feature: add plugin framework which supports executing custom code at…

… plugin points like start and stop in life cyle of container and daemon

apis/plugins/ContainerPlugin.go

@@ -0,0 +1,22 @@
+package plugins
+
+import "io"
+
+// ContainerPlugin defines in which place a plugin will be triggered in container lifecycle
+type ContainerPlugin interface {
+	// PreCreate defines plugin point where recevives an container create request, in this plugin point user
+	// could change the container create body passed-in by http request body
+	PreCreate(io.ReadCloser) (io.ReadCloser, error)
+
+	// PreStart returns an array of PreStartHook which will pass to runc, in PreStartHook there is a Priority which
+	// used to sort the pre start array that pass to runc, network plugin hook has priority value 0.
+	PreStart(interface{}) (PreStartHook, error)
+}
+
+// PreStartHook defines the hook wrapper which will return priority and the hook info
+type PreStartHook interface {
+	// Priority returns priority of this hook, the bigger one will run first
+	Priority() []int
+	// Hook returns the real hook command
+	Hook() [][]string
+}

apis/plugins/DaemonPlugin.go

@@ -0,0 +1,12 @@
+package plugins
+
+// DaemonPlugin defines in which place does pouch daemon support plugin
+type DaemonPlugin interface {
+	// PreStartHook is invoked by pouch daemon before real start, in this hook user could start dfget proxy or other
+	// standalone process plugins
+	PreStartHook() error
+
+	// PreStopHook is invoked by pouch daemon before daemon process exit, not a promise if daemon is killed, in this
+	// hook user could stop the process or plugin started by PreStartHook
+	PreStopHook() error
+}

apis/server/container_bridge.go

@@ -16,6 +16,7 @@ import (
 
 	"github.com/go-openapi/strfmt"
 	"github.com/gorilla/mux"
+	"github.com/pkg/errors"
 )
 
 func (s *Server) removeContainers(ctx context.Context, rw http.ResponseWriter, req *http.Request) error {
@@ -114,8 +115,15 @@ func (s *Server) startContainerExec(ctx context.Context, rw http.ResponseWriter,
 
 func (s *Server) createContainer(ctx context.Context, rw http.ResponseWriter, req *http.Request) error {
 	config := &types.ContainerCreateConfig{}
+	reader := req.Body
+	var ex error
+	if s.ContainerPlugin != nil {
+		if reader, ex = s.ContainerPlugin.PreCreate(req.Body); ex != nil {
+			return errors.Wrapf(ex, "pre-create plugin piont execute failed")
+		}
+	}
 	// decode request body
-	if err := json.NewDecoder(req.Body).Decode(config); err != nil {
+	if err := json.NewDecoder(reader).Decode(config); err != nil {
 		return httputils.NewHTTPError(err, http.StatusBadRequest)
 	}
 	// validate request body

apis/server/server.go

@@ -9,6 +9,7 @@ import (
 	"strings"
 	"syscall"
 
+	"github.com/alibaba/pouch/apis/plugins"
 	"github.com/alibaba/pouch/daemon/config"
 	"github.com/alibaba/pouch/daemon/mgr"
 
@@ -18,13 +19,14 @@ import (
 
 // Server is a http server which serves restful api to client.
 type Server struct {
-	Config       config.Config
-	ContainerMgr mgr.ContainerMgr
-	SystemMgr    mgr.SystemMgr
-	ImageMgr     mgr.ImageMgr
-	VolumeMgr    mgr.VolumeMgr
-	NetworkMgr   mgr.NetworkMgr
-	listeners    []net.Listener
+	Config          config.Config
+	ContainerMgr    mgr.ContainerMgr
+	SystemMgr       mgr.SystemMgr
+	ImageMgr        mgr.ImageMgr
+	VolumeMgr       mgr.VolumeMgr
+	NetworkMgr      mgr.NetworkMgr
+	listeners       []net.Listener
+	ContainerPlugin plugins.ContainerPlugin
 }
 
 // Start setup route table and listen to specified address which currently only supports unix socket and tcp address.

daemon/config/config.go

@@ -66,4 +66,7 @@ type Config struct {
 
 	// CgroupParent is to set parent cgroup for all containers
 	CgroupParent string `json:"cgroup-parent,omitempty"`
+
+	// PluginPath is set the path where plugin so file put
+	PluginPath string `json:"plugin"`
 }

daemon/daemon.go

@@ -2,9 +2,12 @@ package daemon
 
 import (
 	"context"
+	"fmt"
 	"path"
+	"plugin"
 	"reflect"
 
