func unbindServiceInstance(w http.ResponseWriter, r *http.Request, t auth.Token) error {
	instanceName, appName, serviceName := r.URL.Query().Get(":instance"), r.URL.Query().Get(":app"),
		r.URL.Query().Get(":service")
	noRestart, _ := strconv.ParseBool(InputValue(r, "noRestart"))
	force, _ := strconv.ParseBool(InputValue(r, "force"))
	instance, a, err := getServiceInstance(serviceName, instanceName, appName)
	if err != nil {
		return err
	}
	allowed := permission.Check(t, permission.PermServiceInstanceUpdateUnbind,
		append(permission.Contexts(permTypes.CtxTeam, instance.Teams),
			permission.Context(permTypes.CtxServiceInstance, instance.Name),
		)...,
	)
	if !allowed {
		return permission.ErrUnauthorized
	}
	allowed = permission.Check(t, permission.PermAppUpdateUnbind,
		contextsForApp(a)...,
	)
	if !allowed {
		return permission.ErrUnauthorized
	}
	if force {
		s, errGet := service.Get(instance.ServiceName)
		if errGet != nil {
			return errGet
		}
		allowed = permission.Check(t, permission.PermServiceUpdate,
			contextsForServiceProvision(&s)...,
		)
		if !allowed {
			return permission.ErrUnauthorized
		}
	}
	evt, err := event.New(&event.Opts{
		Target:     appTarget(appName),
		Kind:       permission.PermAppUpdateUnbind,
		Owner:      t,
		CustomData: event.FormToCustomData(InputFields(r)),
		Allowed:    event.Allowed(permission.PermAppReadEvents, contextsForApp(a)...),
	})
	if err != nil {
		return err
	}
	defer func() { evt.Done(err) }()
	w.Header().Set("Content-Type", "application/x-json-stream")
	keepAliveWriter := tsuruIo.NewKeepAliveWriter(w, 30*time.Second, "")
	defer keepAliveWriter.Stop()
	writer := &tsuruIo.SimpleJsonMessageEncoderWriter{Encoder: json.NewEncoder(keepAliveWriter)}
	evt.SetLogWriter(writer)
	err = instance.UnbindApp(service.UnbindAppArgs{
		App:         a,
		Restart:     !noRestart,
		ForceRemove: force,
		Event:       evt,
		RequestID:   requestIDHeader(r),
	})
	if err != nil {
		return err
	}
	fmt.Fprintf(evt, "\nInstance %q is not bound to the app %q anymore.\n", instanceName, appName)
	return nil
}
func unbindServiceInstance(w http.ResponseWriter, r *http.Request, t auth.Token) error {
	instanceName, appName, serviceName := r.URL.Query().Get(":instance"), r.URL.Query().Get(":app"),
		r.URL.Query().Get(":service")
	noRestart, _ := strconv.ParseBool(InputValue(r, "noRestart"))
	force, _ := strconv.ParseBool(InputValue(r, "force"))
	instance, a, err := getServiceInstance(serviceName, instanceName, appName)
	if err != nil {
		return err
	}
	allowed := permission.Check(t, permission.PermServiceInstanceUpdateUnbind,
		append(permission.Contexts(permTypes.CtxTeam, instance.Teams),
			permission.Context(permTypes.CtxServiceInstance, instance.Name),
		)...,
	)
	if !allowed {
		return permission.ErrUnauthorized
	}
	allowed = permission.Check(t, permission.PermAppUpdateUnbind,
		contextsForApp(a)...,
	)
	if !allowed {
		return permission.ErrUnauthorized
	}
	if force {
		s, errGet := service.Get(instance.ServiceName)
		if errGet != nil {
			return errGet
		}
		allowed = permission.Check(t, permission.PermServiceUpdate,
			contextsForServiceProvision(&s)...,
		)
		if !allowed {
			return permission.ErrUnauthorized
		}
	}
	evt, err := event.New(&event.Opts{
		Target:     appTarget(appName),
		Kind:       permission.PermAppUpdateUnbind,
		Owner:      t,
		CustomData: event.FormToCustomData(InputFields(r)),
		Allowed:    event.Allowed(permission.PermAppReadEvents, contextsForApp(a)...),
	})
	if err != nil {
		return err
	}
	defer func() { evt.Done(err) }()
	w.Header().Set("Content-Type", "application/x-json-stream")
	keepAliveWriter := tsuruIo.NewKeepAliveWriter(w, 30*time.Second, "")
	defer keepAliveWriter.Stop()
	writer := &tsuruIo.SimpleJsonMessageEncoderWriter{Encoder: json.NewEncoder(keepAliveWriter)}
	evt.SetLogWriter(writer)
	err = instance.UnbindApp(service.UnbindAppArgs{
		App:         a,
		Restart:     !noRestart,
		ForceRemove: force,
		Event:       evt,
		RequestID:   requestIDHeader(r),
	})
	if err != nil {
		return err
	}
	fmt.Fprintf(evt, "\nInstance %q is not bound to the app %q anymore.\n", instanceName, appName)
	return nil
}
// title: unbind service instance
// path: /services/{service}/instances/{instance}/{app}
// method: DELETE
// produce: application/x-json-stream
// responses:
//   200: Ok
//   400: Invalid data
//   401: Unauthorized
//   404: App not found