pkg/log/utils.go - voltha-lib-go - Gitiles

 /*
  * Copyright 2018-present Open Networking Foundation

  * 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.
  */

 // File contains utility functions to support Open Tracing in conjunction with
 // Enhanced Logging based on context propagation

 package log

 import (
 	"context"
 	"errors"
 	"fmt"
 	"github.com/opentracing/opentracing-go"
 	jtracing "github.com/uber/jaeger-client-go"
 	jcfg "github.com/uber/jaeger-client-go/config"
 	"io"
 	"os"
 	"strings"
 	"sync"
 )

 const (
 	RootSpanNameKey = "op-name"
 )

 // Global Settings governing the Log Correlation and Tracing features. Should only
 // be updated through the exposed public methods
 type LogFeaturesManager struct {
 	isTracePublishingEnabled bool
 	isLogCorrelationEnabled  bool
 	componentName            string // Name of component extracted from ENV variable
 	activeTraceAgentAddress  string
 	lock                     sync.Mutex
 }

 var globalLFM *LogFeaturesManager = &LogFeaturesManager{}

 func GetGlobalLFM() *LogFeaturesManager {
 	return globalLFM
 }

 // A Wrapper to utilize currently Active Tracer instance. The middleware library being used for generating
 // Spans for GRPC API calls does not support dynamically setting the Active Tracer similar to the SetGlobalTracer method
 // provided by OpenTracing API
 type ActiveTracerProxy struct {
 }

 func (atw ActiveTracerProxy) StartSpan(operationName string, opts ...opentracing.StartSpanOption) opentracing.Span {
 	return opentracing.GlobalTracer().StartSpan(operationName, opts...)
 }

 func (atw ActiveTracerProxy) Inject(sm opentracing.SpanContext, format interface{}, carrier interface{}) error {
 	return opentracing.GlobalTracer().Inject(sm, format, carrier)
 }

 func (atw ActiveTracerProxy) Extract(format interface{}, carrier interface{}) (opentracing.SpanContext, error) {
 	return opentracing.GlobalTracer().Extract(format, carrier)
 }

 // Jaeger complaint Logger instance to redirect logs to Default Logger
 type traceLogger struct {
 	logger *clogger
 }

 func (tl traceLogger) Error(msg string) {
 	tl.logger.Error(context.Background(), msg)
 }

 func (tl traceLogger) Infof(msg string, args ...interface{}) {
 	// Tracing logs should be performed only at Debug Verbosity
 	tl.logger.Debugf(context.Background(), msg, args...)
 }

 // Wrapper to handle correct Closer call at the time of Process Termination
 type traceCloser struct {
 }

 func (c traceCloser) Close() error {
 	currentActiveTracer := opentracing.GlobalTracer()
 	if currentActiveTracer != nil {
 		if jTracer, ok := currentActiveTracer.(*jtracing.Tracer); ok {
 			jTracer.Close()
 		}
 	}

 	return nil
 }

 // Method to Initialize Jaeger based Tracing client based on initial status of Tracing Publish and Log Correlation
 func (lfm *LogFeaturesManager) InitTracingAndLogCorrelation(tracePublishEnabled bool, traceAgentAddress string, logCorrelationEnabled bool) (io.Closer, error) {
 	lfm.componentName = os.Getenv("COMPONENT_NAME")
 	if lfm.componentName == "" {
 		return nil, errors.New("Unable to retrieve PoD Component Name from Runtime env")
 	}

 	lfm.lock.Lock()
 	defer lfm.lock.Unlock()

 	// Use NoopTracer when both Tracing Publishing and Log Correlation are disabled
 	if !tracePublishEnabled && !logCorrelationEnabled {
 		logger.Info(context.Background(), "Skipping Global Tracer initialization as both Trace publish and Log correlation are configured as disabled")
 		lfm.isTracePublishingEnabled = false
 		lfm.isLogCorrelationEnabled = false
 		opentracing.SetGlobalTracer(opentracing.NoopTracer{})
 		return traceCloser{}, nil
 	}

 	tracer, _, err := lfm.constructJaegerTracer(tracePublishEnabled, traceAgentAddress, true)
 	if err != nil {
 		return nil, err
 	}

 	// Initialize variables representing Active Status
 	opentracing.SetGlobalTracer(tracer)
 	lfm.isTracePublishingEnabled = tracePublishEnabled
 	lfm.activeTraceAgentAddress = traceAgentAddress
 	lfm.isLogCorrelationEnabled = logCorrelationEnabled
 	return traceCloser{}, nil
 }

