Refactor controlplane into a go plugin (#833)

* Refactor controlplane into a go plugin

* Move vbox to controlplane package

docs/operating/multitenant.md

@@ -2,7 +2,7 @@
 
 ## Motivation
 
-By running Fn in multitenant mode, you can define independent pools of compute resources available to functions in the platform. By associating a function with a particular _load balancing group_, its invocations are guaranteed to execute on the compute resources assigned to that specific group. The pluggable _node pool manager_ abstraction provides a mechanism to scale compute resources dynamically, based on capacity requirements advertised by the load-balancing layer. Together with load balancer groups, it allows you to implement independent capacity and scaling policies for different sets of users or tenants. 
+By running Fn in multitenant mode, you can define independent pools of compute resources available to functions in the platform. By associating a function with a particular _load balancing group_, its invocations are guaranteed to execute on the compute resources assigned to that specific group. The pluggable _node pool manager_ abstraction provides a mechanism to scale compute resources dynamically, based on capacity requirements advertised by the load-balancing layer. Together with load balancer groups, it allows you to implement independent capacity and scaling policies for different sets of users or tenants.
 
 ## Create certificates
 
@@ -56,6 +56,7 @@ but the GRPC port is 9190.
 Grap the runner address and put in as value for the `FN_RUNNER_ADDRESSES` env variable.
 
 ```bash
+go build -o noop.so poolmanager/server/controlplane/plugin/noop.go
 go build -o fnnpm poolmanager/server/main.go
 
 FN_LOG_LEVEL=DEBUG \
@@ -64,6 +65,7 @@ FN_NODE_CERT_KEY=key.pem  \
 FN_NODE_CERT_AUTHORITY=cert.pem  \
 FN_PORT=8083  \
 FN_RUNNER_ADDRESSES=<RUNNER_ADDRESS_HERE>:9190 \
+CONTROL_PLANE_SO=noop.so \
 ./fnnpm
 ```
 

poolmanager/manager.go

@@ -8,7 +8,7 @@ import (
 	"sync"
 
 	model "github.com/fnproject/fn/poolmanager/grpc"
-	"github.com/fnproject/fn/poolmanager/server/cp"
+	"github.com/fnproject/fn/poolmanager/server/controlplane"
 	"github.com/sirupsen/logrus"
 )
 
@@ -32,12 +32,12 @@ type Predictor interface {
 type capacityManager struct {
 	ctx              context.Context
 	mx               sync.RWMutex
-	cp               cp.ControlPlane
+	cp               controlplane.ControlPlane
 	lbg              map[string]LBGroup
 	predictorFactory func() Predictor
 }
 
-func NewCapacityManager(ctx context.Context, cp cp.ControlPlane, opts ...func(*capacityManager) error) (CapacityManager, error) {
+func NewCapacityManager(ctx context.Context, cp controlplane.ControlPlane, opts ...func(*capacityManager) error) (CapacityManager, error) {
 	cm := &capacityManager{
 		ctx:              ctx,
 		cp:               cp,
@@ -107,7 +107,7 @@ type lbGroup struct {
 
 	// Attributes for managing runner pool membership
 	run_mx sync.RWMutex
-	cp     cp.ControlPlane
+	cp     controlplane.ControlPlane
 
 	current_capacity int64              // Of all active runners
 	target_capacity  int64              // All active runners plus any we've already asked for
@@ -140,7 +140,7 @@ type runner struct {
 	kill_after time.Time
 }
 
-func newLBGroup(lbgid string, ctx context.Context, cp cp.ControlPlane, predictorFactory func() Predictor) LBGroup {
+func newLBGroup(lbgid string, ctx context.Context, cp controlplane.ControlPlane, predictorFactory func() Predictor) LBGroup {
 	lbg := &lbGroup{
 		ctx:           ctx,
 		id:            lbgid,
@@ -296,20 +296,20 @@ func (lbg *lbGroup) target(ts time.Time, target int64) {
 
 		if desiredScale > lbg.target_capacity {
 			// We still need additional capacity
-			wanted := math.Min(math.Ceil(float64(target-lbg.target_capacity)/cp.CAPACITY_PER_RUNNER), LARGEST_REQUEST_AT_ONCE)
+			wanted := math.Min(math.Ceil(float64(target-lbg.target_capacity)/controlplane.CapacityPerRunner), LARGEST_REQUEST_AT_ONCE)
 			asked_for, err := lbg.cp.ProvisionRunners(lbg.Id(), int(wanted)) // Send the request; they'll show up later
 			if err != nil {
 				// Some kind of error during attempt to scale up
 				logrus.WithError(err).Error("Error occured during attempt to scale up")
 				return
 			}
-			lbg.target_capacity += int64(asked_for) * cp.CAPACITY_PER_RUNNER
+			lbg.target_capacity += int64(asked_for) * controlplane.CapacityPerRunner
 		}
 