+	"github.com/alibaba/pouch/apis/plugins"
 	"github.com/alibaba/pouch/apis/server"
 	cri "github.com/alibaba/pouch/cri/service"
 	"github.com/alibaba/pouch/ctrd"
@@ -13,24 +16,27 @@ import (
 	"github.com/alibaba/pouch/internal"
 	"github.com/alibaba/pouch/network/mode"
 	"github.com/alibaba/pouch/pkg/meta"
+	"github.com/pkg/errors"
 
 	"github.com/gorilla/mux"
 	"github.com/sirupsen/logrus"
 )
 
 // Daemon refers to a daemon.
 type Daemon struct {
-	config         config.Config
-	containerStore *meta.Store
-	containerd     *ctrd.Client
-	containerMgr   mgr.ContainerMgr
-	systemMgr      mgr.SystemMgr
-	imageMgr       mgr.ImageMgr
-	volumeMgr      mgr.VolumeMgr
-	networkMgr     mgr.NetworkMgr
-	criMgr         mgr.CriMgr
-	server         server.Server
-	criService     *cri.Service
+	config          config.Config
+	containerStore  *meta.Store
+	containerd      *ctrd.Client
+	containerMgr    mgr.ContainerMgr
+	systemMgr       mgr.SystemMgr
+	imageMgr        mgr.ImageMgr
+	volumeMgr       mgr.VolumeMgr
+	networkMgr      mgr.NetworkMgr
+	criMgr          mgr.CriMgr
+	server          server.Server
+	criService      *cri.Service
+	containerPlugin plugins.ContainerPlugin
+	daemonPlugin    plugins.DaemonPlugin
 }
 
 // router represents the router of daemon.
@@ -71,11 +77,55 @@ func NewDaemon(cfg config.Config) *Daemon {
 	}
 }
 
+func loadSymbolByName(p *plugin.Plugin, name string) (plugin.Symbol, error) {
+	s, err := p.Lookup(name)
+	if err != nil {
+		return nil, errors.Wrapf(err, "lookup plugin with name %s error", name)
+	}
+	return s, nil
+}
+
 // Run starts daemon.
 func (d *Daemon) Run() error {
 	ctx, cancel := context.WithCancel(context.Background())
 	defer cancel()
 
+	var s plugin.Symbol
+	var err error
+
+	if d.config.PluginPath != "" {
+		p, err := plugin.Open(d.config.PluginPath)
+		if err != nil {
+			return errors.Wrapf(err, "load plugin at %s error", d.config.PluginPath)
+		}
+
+		//load container plugin if exist
+		if s, err = loadSymbolByName(p, "DaemonPlugin"); err != nil {
+			return err
+		}
+		if daemonPlugin, ok := s.(plugins.DaemonPlugin); ok {
+			d.daemonPlugin = daemonPlugin
+		} else if s != nil {
+			return fmt.Errorf("not a container plugin at %s %q", d.config.PluginPath, s)
+		}
+
+		//load container plugin if exist
+		if s, err = loadSymbolByName(p, "ContainerPlugin"); err != nil {
+			return err
+		}
+		if containerPlugin, ok := s.(plugins.ContainerPlugin); ok {
+			d.containerPlugin = containerPlugin
+		} else if s != nil {
+			return fmt.Errorf("not a container plugin at %s %q", d.config.PluginPath, s)
+		}
+	}
+
+	if d.daemonPlugin != nil {
+		if err = d.daemonPlugin.PreStartHook(); err != nil {
+			return err
+		}
+	}
+
 	imageMgr, err := internal.GenImageMgr(&d.config, d)
 	if err != nil {
 		return err
@@ -118,12 +168,13 @@ func (d *Daemon) Run() error {
 	}
 
 	d.server = server.Server{
-		Config:       d.config,
-		ContainerMgr: containerMgr,
-		SystemMgr:    systemMgr,
-		ImageMgr:     imageMgr,
-		VolumeMgr:    volumeMgr,
-		NetworkMgr:   networkMgr,
+		Config:          d.config,
+		ContainerMgr:    containerMgr,
+		SystemMgr:       systemMgr,
+		ImageMgr:        imageMgr,
+		VolumeMgr:       volumeMgr,
+		NetworkMgr:      networkMgr,
+		ContainerPlugin: d.containerPlugin,
 	}
 
 	// init base network
@@ -166,6 +217,11 @@ func (d *Daemon) Run() error {
 	logrus.Infof("GRPC server stopped")
 	<-streamServerCloseCh
 	logrus.Infof("Stream server stopped")
+	if d.daemonPlugin != nil {
+		if err = d.daemonPlugin.PreStopHook(); err != nil {
+			logrus.Errorf("stop prehook execute error %v", err)
+		}
+	}
 	return nil
 }
 
