/
connect_service.go
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/
connect_service.go
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//nolint:dupl
package service
import (
"context"
"errors"
"fmt"
"net"
"net/http"
"strings"
"sync"
"time"
evaluationV1 "buf.build/gen/go/open-feature/flagd/connectrpc/go/flagd/evaluation/v1/evaluationv1connect"
schemaConnectV1 "buf.build/gen/go/open-feature/flagd/connectrpc/go/schema/v1/schemav1connect"
"github.com/open-feature/flagd/core/pkg/evaluator"
"github.com/open-feature/flagd/core/pkg/logger"
"github.com/open-feature/flagd/core/pkg/service"
"github.com/open-feature/flagd/core/pkg/telemetry"
"github.com/open-feature/flagd/flagd/pkg/service/middleware"
corsmw "github.com/open-feature/flagd/flagd/pkg/service/middleware/cors"
h2cmw "github.com/open-feature/flagd/flagd/pkg/service/middleware/h2c"
metricsmw "github.com/open-feature/flagd/flagd/pkg/service/middleware/metrics"
"github.com/prometheus/client_golang/prometheus/promhttp"
"go.uber.org/zap"
"golang.org/x/net/http2"
"golang.org/x/net/http2/h2c"
"golang.org/x/sync/errgroup"
"google.golang.org/grpc"
"google.golang.org/grpc/health"
"google.golang.org/grpc/health/grpc_health_v1"
"google.golang.org/protobuf/encoding/protojson"
)
const (
ErrorPrefix = "FlagdError:"
flagdSchemaPrefix = "/flagd"
)
// bufSwitchHandler combines the handlers of the old and new evaluation schema and combines them into one
// this way we support both the new and the (deprecated) old schemas until only the new schema is supported
// NOTE: this will not be required anymore when it is time to work on https://github.com/open-feature/flagd/issues/1088
type bufSwitchHandler struct {
old http.Handler
new http.Handler
}
func (b bufSwitchHandler) ServeHTTP(writer http.ResponseWriter, request *http.Request) {
if strings.HasPrefix(request.URL.Path, flagdSchemaPrefix) {
b.new.ServeHTTP(writer, request)
} else {
b.old.ServeHTTP(writer, request)
}
}
type ConnectService struct {
logger *logger.Logger
eval evaluator.IEvaluator
metrics *telemetry.MetricsRecorder
eventingConfiguration *eventingConfiguration
server *http.Server
metricsServer *http.Server
serverMtx sync.RWMutex
metricsServerMtx sync.RWMutex
readinessEnabled bool
}
// NewConnectService creates a ConnectService with provided parameters
func NewConnectService(
logger *logger.Logger, evaluator evaluator.IEvaluator, mRecorder *telemetry.MetricsRecorder,
) *ConnectService {
return &ConnectService{
logger: logger,
eval: evaluator,
metrics: mRecorder,
eventingConfiguration: &eventingConfiguration{
subs: make(map[interface{}]chan service.Notification),
mu: &sync.RWMutex{},
},
}
}
// Serve serves services with provided configuration options
func (s *ConnectService) Serve(ctx context.Context, svcConf service.Configuration) error {
g, gCtx := errgroup.WithContext(ctx)
s.readinessEnabled = true
g.Go(func() error {
return s.startServer(svcConf)
})
g.Go(func() error {
return s.startMetricsServer(svcConf)
})
g.Go(func() error {
<-gCtx.Done()
s.serverMtx.RLock()
defer s.serverMtx.RUnlock()
if s.server != nil {
if err := s.server.Shutdown(gCtx); err != nil {
return fmt.Errorf("error returned from flag evaluation server shutdown: %w", err)
}
}
return nil
})
g.Go(func() error {
<-gCtx.Done()
s.metricsServerMtx.RLock()
defer s.metricsServerMtx.RUnlock()
if s.metricsServer != nil {
if err := s.metricsServer.Shutdown(gCtx); err != nil {
return fmt.Errorf("error returned from metrics server shutdown: %w", err)
}
}
return nil
})
if err := g.Wait(); err != nil {
return fmt.Errorf("errgroup closed with error: %w", err)
}
return nil
}
// Notify emits change event notifications for subscriptions
func (s *ConnectService) Notify(n service.Notification) {
s.eventingConfiguration.emitToAll(n)
}
// nolint: funlen
func (s *ConnectService) setupServer(svcConf service.Configuration) (net.Listener, error) {
var lis net.Listener
var err error
if svcConf.SocketPath != "" {
lis, err = net.Listen("unix", svcConf.SocketPath)
} else {
address := fmt.Sprintf(":%d", svcConf.Port)
lis, err = net.Listen("tcp", address)
}
if err != nil {
return nil, fmt.Errorf("error creating listener for flag evaluation service: %w", err)
}
// register handler for old flag evaluation schema
// can be removed as a part of https://github.com/open-feature/flagd/issues/1088
fes := NewOldFlagEvaluationService(
s.logger.WithFields(zap.String("component", "flagservice")),
s.eval,
s.eventingConfiguration,
s.metrics,
)
marshalOpts := WithJSON(
// json parsing configuration - we emit "unpopulated" fields (falsy fields are not dropped)
protojson.MarshalOptions{EmitUnpopulated: true},
protojson.UnmarshalOptions{DiscardUnknown: true},
)
_, oldHandler := schemaConnectV1.NewServiceHandler(fes, append(svcConf.Options, marshalOpts)...)
