traefik/pkg/server/middleware/chainbuilder.go

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package middleware
import (
"context"
"github.com/containous/alice"
"github.com/containous/traefik/v2/pkg/config/static"
"github.com/containous/traefik/v2/pkg/log"
"github.com/containous/traefik/v2/pkg/metrics"
"github.com/containous/traefik/v2/pkg/middlewares/accesslog"
metricsmiddleware "github.com/containous/traefik/v2/pkg/middlewares/metrics"
"github.com/containous/traefik/v2/pkg/middlewares/requestdecorator"
mTracing "github.com/containous/traefik/v2/pkg/middlewares/tracing"
"github.com/containous/traefik/v2/pkg/tracing"
"github.com/containous/traefik/v2/pkg/tracing/jaeger"
)
// ChainBuilder Creates a middleware chain by entry point. It is used for middlewares that are created almost systematically and that need to be created before all others.
type ChainBuilder struct {
metricsRegistry metrics.Registry
accessLoggerMiddleware *accesslog.Handler
tracer *tracing.Tracing
requestDecorator *requestdecorator.RequestDecorator
}
// NewChainBuilder Creates a new ChainBuilder.
func NewChainBuilder(staticConfiguration static.Configuration, metricsRegistry metrics.Registry, accessLoggerMiddleware *accesslog.Handler) *ChainBuilder {
return &ChainBuilder{
metricsRegistry: metricsRegistry,
accessLoggerMiddleware: accessLoggerMiddleware,
tracer: setupTracing(staticConfiguration.Tracing),
requestDecorator: requestdecorator.New(staticConfiguration.HostResolver),
}
}
// Build a middleware chain by entry point.
func (c *ChainBuilder) Build(ctx context.Context, entryPointName string) alice.Chain {
chain := alice.New()
if c.accessLoggerMiddleware != nil {
chain = chain.Append(accesslog.WrapHandler(c.accessLoggerMiddleware))
}
if c.tracer != nil {
chain = chain.Append(mTracing.WrapEntryPointHandler(ctx, c.tracer, entryPointName))
}
if c.metricsRegistry != nil && c.metricsRegistry.IsEpEnabled() {
chain = chain.Append(metricsmiddleware.WrapEntryPointHandler(ctx, c.metricsRegistry, entryPointName))
}
return chain.Append(requestdecorator.WrapHandler(c.requestDecorator))
}
// Close accessLogger and tracer.
func (c *ChainBuilder) Close() {
if c.accessLoggerMiddleware != nil {
if err := c.accessLoggerMiddleware.Close(); err != nil {
log.WithoutContext().Errorf("Could not close the access log file: %s", err)
}
}
if c.tracer != nil {
c.tracer.Close()
}
}
func setupTracing(conf *static.Tracing) *tracing.Tracing {
if conf == nil {
return nil
}
var backend tracing.Backend
if conf.Jaeger != nil {
backend = conf.Jaeger
}
if conf.Zipkin != nil {
if backend != nil {
log.WithoutContext().Error("Multiple tracing backend are not supported: cannot create Zipkin backend.")
} else {
backend = conf.Zipkin
}
}
if conf.Datadog != nil {
if backend != nil {
log.WithoutContext().Error("Multiple tracing backend are not supported: cannot create Datadog backend.")
} else {
backend = conf.Datadog
}
}
if conf.Instana != nil {
if backend != nil {
log.WithoutContext().Error("Multiple tracing backend are not supported: cannot create Instana backend.")
} else {
backend = conf.Instana
}
}
if conf.Haystack != nil {
if backend != nil {
log.WithoutContext().Error("Multiple tracing backend are not supported: cannot create Haystack backend.")
} else {
backend = conf.Haystack
}
}
if backend == nil {
log.WithoutContext().Debug("Could not initialize tracing, using Jaeger by default")
defaultBackend := &jaeger.Config{}
defaultBackend.SetDefaults()
backend = defaultBackend
}
tracer, err := tracing.NewTracing(conf.ServiceName, conf.SpanNameLimit, backend)
if err != nil {
log.WithoutContext().Warnf("Unable to create tracer: %v", err)
return nil
}
return tracer
}