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server.go
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server.go
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// +kubebuilder:validation:Optional
package http
import (
"context"
"crypto/tls"
"fmt"
"net/http"
"time"
"github.com/gorilla/mux"
"github.com/prometheus/client_golang/prometheus"
"go.uber.org/fx"
"github.com/fluxninja/aperture/v2/pkg/config"
"github.com/fluxninja/aperture/v2/pkg/log"
"github.com/fluxninja/aperture/v2/pkg/metrics"
"github.com/fluxninja/aperture/v2/pkg/net/listener"
panichandler "github.com/fluxninja/aperture/v2/pkg/panic-handler"
"github.com/fluxninja/aperture/v2/pkg/utils"
)
const (
defaultServerKey = "server.http"
defaultHandlerName = "default"
)
type monitoringContext struct {
context.Context
handlerName string
}
// ServerModule is an fx module that provides annotated HTTP Server using the default listener and registers its metrics with the prometheus registry.
func ServerModule() fx.Option {
return fx.Options(
ServerConstructor{}.Annotate(),
)
}
// HTTPServerConfig holds configuration for HTTP Server.
// swagger:model
// +kubebuilder:object:generate=true
type HTTPServerConfig struct {
// Idle timeout
IdleTimeout config.Duration `json:"idle_timeout" validate:"gte=0s" default:"30s"`
// Read header timeout
ReadHeaderTimeout config.Duration `json:"read_header_timeout" validate:"gte=0s" default:"10s"`
// Read timeout
ReadTimeout config.Duration `json:"read_timeout" validate:"gte=0s" default:"10s"`
// Write timeout
WriteTimeout config.Duration `json:"write_timeout" validate:"gte=0s" default:"45s"`
// Max header size in bytes
MaxHeaderBytes int `json:"max_header_bytes" validate:"gte=0" default:"1048576"`
// Buckets specification in latency histogram
LatencyBucketsMS []float64 `json:"latency_buckets_ms" validate:"gte=0" default:"[10.0,25.0,100.0,250.0,1000.0]"`
// Disable HTTP Keepalive
DisableHTTPKeepAlives bool `json:"disable_http_keep_alives" default:"false"`
}
// ServerConstructor holds fields to create an annotated HTTP Server.
type ServerConstructor struct {
// Name of http server instance -- empty for main server
Name string
// Name of listener instance
ListenerName string
// Name of tls config instance
TLSConfigName string
// Viper config key/server name
ConfigKey string
// Default Server Config
DefaultConfig HTTPServerConfig
}
// Annotate creates an annotated instance of HTTP Server.
func (constructor ServerConstructor) Annotate() fx.Option {
if constructor.ConfigKey == "" {
constructor.ConfigKey = defaultServerKey
}
tlsName := config.NameTag(constructor.TLSConfigName) + ` optional:"true"`
name := config.NameTag(constructor.Name)
return fx.Options(
fx.Provide(
fx.Annotate(
constructor.provideServer,
fx.ParamTags(config.NameTag(constructor.ListenerName), tlsName),
fx.ResultTags(name, name, name),
),
),
)
}
// Server holds fields for custom HTTP server.
type Server struct {
Server *http.Server
Mux *mux.Router
Listener *listener.Listener
TLSConfig *tls.Config
// As we are using Gorilla Mux, root handler is registered the last as a catch all
RootHandler http.Handler
RequestCounters *prometheus.CounterVec
ErrorCounters *prometheus.CounterVec
Latencies *prometheus.HistogramVec
}
func (constructor ServerConstructor) provideServer(
listener *listener.Listener,
tlsConfig *tls.Config,
unmarshaller config.Unmarshaller,
lifecycle fx.Lifecycle,
shutdowner fx.Shutdowner,
pr *prometheus.Registry,
) (*mux.Router, *http.Server, *Server, error) {
config := constructor.DefaultConfig
if err := unmarshaller.UnmarshalKey(constructor.ConfigKey, &config); err != nil {
log.Error().Err(err).Msg("Unable to deserialize httpserver configuration!")
return nil, nil, nil, err
}
// Register metrics
defaultLabels := []string{metrics.MethodLabel, metrics.StatusCodeLabel, metrics.HandlerName}
errorCounters := prometheus.NewCounterVec(prometheus.CounterOpts{
Name: metrics.HTTPErrorMetricName,
Help: "The total number of errors that occurred",
}, defaultLabels)
requestCounters := prometheus.NewCounterVec(prometheus.CounterOpts{
Name: metrics.HTTPRequestMetricName,
Help: "The total number of requests that occurred",
}, defaultLabels)
// We record latency milliseconds
latencyHistograms := prometheus.NewHistogramVec(prometheus.HistogramOpts{
Name: metrics.HTTPRequestLatencyMetricName,
Help: "Latency of the requests processed by the server",
Buckets: config.LatencyBucketsMS,
}, defaultLabels)
for _, metric := range []prometheus.Collector{errorCounters, requestCounters, latencyHistograms} {
err := pr.Register(metric)
if err != nil {
// Ignore already registered error, as this is not harmful. Metrics may
// be registered by other running server.