@@ -212,3 +268,8 @@ func (d *Daemon) MetaStore() *meta.Store {
 func (d *Daemon) networkInit(ctx context.Context) error {
 	return mode.NetworkModeInit(ctx, d.config.NetworkConfg, d.networkMgr)
 }
+
+// ContainerPlugin returns the container plugin fetched from shared file
+func (d *Daemon) ContainerPlugin() plugins.ContainerPlugin {
+	return d.containerPlugin
+}

daemon/mgr/container.go

@@ -10,6 +10,7 @@ import (
 	"strings"
 	"time"
 
+	"github.com/alibaba/pouch/apis/plugins"
 	"github.com/alibaba/pouch/apis/types"
 	"github.com/alibaba/pouch/ctrd"
 	"github.com/alibaba/pouch/daemon/config"
@@ -112,22 +113,25 @@ type ContainerManager struct {
 
 	// monitor is used to handle container's event, eg: exit, stop and so on.
 	monitor *ContainerMonitor
+
+	containerPlugin plugins.ContainerPlugin
 }
 
 // NewContainerManager creates a brand new container manager.
-func NewContainerManager(ctx context.Context, store *meta.Store, cli *ctrd.Client, imgMgr ImageMgr, volMgr VolumeMgr, netMgr NetworkMgr, cfg *config.Config) (*ContainerManager, error) {
+func NewContainerManager(ctx context.Context, store *meta.Store, cli *ctrd.Client, imgMgr ImageMgr, volMgr VolumeMgr, netMgr NetworkMgr, cfg *config.Config, contPlugin plugins.ContainerPlugin) (*ContainerManager, error) {
 	mgr := &ContainerManager{
-		Store:         store,
-		NameToID:      collect.NewSafeMap(),
-		Client:        cli,
-		ImageMgr:      imgMgr,
-		VolumeMgr:     volMgr,
-		NetworkMgr:    netMgr,
-		IOs:           containerio.NewCache(),
-		ExecProcesses: collect.NewSafeMap(),
-		cache:         collect.NewSafeMap(),
-		Config:        cfg,
-		monitor:       NewContainerMonitor(),
+		Store:           store,
+		NameToID:        collect.NewSafeMap(),
+		Client:          cli,
+		ImageMgr:        imgMgr,
+		VolumeMgr:       volMgr,
+		NetworkMgr:      netMgr,
+		IOs:             containerio.NewCache(),
+		ExecProcesses:   collect.NewSafeMap(),
+		cache:           collect.NewSafeMap(),
+		Config:          cfg,
+		monitor:         NewContainerMonitor(),
+		containerPlugin: contPlugin,
 	}
 
 	mgr.Client.SetExitHooks(mgr.exitedAndRelease)
@@ -502,11 +506,20 @@ func (mgr *ContainerManager) Start(ctx context.Context, id, detachKeys string) (
 		s.Linux.CgroupsPath = filepath.Join(cgroupsParent, c.ID())
 	}
 
+	var customHooks plugins.PreStartHook
+	if mgr.containerPlugin != nil {
+		customHooks, err = mgr.containerPlugin.PreStart(c)
+		if err != nil {
+			return errors.Wrapf(err, "get pre-start hook error from container plugin")
+		}
+	}
+
 	sw := &SpecWrapper{
-		s:      s,
-		ctrMgr: mgr,
-		volMgr: mgr.VolumeMgr,
-		netMgr: mgr.NetworkMgr,
+		s:             s,
+		ctrMgr:        mgr,
+		volMgr:        mgr.VolumeMgr,
+		netMgr:        mgr.NetworkMgr,
+		preStartHooks: customHooks,
 	}
 
 	for _, setup := range SetupFuncs() {

daemon/mgr/spec.go

@@ -3,16 +3,19 @@ package mgr
 import (
 	"context"
 
+	"github.com/alibaba/pouch/apis/plugins"
+
 	specs "github.com/opencontainers/runtime-spec/specs-go"
 )
 
 // SpecWrapper wraps the container's specs and add manager operations.
 type SpecWrapper struct {
 	s *specs.Spec
 
-	ctrMgr ContainerMgr
-	volMgr VolumeMgr
-	netMgr NetworkMgr
+	ctrMgr        ContainerMgr
+	volMgr        VolumeMgr
+	netMgr        NetworkMgr
+	preStartHooks plugins.PreStartHook
 }
 
 // SetupFunc defines spec setup function type.