-	} else if desiredScale <= lbg.current_capacity-cp.CAPACITY_PER_RUNNER {
+	} else if desiredScale <= lbg.current_capacity-controlplane.CapacityPerRunner {
 		// Scale down.
 		// We pick a node to turn off and move it to the draining pool.
-		for target <= lbg.current_capacity-cp.CAPACITY_PER_RUNNER && len(lbg.active_runners) > 0 {
+		for target <= lbg.current_capacity-controlplane.CapacityPerRunner && len(lbg.active_runners) > 0 {
 			// Begin with the one we added last.
 			runner := lbg.active_runners[len(lbg.active_runners)-1]
 			logrus.Infof("Marking runner %v at %v for draindown", runner.id, runner.address)

poolmanager/server/controlplane/controlplane.go

@@ -0,0 +1,20 @@
+/*
+	Interface between the Node Pool Manager and the Control Plane
+*/
+
+package controlplane
+
+const CapacityPerRunner = 4096
+
+type Runner struct {
+	Id      string
+	Address string
+	// Other: certs etc here as managed and installed by CP
+	Capacity int64
+}
+
+type ControlPlane interface {
+	GetLBGRunners(lgbId string) ([]*Runner, error)
+	ProvisionRunners(lgbId string, n int) (int, error)
+	RemoveRunner(lbgId string, id string) error
+}

poolmanager/server/controlplane/plugin/noop.go

@@ -1,56 +1,47 @@
-/*
+/**
-	Interface between the Node Pool Manager and the Control Plane
+ * Dummy implementation for the controlplane that just adds delays
-*/
+ */
-
+package main
-package cp
 
 import (
 	"crypto/rand"
 	"fmt"
 	"log"
+	"os"
+	"strings"
 	"sync"
 	"time"
+
+	"github.com/fnproject/fn/poolmanager/server/controlplane"
 )
 
-type Runner struct {
+const (
-	Id      string
+	EnvFixedRunners = "FN_RUNNER_ADDRESSES"
-	Address string
+)
-	// Other: certs etc here as managed and installed by CP
-	Capacity int64
-}
-
-const CAPACITY_PER_RUNNER = 4096
-
-type ControlPlane interface {
-	GetLBGRunners(lgbId string) ([]*Runner, error)
-	ProvisionRunners(lgbId string, n int) (int, error)
-	RemoveRunner(lbgId string, id string) error
-}
-
-type controlPlane struct {
-	mx sync.RWMutex
-
-	runners map[string][]*Runner
 
+type noopControlPlane struct {
+	mx           sync.RWMutex
+	runners      map[string][]*controlplane.Runner
 	_fakeRunners []string
 }
 
 const REQUEST_DURATION = 5 * time.Second
 
-func NewControlPlane(fakeRunners []string) ControlPlane {
+func init() {
-	cp := &controlPlane{
+	ControlPlane = noopControlPlane{
-		runners: make(map[string][]*Runner),
+		runners:      make(map[string][]*controlplane.Runner),
-
+		_fakeRunners: strings.Split(getEnv(EnvFixedRunners), ","),
-		_fakeRunners: fakeRunners,
 	}
-	return cp
 }
 
-func (cp *controlPlane) GetLBGRunners(lbgId string) ([]*Runner, error) {
+func main() {
+}
+
+func (cp *noopControlPlane) GetLBGRunners(lbgId string) ([]*controlplane.Runner, error) {
 	cp.mx.RLock()
 	defer cp.mx.RUnlock()
 
-	runners := make([]*Runner, 0)
+	runners := make([]*controlplane.Runner, 0)
 	if hosts, ok := cp.runners[lbgId]; ok {
 		for _, host := range hosts {
 			runners = append(runners, host) // In this CP implementation, a Runner is an immutable thing, so passing the pointer is fine
@@ -60,7 +51,7 @@ func (cp *controlPlane) GetLBGRunners(lbgId string) ([]*Runner, error) {
 	return runners, nil
 }
 
-func (cp *controlPlane) ProvisionRunners(lbgId string, n int) (int, error) {
+func (cp *noopControlPlane) ProvisionRunners(lbgId string, n int) (int, error) {
 	// Simulate some small amount of time for the CP to service this request
 	go func() {
 		time.Sleep(REQUEST_DURATION)
@@ -69,7 +60,7 @@ func (cp *controlPlane) ProvisionRunners(lbgId string, n int) (int, error) {
 
 		runners, ok := cp.runners[lbgId]
 		if !ok {
-			runners = make([]*Runner, 0)
+			runners = make([]*controlplane.Runner, 0)
 		}
 		for i := 0; i < n; i++ {
 			runners = append(runners, cp.makeRunners(lbgId)...)
@@ -81,9 +72,9 @@ func (cp *controlPlane) ProvisionRunners(lbgId string, n int) (int, error) {
 }
 
 // Make runner(s)
-func (cp *controlPlane) makeRunners(lbg string) []*Runner {
+func (cp *noopControlPlane) makeRunners(lbg string) []*controlplane.Runner {
 
-	var runners []*Runner
+	var runners []*controlplane.Runner
 	for _, fakeRunner := range cp._fakeRunners {
 
 		b := make([]byte, 16)
@@ -94,10 +85,10 @@ func (cp *controlPlane) makeRunners(lbg string) []*Runner {
 
 		uuid := fmt.Sprintf("%X-%X-%X-%X-%X", b[0:4], b[4:6], b[6:8], b[8:10], b[10:])
 
