First draft of modifying RunnerListener to CallListener to get it closer to the action (and named better).

api/agent/agent.go

@@ -15,6 +15,7 @@ import (
 	"github.com/fnproject/fn/api/agent/drivers/docker"
 	"github.com/fnproject/fn/api/agent/protocol"
 	"github.com/fnproject/fn/api/common"
+	"github.com/fnproject/fn/api/extenders"
 	"github.com/fnproject/fn/api/id"
 	"github.com/fnproject/fn/api/models"
 	"github.com/opentracing/opentracing-go"
@@ -110,12 +111,14 @@ type Agent interface {
 
 	// Return the http.Handler used to handle Prometheus metric requests
 	PromHandler() http.Handler
+	AddCallListener(extenders.CallListener)
 }
 
 type agent struct {
 	// TODO maybe these should be on GetCall? idk. was getting bloated.
-	mq models.MessageQueue
+	mq            models.MessageQueue
-	ds models.Datastore
+	ds            models.Datastore
+	callListeners []extenders.CallListener
 
 	driver drivers.Driver
 
@@ -204,6 +207,11 @@ func (a *agent) Submit(callI Call) error {
 	// to make this remove the container asynchronously?
 	defer slot.Close() // notify our slot is free once we're done
 
+	err = a.fireBeforeCall(ctx, call.Model())
+	if err != nil {
+		return fmt.Errorf("BeforeCall: %v", err)
+	}
+
 	// TODO Start is checking the timer now, we could do it here, too.
 	err = call.Start(ctx)
 	if err != nil {
@@ -231,6 +239,11 @@ func (a *agent) Submit(callI Call) error {
 	ctx = opentracing.ContextWithSpan(context.Background(), span)
 	call.End(ctx, err)
 
+	err = a.fireAfterCall(ctx, call.Model())
+	if err != nil {
+		return fmt.Errorf("AfterCall: %v", err)
+	}
+
 	return err
 }
 

api/agent/call.go

@@ -331,7 +331,7 @@ func (c *call) End(ctx context.Context, err error) {
 	case context.DeadlineExceeded:
 		c.Status = "timeout"
 	default:
-		// XXX (reed): should we append the error to logs? Error field?
+		// XXX (reed): should we append the error to logs? Error field? (TR) think so, otherwise it's lost looks like?
 		c.Status = "error"
 	}
 

api/agent/listeners.go

@@ -0,0 +1,32 @@
+package agent
+
+import (
+	"context"
+
+	"github.com/fnproject/fn/api/extenders"
+	"github.com/fnproject/fn/api/models"
+)
+
+func (a *agent) AddCallListener(listener extenders.CallListener) {
+	a.callListeners = append(a.callListeners, listener)
+}
+
+func (a *agent) fireBeforeCall(ctx context.Context, call *models.Call) error {
+	for _, l := range a.callListeners {
+		err := l.BeforeCall(ctx, call)
+		if err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+func (a *agent) fireAfterCall(ctx context.Context, call *models.Call) error {
+	for _, l := range a.callListeners {
+		err := l.AfterCall(ctx, call)
+		if err != nil {
+			return err
+		}
+	}
+	return nil
+}

api/extenders/listeners.go

@@ -0,0 +1,31 @@
+package extenders
+
+import (
+	"context"
+
+	"github.com/fnproject/fn/api/models"
+)
+
+// AppListener is an interface used to inject custom code at key points in app lifecycle.
+type AppListener interface {
+	// BeforeAppCreate called right before creating App in the database
+	BeforeAppCreate(ctx context.Context, app *models.App) error
+	// AfterAppCreate called after creating App in the database
+	AfterAppCreate(ctx context.Context, app *models.App) error
+	// BeforeAppUpdate called right before updating App in the database
+	BeforeAppUpdate(ctx context.Context, app *models.App) error
+	// AfterAppUpdate called after updating App in the database
+	AfterAppUpdate(ctx context.Context, app *models.App) error
+	// BeforeAppDelete called right before deleting App in the database
+	BeforeAppDelete(ctx context.Context, app *models.App) error
+	// AfterAppDelete called after deleting App in the database
+	AfterAppDelete(ctx context.Context, app *models.App) error
+}
+
+// CallListener enables callbacks around Call events
+type CallListener interface {
+	// BeforeCall called before a function is executed
+	BeforeCall(ctx context.Context, call *models.Call) error
+	// AfterCall called after a function completes
+	AfterCall(ctx context.Context, call *models.Call) error
+}

api/server/app_listeners.go

@@ -3,27 +3,12 @@ package server
 import (
 	"context"
 
+	"github.com/fnproject/fn/api/extenders"
 	"github.com/fnproject/fn/api/models"
 )
 
