swarm: integrate OpenTracing; propagate ctx to internal APIs (#17169)

* swarm: propagate ctx, enable opentracing

* swarm/tracing: log error when tracing is misconfigured

vendor/github.com/uber/jaeger-client-go/config/options.go

@@ -0,0 +1,148 @@
+// Copyright (c) 2017 Uber Technologies, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package config
+
+import (
+	opentracing "github.com/opentracing/opentracing-go"
+	"github.com/uber/jaeger-lib/metrics"
+
+	"github.com/uber/jaeger-client-go"
+)
+
+// Option is a function that sets some option on the client.
+type Option func(c *Options)
+
+// Options control behavior of the client.
+type Options struct {
+	metrics             metrics.Factory
+	logger              jaeger.Logger
+	reporter            jaeger.Reporter
+	sampler             jaeger.Sampler
+	contribObservers    []jaeger.ContribObserver
+	observers           []jaeger.Observer
+	gen128Bit           bool
+	zipkinSharedRPCSpan bool
+	maxTagValueLength   int
+	tags                []opentracing.Tag
+	injectors           map[interface{}]jaeger.Injector
+	extractors          map[interface{}]jaeger.Extractor
+}
+
+// Metrics creates an Option that initializes Metrics in the tracer,
+// which is used to emit statistics about spans.
+func Metrics(factory metrics.Factory) Option {
+	return func(c *Options) {
+		c.metrics = factory
+	}
+}
+
+// Logger can be provided to log Reporter errors, as well as to log spans
+// if Reporter.LogSpans is set to true.
+func Logger(logger jaeger.Logger) Option {
+	return func(c *Options) {
+		c.logger = logger
+	}
+}
+
+// Reporter can be provided explicitly to override the configuration.
+// Useful for testing, e.g. by passing InMemoryReporter.
+func Reporter(reporter jaeger.Reporter) Option {
+	return func(c *Options) {
+		c.reporter = reporter
+	}
+}
+
+// Sampler can be provided explicitly to override the configuration.
+func Sampler(sampler jaeger.Sampler) Option {
+	return func(c *Options) {
+		c.sampler = sampler
+	}
+}
+
+// Observer can be registered with the Tracer to receive notifications about new Spans.
+func Observer(observer jaeger.Observer) Option {
+	return func(c *Options) {
+		c.observers = append(c.observers, observer)
+	}
+}
+
+// ContribObserver can be registered with the Tracer to recieve notifications
+// about new spans.
+func ContribObserver(observer jaeger.ContribObserver) Option {
+	return func(c *Options) {
+		c.contribObservers = append(c.contribObservers, observer)
+	}
+}
+
+// Gen128Bit specifies whether to generate 128bit trace IDs.
+func Gen128Bit(gen128Bit bool) Option {
+	return func(c *Options) {
+		c.gen128Bit = gen128Bit
+	}
+}
+
+// ZipkinSharedRPCSpan creates an option that enables sharing span ID between client
+// and server spans a la zipkin. If false, client and server spans will be assigned
+// different IDs.
+func ZipkinSharedRPCSpan(zipkinSharedRPCSpan bool) Option {
+	return func(c *Options) {
+		c.zipkinSharedRPCSpan = zipkinSharedRPCSpan
+	}
+}
+
+// MaxTagValueLength can be provided to override the default max tag value length.
+func MaxTagValueLength(maxTagValueLength int) Option {
+	return func(c *Options) {
+		c.maxTagValueLength = maxTagValueLength
+	}
+}
+
+// Tag creates an option that adds a tracer-level tag.
+func Tag(key string, value interface{}) Option {
+	return func(c *Options) {
+		c.tags = append(c.tags, opentracing.Tag{Key: key, Value: value})
+	}
+}
+
+// Injector registers an Injector with the given format.
+func Injector(format interface{}, injector jaeger.Injector) Option {
+	return func(c *Options) {
+		c.injectors[format] = injector
+	}
+}
+
+// Extractor registers an Extractor with the given format.
+func Extractor(format interface{}, extractor jaeger.Extractor) Option {
+	return func(c *Options) {
+		c.extractors[format] = extractor
+	}
+}
+
+func applyOptions(options ...Option) Options {
+	opts := Options{
+		injectors:  make(map[interface{}]jaeger.Injector),
+		extractors: make(map[interface{}]jaeger.Extractor),
+	}
+	for _, option := range options {
+		option(&opts)
+	}
+	if opts.metrics == nil {
+		opts.metrics = metrics.NullFactory
+	}
+	if opts.logger == nil {
+		opts.logger = jaeger.NullLogger
+	}
+	return opts
+}