 // Method to replace Active Tracer along with graceful closer of previous tracer
 func (lfm *LogFeaturesManager) replaceActiveTracer(tracer opentracing.Tracer) {
 	currentActiveTracer := opentracing.GlobalTracer()
 	opentracing.SetGlobalTracer(tracer)

 	if currentActiveTracer != nil {
 		if jTracer, ok := currentActiveTracer.(*jtracing.Tracer); ok {
 			jTracer.Close()
 		}
 	}
 }

 func (lfm *LogFeaturesManager) GetLogCorrelationStatus() bool {
 	lfm.lock.Lock()
 	defer lfm.lock.Unlock()

 	return lfm.isLogCorrelationEnabled
 }

 func (lfm *LogFeaturesManager) SetLogCorrelationStatus(isEnabled bool) {
 	lfm.lock.Lock()
 	defer lfm.lock.Unlock()

 	if isEnabled == lfm.isLogCorrelationEnabled {
 		logger.Debugf(context.Background(), "Ignoring Log Correlation Set operation with value %t; current Status same as desired", isEnabled)
 		return
 	}

 	if isEnabled {
 		// Construct new Tracer instance if Log Correlation has been enabled and current active tracer is a NoopTracer instance.
 		// Continue using the earlier tracer instance in case of any error
 		if _, ok := opentracing.GlobalTracer().(opentracing.NoopTracer); ok {
 			tracer, _, err := lfm.constructJaegerTracer(lfm.isTracePublishingEnabled, lfm.activeTraceAgentAddress, false)
 			if err != nil {
 				logger.Warnf(context.Background(), "Log Correlation Enable operation failed with error: %s", err.Error())
 				return
 			}

 			lfm.replaceActiveTracer(tracer)
 		}

 		lfm.isLogCorrelationEnabled = true
 		logger.Info(context.Background(), "Log Correlation has been enabled")

 	} else {
 		// Switch to NoopTracer when Log Correlation has been disabled and Tracing Publish is already disabled
 		if _, ok := opentracing.GlobalTracer().(opentracing.NoopTracer); !ok && !lfm.isTracePublishingEnabled {
 			lfm.replaceActiveTracer(opentracing.NoopTracer{})
 		}

 		lfm.isLogCorrelationEnabled = false
 		logger.Info(context.Background(), "Log Correlation has been disabled")
 	}
 }

 func (lfm *LogFeaturesManager) GetTracePublishingStatus() bool {
 	lfm.lock.Lock()
 	defer lfm.lock.Unlock()

 	return lfm.isTracePublishingEnabled
 }

 func (lfm *LogFeaturesManager) SetTracePublishingStatus(isEnabled bool) {
 	lfm.lock.Lock()
 	defer lfm.lock.Unlock()

 	if isEnabled == lfm.isTracePublishingEnabled {
 		logger.Debugf(context.Background(), "Ignoring Trace Publishing Set operation with value %t; current Status same as desired", isEnabled)
 		return
 	}

 	if isEnabled {
 		// Construct new Tracer instance if Tracing Publish has been enabled (even if a Jaeger instance is already active)
 		// This is needed to ensure that a fresh lookup of Jaeger Agent address is performed again while performing
 		// Disable-Enable of Tracing
 		tracer, _, err := lfm.constructJaegerTracer(isEnabled, lfm.activeTraceAgentAddress, false)
 		if err != nil {
 			logger.Warnf(context.Background(), "Trace Publishing Enable operation failed with error: %s", err.Error())
 			return
 		}
 		lfm.replaceActiveTracer(tracer)

 		lfm.isTracePublishingEnabled = true
 		logger.Info(context.Background(), "Tracing Publishing has been enabled")
 	} else {
 		// Switch to NoopTracer when Tracing Publish has been disabled and Log Correlation is already disabled
 		if !lfm.isLogCorrelationEnabled {
 			lfm.replaceActiveTracer(opentracing.NoopTracer{})
 		} else {
 			// Else construct a new Jaeger Instance with publishing disabled
 			tracer, _, err := lfm.constructJaegerTracer(isEnabled, lfm.activeTraceAgentAddress, false)
 			if err != nil {
 				logger.Warnf(context.Background(), "Trace Publishing Disable operation failed with error: %s", err.Error())
 				return
 			}
 			lfm.replaceActiveTracer(tracer)
 		}

 		lfm.isTracePublishingEnabled = false
 		logger.Info(context.Background(), "Tracing Publishing has been disabled")
 	}
 }

