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fx-driver.go
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fx-driver.go
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package notifiers
import (
"context"
"errors"
"github.com/prometheus/client_golang/prometheus"
"go.uber.org/fx"
"google.golang.org/protobuf/types/known/wrapperspb"
"github.com/fluxninja/aperture/v2/pkg/config"
"github.com/fluxninja/aperture/v2/pkg/status"
)
// FxOptionsFunc is a function that returns fx.Option.
type FxOptionsFunc func(Key, config.Unmarshaller, status.Registry) (fx.Option, error)
type fxRunner struct {
statusRegistry status.Registry
fxRunnerStatusRegistry status.Registry
app *fx.App
prometheusRegistry *prometheus.Registry
*unmarshalKeyNotifier
fxOptionsFuncs []FxOptionsFunc
}
// Make sure fxRunner implements KeyNotifier.
var _ KeyNotifier = (*fxRunner)(nil)
func (fr *fxRunner) processEvent(event Event, unmarshaller config.Unmarshaller) {
logger := fr.fxRunnerStatusRegistry.GetLogger()
switch event.Type {
case Write:
logger.Info().Str("event", event.String()).Msg("key update")
if fr.app != nil {
// stop existing app
err := fr.deinitApp()
if err != nil {
logger.Error().Err(err).Msg("Failed to stop existing app")
}
}
// instantiate and start a new app
err := fr.initApp(event.Key, unmarshaller)
if err != nil {
logger.Error().Err(err).Msg("Failed to instantiate and start a new app")
}
case Remove:
logger.Info().Str("event", event.String()).Msg("key removed")
// deinit the app
err := fr.deinitApp()
if err != nil {
logger.Error().Err(err).Msg("Failed to deinit app")
}
fr.statusRegistry.Detach()
}
}
func (fr *fxRunner) initApp(key Key, unmarshaller config.Unmarshaller) error {
fr.fxRunnerStatusRegistry.SetStatus(status.NewStatus(wrapperspb.String("policy runner initializing"), nil))
logger := fr.fxRunnerStatusRegistry.GetLogger()
if fr.app == nil && unmarshaller != nil {
var options []fx.Option
for _, fxOptionsFunc := range fr.fxOptionsFuncs {
o, e := fxOptionsFunc(key, unmarshaller, fr.statusRegistry)
if e != nil {
logger.Error().Err(e).Msg("fxOptionsFunc failed")
return e
}
options = append(options, o)
}
option := fx.Options(options...)
fr.app = fx.New(
// Note: Supplying unmarshaller directly results in supplying
// concrete type instead of interface, thus supplying via Provide.
fx.Provide(func() config.Unmarshaller { return unmarshaller }),
// Supply keyinfo
fx.Supply(key),
// Supply status registry for the key
fx.Supply(fr.statusRegistry),
// Supply prometheus registry
fx.Supply(fr.prometheusRegistry),
option,
)
var err error
if err = fr.app.Err(); err != nil {
visualize, _ := fx.VisualizeError(err)
logger.Error().Err(err).Str("visualize", visualize).Msg("fx.New failed")
fr.fxRunnerStatusRegistry.SetStatus(status.NewStatus(nil, err))
_ = fr.deinitApp()
return err
}
fr.fxRunnerStatusRegistry.SetStatus(status.NewStatus(wrapperspb.String("policy runner starting"), nil))
ctx, cancel := context.WithTimeout(context.Background(), fr.app.StartTimeout())
defer cancel()
if err = fr.app.Start(ctx); err != nil {
logger.Error().Err(err).Msg("Could not start application")
fr.fxRunnerStatusRegistry.SetStatus(status.NewStatus(nil, err))
return err
}
fr.fxRunnerStatusRegistry.SetStatus(status.NewStatus(wrapperspb.String("policy runner started"), nil))
} else {
fr.fxRunnerStatusRegistry.SetStatus(status.NewStatus(nil, errors.New("fxRunner is not initialized")))
}
return nil
}
func (fr *fxRunner) deinitApp() error {
fr.fxRunnerStatusRegistry.SetStatus(status.NewStatus(wrapperspb.String("policy runner stopping"), nil))
logger := fr.fxRunnerStatusRegistry.GetLogger()
if fr.app != nil {
ctx, cancel := context.WithTimeout(context.Background(), fr.app.StopTimeout())
defer func() { fr.app = nil }()
defer cancel()
if err := fr.app.Stop(ctx); err != nil {
logger.Error().Err(err).Msg("Could not stop application")
return err
}
}
fr.fxRunnerStatusRegistry.SetStatus(status.NewStatus(wrapperspb.String("policy runner stopped"), nil))
return nil
}
// fxDriver tracks prefix and allows spawning "mini FX-based apps" per key in the prefix.
type fxDriver struct {
statusRegistry status.Registry
prometheusRegistry *prometheus.Registry
// Options for new unmarshaller instances
*unmarshalPrefixNotifier
// function to provide fx.Options.
//
// Resulting fx.Options will be used to create a "mini FX-based apps" per key.
// The lifecycle of the app will be tied to the existence of the key.
// Note that when key's contents change the previous App will be stopped
// and a fresh one will be created.
fxOptionsFuncs []FxOptionsFunc
}
// Make sure FxDriver implements PrefixNotifier.
var _ PrefixNotifier = (*fxDriver)(nil)
// NewFxDriver creates a new FxDriver.
func NewFxDriver(
statusRegistry status.Registry,
prometheusRegistry *prometheus.Registry,
getUnmarshallerFunc GetUnmarshallerFunc,
fxOptionsFuncs []FxOptionsFunc,
) (*fxDriver, error) {
// Subscribe to all prefixes and additional notifier callback is nil
upn, err := NewUnmarshalPrefixNotifier("", nil, getUnmarshallerFunc)
if err != nil {
return nil, err
}
return &fxDriver{
statusRegistry: statusRegistry,
prometheusRegistry: prometheusRegistry,
unmarshalPrefixNotifier: upn,
fxOptionsFuncs: fxOptionsFuncs,
}, nil
}
// GetKeyNotifier returns a KeyNotifier that will notify the driver of key changes.
func (fxd *fxDriver) GetKeyNotifier(key Key) (KeyNotifier, error) {
unmarshaller, err := fxd.getUnmarshallerFunc(nil)
if err != nil {
return nil, err
}
statusRegistry := fxd.statusRegistry.Child("key", key.String())
fr := &fxRunner{
fxOptionsFuncs: fxd.fxOptionsFuncs,
statusRegistry: statusRegistry,
fxRunnerStatusRegistry: statusRegistry.Child("system", "fx_runner"),
prometheusRegistry: fxd.prometheusRegistry,
}
ukn, err := NewUnmarshalKeyNotifier(key, unmarshaller, fr.processEvent)
if err != nil {
return nil, err
}
fr.unmarshalKeyNotifier = ukn
return fr, nil
}