// register handler for new flag evaluation schema
newFes := NewFlagEvaluationService(s.logger.WithFields(zap.String("component", "flagd.evaluation.v1")),
s.eval,
s.eventingConfiguration,
s.metrics,
)
_, newHandler := evaluationV1.NewServiceHandler(newFes, append(svcConf.Options, marshalOpts)...)
bs := bufSwitchHandler{
old: oldHandler,
new: newHandler,
}
s.serverMtx.Lock()
s.server = &http.Server{
ReadHeaderTimeout: time.Second,
Handler: bs,
}
s.serverMtx.Unlock()
// Add middlewares
metricsMiddleware := metricsmw.NewHTTPMetric(metricsmw.Config{
Service: svcConf.ServiceName,
MetricRecorder: s.metrics,
Logger: s.logger,
HandlerID: "",
})
s.AddMiddleware(metricsMiddleware)
corsMiddleware := corsmw.New(svcConf.CORS)
s.AddMiddleware(corsMiddleware)
if svcConf.CertPath == "" || svcConf.KeyPath == "" {
h2cMiddleware := h2cmw.New()
s.AddMiddleware(h2cMiddleware)
}
return lis, nil
}
func (s *ConnectService) AddMiddleware(mw middleware.IMiddleware) {
s.server.Handler = mw.Handler(s.server.Handler)
}
func (s *ConnectService) Shutdown() {
s.readinessEnabled = false
s.eventingConfiguration.emitToAll(service.Notification{
Type: service.Shutdown,
Data: map[string]interface{}{},
})
}
func (s *ConnectService) startServer(svcConf service.Configuration) error {
lis, err := s.setupServer(svcConf)
if err != nil {
return err
}
s.logger.Info(fmt.Sprintf("Flag IResolver listening at %s", lis.Addr()))
if svcConf.CertPath != "" && svcConf.KeyPath != "" {
if err := s.server.ServeTLS(
lis,
svcConf.CertPath,
svcConf.KeyPath,
); err != nil && !errors.Is(err, http.ErrServerClosed) {
return fmt.Errorf("error returned from flag evaluation server: %w", err)
}
} else {
if err := s.server.Serve(
lis,
); err != nil && !errors.Is(err, http.ErrServerClosed) {
return fmt.Errorf("error returned from flag evaluation server: %w", err)
}
}
return nil
}
func (s *ConnectService) startMetricsServer(svcConf service.Configuration) error {
s.logger.Info(fmt.Sprintf("metrics and probes listening at %d", svcConf.ManagementPort))
grpc := grpc.NewServer()
grpc_health_v1.RegisterHealthServer(grpc, health.NewServer())
mux := http.NewServeMux()
mux.Handle("/healthz", http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
w.WriteHeader(http.StatusOK)
}))
mux.Handle("/readyz", http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
if s.readinessEnabled && svcConf.ReadinessProbe() {
w.WriteHeader(http.StatusOK)
} else {
w.WriteHeader(http.StatusPreconditionFailed)
}
}))
mux.Handle("/metrics", promhttp.Handler())
handler := http.HandlerFunc(func(writer http.ResponseWriter, request *http.Request) {
// if this is 'application/grpc' and HTTP2, handle with gRPC, otherwise HTTP.
if request.ProtoMajor == 2 && strings.HasPrefix(request.Header.Get("Content-Type"), "application/grpc") {
grpc.ServeHTTP(writer, request)
} else {
mux.ServeHTTP(writer, request)
return
}
})
s.metricsServerMtx.Lock()
s.metricsServer = &http.Server{
Addr: fmt.Sprintf(":%d", svcConf.ManagementPort),
ReadHeaderTimeout: 3 * time.Second,
Handler: h2c.NewHandler(handler, &http2.Server{}), // we need to use h2c to support plaintext HTTP2
}
s.metricsServerMtx.Unlock()
if err := s.metricsServer.ListenAndServe(); err != nil && !errors.Is(err, http.ErrServerClosed) {
return fmt.Errorf("error returned from metrics server: %w", err)
}
return nil
}