 // Method to contruct a new Jaeger Tracer instance based on given Trace Agent address and Publish status.
 // The last attribute indicates whether to use Loopback IP for creating Jaeger Client when the DNS lookup
 // of supplied Trace Agent address has failed. It is fine to fallback during the initialization step, but
 // not later (when enabling/disabling the status dynamically)
 func (lfm *LogFeaturesManager) constructJaegerTracer(tracePublishEnabled bool, traceAgentAddress string, fallbackToLoopbackAllowed bool) (opentracing.Tracer, io.Closer, error) {
 	cfg := jcfg.Configuration{ServiceName: lfm.componentName}

 	var err error
 	var jReporterConfig jcfg.ReporterConfig
 	var jReporterCfgOption jtracing.Reporter

 	logger.Info(context.Background(), "Constructing new Jaeger Tracer instance")

 	// Attempt Trace Agent Address first; will fallback to Loopback IP if it fails
 	jReporterConfig = jcfg.ReporterConfig{LocalAgentHostPort: traceAgentAddress, LogSpans: true}
 	jReporterCfgOption, err = jReporterConfig.NewReporter(lfm.componentName, jtracing.NewNullMetrics(), traceLogger{logger: logger.(*clogger)})

 	if err != nil {
 		if !fallbackToLoopbackAllowed {
 			return nil, nil, errors.New("Reporter Creation for given Trace Agent address " + traceAgentAddress + " failed with error : " + err.Error())
 		}

 		logger.Infow(context.Background(), "Unable to create Reporter with given Trace Agent address",
 			Fields{"error": err, "address": traceAgentAddress})
 		// The Reporter initialization may fail due to Invalid Agent address or non-existent Agent (DNS lookup failure).
 		// It is essential for Tracer Instance to still start for correct Span propagation needed for log correlation.
 		// Thus, falback to use loopback IP for Reporter initialization before throwing back any error
 		tracePublishEnabled = false

 		jReporterConfig.LocalAgentHostPort = "127.0.0.1:6831"
 		jReporterCfgOption, err = jReporterConfig.NewReporter(lfm.componentName, jtracing.NewNullMetrics(), traceLogger{logger: logger.(*clogger)})
 		if err != nil {
 			return nil, nil, errors.New("Failed to initialize Jaeger Tracing due to Reporter creation error : " + err.Error())
 		}
 	}

 	// To start with, we are using Constant Sampling type
 	samplerParam := 0 // 0: Do not publish span, 1: Publish
 	if tracePublishEnabled {
 		samplerParam = 1
 	}
 	jSamplerConfig := jcfg.SamplerConfig{Type: "const", Param: float64(samplerParam)}
 	jSamplerCfgOption, err := jSamplerConfig.NewSampler(lfm.componentName, jtracing.NewNullMetrics())
 	if err != nil {
 		return nil, nil, errors.New("Unable to create Sampler : " + err.Error())
 	}

 	return cfg.NewTracer(jcfg.Reporter(jReporterCfgOption), jcfg.Sampler(jSamplerCfgOption))
 }

 func TerminateTracing(c io.Closer) {
 	err := c.Close()
 	if err != nil {
 		logger.Error(context.Background(), "error-while-closing-jaeger-tracer", Fields{"err": err})
 	}
 }

 // Extracts details of Execution Context as log fields from the Tracing Span injected into the
 // context instance. Following log fields are extracted:
 // 1. Operation Name : key as 'op-name' and value as Span operation name
 // 2. Operation Id : key as 'op-id' and value as 64 bit Span Id in hex digits string
 //
 // Additionally, any tags present in Span are also extracted to use as log fields e.g. device-id.
 //
 // If no Span is found associated with context, blank slice is returned without any log fields
 func (lfm *LogFeaturesManager) ExtractContextAttributes(ctx context.Context) []interface{} {
 	if !lfm.isLogCorrelationEnabled {
 		return make([]interface{}, 0)
 	}

 	attrMap := make(map[string]interface{})