-// AppListener is an interface used to inject custom code at key points in app lifecycle.
-type AppListener interface {
-	// BeforeAppCreate called right before creating App in the database
-	BeforeAppCreate(ctx context.Context, app *models.App) error
-	// AfterAppCreate called after creating App in the database
-	AfterAppCreate(ctx context.Context, app *models.App) error
-	// BeforeAppUpdate called right before updating App in the database
-	BeforeAppUpdate(ctx context.Context, app *models.App) error
-	// AfterAppUpdate called after updating App in the database
-	AfterAppUpdate(ctx context.Context, app *models.App) error
-	// BeforeAppDelete called right before deleting App in the database
-	BeforeAppDelete(ctx context.Context, app *models.App) error
-	// AfterAppDelete called after deleting App in the database
-	AfterAppDelete(ctx context.Context, app *models.App) error
-}
-
 // AddAppListener adds a listener that will be notified on App created.
-func (s *Server) AddAppListener(listener AppListener) {
+func (s *Server) AddAppListener(listener extenders.AppListener) {
 	s.appListeners = append(s.appListeners, listener)
 }
 

api/server/listeners.go

@@ -0,0 +1,8 @@
+package server
+
+import "github.com/fnproject/fn/api/extenders"
+
+// AddCallListener adds a listener that will be fired before and after a function is executed.
+func (s *Server) AddCallListener(listener extenders.CallListener) {
+	s.Agent.AddCallListener(listener)
+}

api/server/runner.go

@@ -27,8 +27,6 @@ func (s *Server) handleRequest(c *gin.Context) {
 		return
 	}
 
-	ctx := c.Request.Context()
-
 	r, routeExists := c.Get(api.Path)
 	if !routeExists {
 		r = "/"
@@ -39,11 +37,8 @@ func (s *Server) handleRequest(c *gin.Context) {
 		Path:    path.Clean(r.(string)),
 	}
 
-	s.FireBeforeDispatch(ctx, reqRoute)
-
 	s.serve(c, reqRoute.AppName, reqRoute.Path)
 
-	s.FireAfterDispatch(ctx, reqRoute)
 }
 
 // TODO it would be nice if we could make this have nothing to do with the gin.Context but meh
@@ -60,7 +55,6 @@ func (s *Server) serve(c *gin.Context, appName, path string) {
 		return
 	}
 
-	// TODO we could add FireBeforeDispatch right here with Call in hand
 	model := call.Model()
 	{ // scope this, to disallow ctx use outside of this scope. add id for handleErrorResponse logger
 		ctx, _ := common.LoggerWithFields(c.Request.Context(), logrus.Fields{"id": model.ID})
@@ -92,11 +86,11 @@ func (s *Server) serve(c *gin.Context, appName, path string) {
 		return
 	}
 
+	err = doCall(call)
 	err = s.Agent.Submit(call)
 	if err != nil {
 		// NOTE if they cancel the request then it will stop the call (kind of cool),
 		// we could filter that error out here too as right now it yells a little
-
 		if err == context.DeadlineExceeded {
 			// TODO maneuver
 			// add this, since it means that start may not have been called [and it's relevant]

api/server/runner_listeners.go

@@ -1,38 +0,0 @@
-package server
-
-import (
-	"context"
-	"github.com/fnproject/fn/api/models"
-)
-
-type RunnerListener interface {
-	// BeforeDispatch called before a function run
-	BeforeDispatch(ctx context.Context, route *models.Route) error
-	// AfterDispatch called after a function run
-	AfterDispatch(ctx context.Context, route *models.Route) error
-}
-
-// AddRunListeners adds a listener that will be fired before and after a function run.
-func (s *Server) AddRunnerListener(listener RunnerListener) {
-	s.runnerListeners = append(s.runnerListeners, listener)
-}
-
-func (s *Server) FireBeforeDispatch(ctx context.Context, route *models.Route) error {
-	for _, l := range s.runnerListeners {
-		err := l.BeforeDispatch(ctx, route)
-		if err != nil {
-			return err
-		}
-	}
-	return nil
-}
-
-func (s *Server) FireAfterDispatch(ctx context.Context, route *models.Route) error {
-	for _, l := range s.runnerListeners {
-		err := l.AfterDispatch(ctx, route)
-		if err != nil {
-			return err
-		}
-	}
-	return nil
-}

api/server/server.go

@@ -17,6 +17,7 @@ import (
 	"github.com/fnproject/fn/api/common"
 	"github.com/fnproject/fn/api/datastore"
 	"github.com/fnproject/fn/api/datastore/cache"
+	"github.com/fnproject/fn/api/extenders"
 	"github.com/fnproject/fn/api/id"
 	"github.com/fnproject/fn/api/logs"
 	"github.com/fnproject/fn/api/models"
@@ -47,9 +48,8 @@ type Server struct {
 	MQ        models.MessageQueue
 	LogDB     models.LogStore
 
-	appListeners    []AppListener
+	appListeners []extenders.AppListener
-	middlewares     []Middleware
+	middlewares  []Middleware
-	runnerListeners []RunnerListener
 }
 
 // NewFromEnv creates a new Functions server based on env vars.

docs/operating/extending.md

@@ -14,8 +14,8 @@ Listeners are the main way to extend Fn.
 
 The following listener types are supported:
 
-* App Listeners - [GoDoc](https://godoc.org/github.com/fnproject/functions/api/server#AppListener)
+* App Listeners - [GoDoc](https://godoc.org/github.com/fnproject/fn/api/server#AppListener)
-* Runner Listeners - [GoDoc](https://godoc.org/github.com/fnproject/functions/api/server#RunnerListener)
+* Call Listeners - [GoDoc](https://godoc.org/github.com/fnproject/fn/api/server#CallListener)
 
 ### Creating a Listener