
 	"github.com/containers/podman/v2/libpod/image"
 	"github.com/containers/podman/v2/libpod/lock"
 	"github.com/containers/podman/v2/pkg/cgroups"
+	"github.com/containers/podman/v2/pkg/registries"
 	"github.com/containers/podman/v2/pkg/rootless"
 	"github.com/containers/podman/v2/pkg/util"
 	"github.com/containers/storage"
@@ -816,3 +818,50 @@ func (r *Runtime) mergeDBConfig(dbConfig *DBConfig) {
 func (r *Runtime) EnableLabeling() bool {
 	return r.config.Containers.EnableLabeling
 }
+
+// Reload reloads the configurations files
+func (r *Runtime) Reload() error {
+	if err := r.reloadContainersConf(); err != nil {
+		return err
+	}
+	if err := r.reloadStorageConf(); err != nil {
+		return err
+	}
+	if err := reloadRegistriesConf(); err != nil {
+		return err
+	}
+	return nil
+}
+
+// reloadContainersConf reloads the containers.conf
+func (r *Runtime) reloadContainersConf() error {
+	config, err := config.Reload()
+	if err != nil {
+		return err
+	}
+	r.config = config
+	logrus.Infof("applied new containers configuration: %v", config)
+	return nil
+}
+
+// reloadRegistries reloads the registries.conf
+func reloadRegistriesConf() error {
+	sysregistriesv2.InvalidateCache()
+	registries, err := sysregistriesv2.GetRegistries(&types.SystemContext{SystemRegistriesConfPath: registries.SystemRegistriesConfPath()})
+	if err != nil {
+		return err
+	}
+	logrus.Infof("applied new registry configuration: %+v", registries)
+	return nil
+}
+
+// reloadStorageConf reloads the storage.conf
+func (r *Runtime) reloadStorageConf() error {
+	configFile, err := storage.DefaultConfigFile(rootless.IsRootless())
+	if err != nil {
+		return err
+	}
+	storage.ReloadConfigurationFile(configFile, &r.storageConfig)
+	logrus.Infof("applied new storage configuration: %v", r.storageConfig)
+	return nil
+}