 	if ctx != nil {
 		if span := opentracing.SpanFromContext(ctx); span != nil {
 			if jspan, ok := span.(*jtracing.Span); ok {
 				// Add Log fields for operation identified by Root Level Span (Trace)
 				opId := fmt.Sprintf("%016x", jspan.SpanContext().TraceID().Low) // Using Sprintf to avoid removal of leading 0s
 				opName := jspan.BaggageItem(RootSpanNameKey)

 				taskId := fmt.Sprintf("%016x", uint64(jspan.SpanContext().SpanID())) // Using Sprintf to avoid removal of leading 0s
 				taskName := jspan.OperationName()

 				if opName == "" {
 					span.SetBaggageItem(RootSpanNameKey, taskName)
 					opName = taskName
 				}

 				attrMap["op-id"] = opId
 				attrMap["op-name"] = opName

 				// Add Log fields for task identified by Current Span, if it is different
 				// than operation
 				if taskId != opId {
 					attrMap["task-id"] = taskId
 					attrMap["task-name"] = taskName
 				}

 				for k, v := range jspan.Tags() {
 					// Ignore the special tags added by Jaeger, middleware (sampler.type, span.*) present in the span
 					if strings.HasPrefix(k, "sampler.") || strings.HasPrefix(k, "span.") || k == "component" {
 						continue
 					}

 					attrMap[k] = v
 				}

 				processBaggageItems := func(k, v string) bool {
 					if k != "rpc-span-name" {
 						attrMap[k] = v
 					}
 					return true
 				}

 				jspan.SpanContext().ForeachBaggageItem(processBaggageItems)
 			}
 		}
 	}

 	return serializeMap(attrMap)
 }

 // Method to inject additional log fields into Span e.g. device-id
 func EnrichSpan(ctx context.Context, keyAndValues ...Fields) {
 	span := opentracing.SpanFromContext(ctx)
 	if span != nil {
 		if jspan, ok := span.(*jtracing.Span); ok {
 			// Inject as a BaggageItem when the Span is the Root Span so that it propagates
 			// across the components along with Root Span (called as Trace)
 			// Else, inject as a Tag so that it is attached to the Child Task
 			isRootSpan := false
 			if jspan.SpanContext().TraceID().String() == jspan.SpanContext().SpanID().String() {
 				isRootSpan = true
 			}

 			for _, field := range keyAndValues {
 				for k, v := range field {
 					if isRootSpan {
 						span.SetBaggageItem(k, v.(string))
 					} else {
 						span.SetTag(k, v)
 					}
 				}
 			}
 		}
 	}
 }

 // Method to inject Error into the Span in event of any operation failure
 func MarkSpanError(ctx context.Context, err error) {
 	span := opentracing.SpanFromContext(ctx)
 	if span != nil {
 		span.SetTag("error", true)
 		span.SetTag("err", err)
 	}
 }

 // Creates a Child Span from Parent Span embedded in passed context. Should be used before starting a new major
 // operation in Synchronous or Asynchronous mode (go routine), such as following:
 // 1. Start of all implemented External API methods unless using a interceptor for auto-injection of Span (Server side impl)
 // 2. Just before calling an Third-Party lib which is invoking a External API (etcd, kafka)
 // 3. In start of a Go Routine responsible for performing a major task involving significant duration
 // 4. Any method which is suspected to be time consuming...
 func CreateChildSpan(ctx context.Context, taskName string, keyAndValues ...Fields) (opentracing.Span, context.Context) {
 	if !GetGlobalLFM().GetLogCorrelationStatus() && !GetGlobalLFM().GetTracePublishingStatus() {
 		return opentracing.NoopTracer{}.StartSpan(taskName), ctx
 	}

 	parentSpan := opentracing.SpanFromContext(ctx)
 	childSpan, newCtx := opentracing.StartSpanFromContext(ctx, taskName)

 	if parentSpan == nil || parentSpan.BaggageItem(RootSpanNameKey) == "" {
 		childSpan.SetBaggageItem(RootSpanNameKey, taskName)
 	}

 	EnrichSpan(newCtx, keyAndValues...)
 	return childSpan, newCtx
 }

 // Creates a Async Child Span with Follows-From relationship from Parent Span embedded in passed context.
 // Should be used only in scenarios when
 // a) There is dis-continuation in execution and thus result of Child span does not affect the Parent flow at all
 // b) The execution of Child Span is guaranteed to start after the completion of Parent Span
 // In case of any confusion, use CreateChildSpan method
 // Some situations where this method would be suitable includes Kafka Async RPC call, Propagation of Event across
 // a channel etc.
 func CreateAsyncSpan(ctx context.Context, taskName string, keyAndValues ...Fields) (opentracing.Span, context.Context) {
 	if !GetGlobalLFM().GetLogCorrelationStatus() && !GetGlobalLFM().GetTracePublishingStatus() {
 		return opentracing.NoopTracer{}.StartSpan(taskName), ctx
 	}

 	var asyncSpan opentracing.Span
 	var newCtx context.Context

 	parentSpan := opentracing.SpanFromContext(ctx)