-		runners = append(runners, &Runner{
+		runners = append(runners, &controlplane.Runner{
 			Id:       uuid,
 			Address:  fakeRunner,
-			Capacity: CAPACITY_PER_RUNNER,
+			Capacity: controlplane.CapacityPerRunner,
 		})
 	}
 	return runners
@@ -106,12 +97,12 @@ func (cp *controlPlane) makeRunners(lbg string) []*Runner {
 // Ditch a runner from the pool.
 // We do this immediately - no point modelling a wait here
 // note: if this actually took time, we'd want to detect this properly so as to not confuse the NPM
-func (cp *controlPlane) RemoveRunner(lbgId string, id string) error {
+func (cp *noopControlPlane) RemoveRunner(lbgId string, id string) error {
 	cp.mx.Lock()
 	defer cp.mx.Unlock()
 
 	if runners, ok := cp.runners[lbgId]; ok {
-		newRunners := make([]*Runner, 0)
+		newRunners := make([]*controlplane.Runner, 0)
 		for _, host := range runners {
 			if host.Id != id {
 				newRunners = append(newRunners, host)
@@ -121,3 +112,13 @@ func (cp *controlPlane) RemoveRunner(lbgId string, id string) error {
 	}
 	return nil
 }
+
+func getEnv(key string) string {
+	value, ok := os.LookupEnv(key)
+	if !ok {
+		log.Panicf("Missing config key: %v", key)
+	}
+	return value
+}
+
+var ControlPlane noopControlPlane

poolmanager/server/controlplane/vbox.go

@@ -1,4 +1,4 @@
-package cp
+package controlplane
 
 import (
 	"bytes"

poolmanager/server/main.go

@@ -9,7 +9,7 @@ import (
 
 	"github.com/fnproject/fn/poolmanager"
 	model "github.com/fnproject/fn/poolmanager/grpc"
-	"github.com/fnproject/fn/poolmanager/server/cp"
+	"github.com/fnproject/fn/poolmanager/server/controlplane"
 
 	"crypto/tls"
 	"crypto/x509"
@@ -19,7 +19,7 @@ import (
 	"log"
 	"os"
 	"path/filepath"
-	"strings"
+	"plugin"
 
 	"github.com/sirupsen/logrus"
 	"google.golang.org/grpc/credentials"
@@ -30,7 +30,7 @@ type npmService struct {
 	capMan poolmanager.CapacityManager
 }
 
-func newNPMService(ctx context.Context, cp cp.ControlPlane) *npmService {
+func newNPMService(ctx context.Context, cp controlplane.ControlPlane) *npmService {
 	cm, err := poolmanager.NewCapacityManager(ctx, cp)
 	if err != nil {
 		logrus.Panic("Cannot construct capacity manager")
@@ -66,11 +66,11 @@ func (npm *npmService) GetLBGroup(ctx context.Context, gid *model.LBGroupId) (*m
 
 const (
 	// Certificates to communicate with other FN nodes
-	EnvCert         = "FN_NODE_CERT"
+	EnvCert        = "FN_NODE_CERT"
-	EnvCertKey      = "FN_NODE_CERT_KEY"
+	EnvCertKey     = "FN_NODE_CERT_KEY"
-	EnvCertAuth     = "FN_NODE_CERT_AUTHORITY"
+	EnvCertAuth    = "FN_NODE_CERT_AUTHORITY"
-	EnvPort         = "FN_PORT"
+	EnvPort        = "FN_PORT"
-	EnvFixedRunners = "FN_RUNNER_ADDRESSES"
+	ControlPlaneSO = "CONTROL_PLANE_SO"
 )
 
 func getAndCheckFile(envVar string) (string, error) {
@@ -116,6 +116,27 @@ func createGrpcCreds(cert string, key string, ca string) (grpc.ServerOption, err
 	return grpc.Creds(creds), nil
 }
 
+func newPluggableControlPlane() controlplane.ControlPlane {
+	pluginLocation := getEnv(ControlPlaneSO)
+	controlPlanePlugin, err := plugin.Open(pluginLocation)
+
+	if err != nil {
+		panic(err)
+	}
+
+	cpSymbol, err := controlPlanePlugin.Lookup("ControlPlane")
+
+	if err != nil {
+		panic(err)
+	}
+
+	cp := cpSymbol.(controlplane.ControlPlane)
+
+	logrus.Infof("Started controlplane : %s", cp)
+
+	return cp
+}
+
 func main() {
 	level, err := logrus.ParseLevel(getEnv("FN_LOG_LEVEL"))
 	if err != nil {
@@ -146,8 +167,7 @@ func main() {
 
 	logrus.Info("Starting Node Pool Manager gRPC service")
 
-	fakeRunners := strings.Split(getEnv(EnvFixedRunners), ",")
+	svc := newNPMService(context.Background(), newPluggableControlPlane())
-	svc := newNPMService(context.Background(), cp.NewControlPlane(fakeRunners))
 	model.RegisterNodePoolScalerServer(gRPCServer, svc)
 	model.RegisterRunnerManagerServer(gRPCServer, svc)