if _, ok := err.(prometheus.AlreadyRegisteredError); !ok {
return nil, nil, nil, fmt.Errorf("could not register prometheus metrics: %w", err)
}
}
}
router := mux.NewRouter()
server := &http.Server{
Handler: router,
MaxHeaderBytes: config.MaxHeaderBytes,
IdleTimeout: config.IdleTimeout.AsDuration(),
ReadHeaderTimeout: config.ReadHeaderTimeout.AsDuration(),
ReadTimeout: config.ReadTimeout.AsDuration(),
WriteTimeout: config.WriteTimeout.AsDuration(),
TLSConfig: tlsConfig,
}
httpServer := &Server{
Server: server,
Mux: router,
Listener: listener,
TLSConfig: tlsConfig,
RequestCounters: requestCounters,
ErrorCounters: errorCounters,
Latencies: latencyHistograms,
}
router.Use(httpServer.monitoringMiddleware)
lifecycle.Append(fx.Hook{
OnStart: func(_ context.Context) error {
panichandler.Go(func() {
// request shutdown if this server exits
defer func() {
utils.Shutdown(shutdowner)
}()
listener := listener.GetListener()
if tlsConfig != nil {
listener = tls.NewListener(listener, tlsConfig)
}
log.Info().Str("constructor", constructor.ConfigKey).Str("addr", listener.Addr().String()).Msg("Starting HTTP server")
// check if RootHandler is set
if httpServer.RootHandler != nil {
log.Info().Msg("Registering RootHandlerFunc!")
router.PathPrefix("/").Handler(httpServer.RootHandler)
}
if err := server.Serve(listener); err != http.ErrServerClosed {
log.Error().Err(err).Msg("Unable to start HTTP server!")
}
})
return nil
},
OnStop: func(ctx context.Context) error {
listener := listener.GetListener()
log.Info().Str("constructor", constructor.ConfigKey).Str("addr", listener.Addr().String()).Msg("Stopping HTTP server")
return server.Shutdown(ctx)
},
})
return router, server, httpServer, nil
}
func (s *Server) monitoringMiddleware(next http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
ctx := &monitoringContext{}
ctx.Context = r.Context()
ctx.handlerName = defaultHandlerName
startTime := time.Now()
rec := newStatusRecorder(w)
// Call the next handler, which can be another middleware in the chain, or the final handler.
next.ServeHTTP(rec, r.WithContext(ctx))
duration := time.Since(startTime)
labels := map[string]string{
metrics.MethodLabel: r.Method,
metrics.StatusCodeLabel: fmt.Sprintf("%d", rec.statusCode),
metrics.HandlerName: ctx.handlerName,
}
requestCounter, err := s.RequestCounters.GetMetricWith(labels)
if err != nil {
log.Debug().Msgf("Could not extract request counter metric from registry: %v", err)
} else {
requestCounter.Inc()
}
errorCounter, err := s.ErrorCounters.GetMetricWith(labels)
if err != nil {
log.Debug().Msgf("Could not extract error counter metric from registry: %v", err)
} else if rec.statusCode >= http.StatusBadRequest {
errorCounter.Inc()
}
latencyHistogram, err := s.Latencies.GetMetricWith(labels)
if err != nil {
log.Debug().Msgf("Could not extract latency histogram metric from registry: %v", err)
} else {
latencyHistogram.Observe(float64(duration.Milliseconds()))
}
})
}
// HandlerNameMiddleware sets handler name in monitoring context.
func HandlerNameMiddleware(handlerName string) func(http.Handler) http.Handler {
return func(next http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
ctx := r.Context()
if mCtx, ok := ctx.(*monitoringContext); ok {
mCtx.handlerName = handlerName
}
next.ServeHTTP(w, r.WithContext(ctx))
})
}
}
func newStatusRecorder(w http.ResponseWriter) *statusRecorder {
return &statusRecorder{ResponseWriter: w}
}
type statusRecorder struct {
http.ResponseWriter
statusCode int
}
// WriteHeader records statusCode and calls wrapped WriteHeader method.
func (sr *statusRecorder) WriteHeader(statusCode int) {
sr.statusCode = statusCode
sr.ResponseWriter.WriteHeader(statusCode)
}