 	// We should always be creating Aysnc span from a Valid parent span. If not, create a Child span instead
 	if parentSpan == nil {
 		logger.Warn(context.Background(), "Async span must be created with a Valid parent span only")
 		asyncSpan, newCtx = opentracing.StartSpanFromContext(ctx, taskName)
 	} else {
 		// Use Background context as the base for Follows-from case; else new span is getting both Child and FollowsFrom relationship
 		asyncSpan, newCtx = opentracing.StartSpanFromContext(context.Background(), taskName, opentracing.FollowsFrom(parentSpan.Context()))
 	}

 	if parentSpan == nil || parentSpan.BaggageItem(RootSpanNameKey) == "" {
 		asyncSpan.SetBaggageItem(RootSpanNameKey, taskName)
 	}

 	EnrichSpan(newCtx, keyAndValues...)
 	return asyncSpan, newCtx
 }

 // Extracts the span from Source context and injects into the supplied Target context.
 // This should be used in situations wherein we are calling a time-sensitive operation (etcd update) and hence
 // had a context.Background() used earlier to avoid any cancellation/timeout of operation by passed context.
 // This will allow propagation of span with a different base context (and not the original context)
 func WithSpanFromContext(targetCtx, sourceCtx context.Context) context.Context {
 	span := opentracing.SpanFromContext(sourceCtx)
 	return opentracing.ContextWithSpan(targetCtx, span)
 }

 // Utility method to convert log Fields into array of interfaces expected by zap logger methods
 func serializeMap(fields Fields) []interface{} {
 	data := make([]interface{}, len(fields)*2)
 	i := 0
 	for k, v := range fields {
 		data[i] = k
 		data[i+1] = v
 		i = i + 2
 	}
 	return data
 }
	/*
	* Copyright 2018-present Open Networking Foundation

	* 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.
	*/

	// File contains utility functions to support Open Tracing in conjunction with
	// Enhanced Logging based on context propagation

	package log

	import (
	"context"
	"errors"
	"fmt"
	"github.com/opentracing/opentracing-go"
	jtracing "github.com/uber/jaeger-client-go"
	jcfg "github.com/uber/jaeger-client-go/config"
	"io"
	"os"
	"strings"
	"sync"
	)

	const (
	RootSpanNameKey = "op-name"
	)

	// Global Settings governing the Log Correlation and Tracing features. Should only
	// be updated through the exposed public methods
	type LogFeaturesManager struct {
	isTracePublishingEnabled bool
	isLogCorrelationEnabled bool
	componentName string // Name of component extracted from ENV variable
	activeTraceAgentAddress string
	lock sync.Mutex
	}

	var globalLFM *LogFeaturesManager = &LogFeaturesManager{}

	func GetGlobalLFM() *LogFeaturesManager {
	return globalLFM
	}

	// A Wrapper to utilize currently Active Tracer instance. The middleware library being used for generating
	// Spans for GRPC API calls does not support dynamically setting the Active Tracer similar to the SetGlobalTracer method
	// provided by OpenTracing API
	type ActiveTracerProxy struct {
	}

	func (atw ActiveTracerProxy) StartSpan(operationName string, opts ...opentracing.StartSpanOption) opentracing.Span {
	return opentracing.GlobalTracer().StartSpan(operationName, opts...)
	}

	func (atw ActiveTracerProxy) Inject(sm opentracing.SpanContext, format interface{}, carrier interface{}) error {
	return opentracing.GlobalTracer().Inject(sm, format, carrier)
	}

	func (atw ActiveTracerProxy) Extract(format interface{}, carrier interface{}) (opentracing.SpanContext, error) {
	return opentracing.GlobalTracer().Extract(format, carrier)
	}

	// Jaeger complaint Logger instance to redirect logs to Default Logger
	type traceLogger struct {
	logger *clogger
	}

	func (tl traceLogger) Error(msg string) {
	tl.logger.Error(context.Background(), msg)
	}

	func (tl traceLogger) Infof(msg string, args ...interface{}) {
	// Tracing logs should be performed only at Debug Verbosity
	tl.logger.Debugf(context.Background(), msg, args...)
	}

	// Wrapper to handle correct Closer call at the time of Process Termination
	type traceCloser struct {
	}

	func (c traceCloser) Close() error {
	currentActiveTracer := opentracing.GlobalTracer()
	if currentActiveTracer != nil {
	if jTracer, ok := currentActiveTracer.(*jtracing.Tracer); ok {
	jTracer.Close()
	}
	}

	return nil
	}

	// Method to Initialize Jaeger based Tracing client based on initial status of Tracing Publish and Log Correlation
	func (lfm *LogFeaturesManager) InitTracingAndLogCorrelation(tracePublishEnabled bool, traceAgentAddress string, logCorrelationEnabled bool) (io.Closer, error) {
	lfm.componentName = os.Getenv("COMPONENT_NAME")
	if lfm.componentName == "" {
	return nil, errors.New("Unable to retrieve PoD Component Name from Runtime env")
	}

	lfm.lock.Lock()
	defer lfm.lock.Unlock()

	// Use NoopTracer when both Tracing Publishing and Log Correlation are disabled
	if !tracePublishEnabled && !logCorrelationEnabled {
	logger.Info(context.Background(), "Skipping Global Tracer initialization as both Trace publish and Log correlation are configured as disabled")
	lfm.isTracePublishingEnabled = false
	lfm.isLogCorrelationEnabled = false
	opentracing.SetGlobalTracer(opentracing.NoopTracer{})
	return traceCloser{}, nil
	}

	tracer, _, err := lfm.constructJaegerTracer(tracePublishEnabled, traceAgentAddress, true)
	if err != nil {
	return nil, err
	}

	// Initialize variables representing Active Status
	opentracing.SetGlobalTracer(tracer)
	lfm.isTracePublishingEnabled = tracePublishEnabled
	lfm.activeTraceAgentAddress = traceAgentAddress
	lfm.isLogCorrelationEnabled = logCorrelationEnabled
	return traceCloser{}, nil
	}

	// Method to replace Active Tracer along with graceful closer of previous tracer
	func (lfm *LogFeaturesManager) replaceActiveTracer(tracer opentracing.Tracer) {
	currentActiveTracer := opentracing.GlobalTracer()
	opentracing.SetGlobalTracer(tracer)

	if currentActiveTracer != nil {
	if jTracer, ok := currentActiveTracer.(*jtracing.Tracer); ok {
	jTracer.Close()
	}
	}
	}

	func (lfm *LogFeaturesManager) GetLogCorrelationStatus() bool {
	lfm.lock.Lock()
	defer lfm.lock.Unlock()

	return lfm.isLogCorrelationEnabled
	}

	func (lfm *LogFeaturesManager) SetLogCorrelationStatus(isEnabled bool) {
	lfm.lock.Lock()
	defer lfm.lock.Unlock()

	if isEnabled == lfm.isLogCorrelationEnabled {
	logger.Debugf(context.Background(), "Ignoring Log Correlation Set operation with value %t; current Status same as desired", isEnabled)
	return
	}

	if isEnabled {
	// Construct new Tracer instance if Log Correlation has been enabled and current active tracer is a NoopTracer instance.
	// Continue using the earlier tracer instance in case of any error
	if _, ok := opentracing.GlobalTracer().(opentracing.NoopTracer); ok {
	tracer, _, err := lfm.constructJaegerTracer(lfm.isTracePublishingEnabled, lfm.activeTraceAgentAddress, false)
	if err != nil {
	logger.Warnf(context.Background(), "Log Correlation Enable operation failed with error: %s", err.Error())
	return
	}

	lfm.replaceActiveTracer(tracer)
	}

	lfm.isLogCorrelationEnabled = true
	logger.Info(context.Background(), "Log Correlation has been enabled")

	} else {
	// Switch to NoopTracer when Log Correlation has been disabled and Tracing Publish is already disabled
	if _, ok := opentracing.GlobalTracer().(opentracing.NoopTracer); !ok && !lfm.isTracePublishingEnabled {
	lfm.replaceActiveTracer(opentracing.NoopTracer{})
	}

	lfm.isLogCorrelationEnabled = false
	logger.Info(context.Background(), "Log Correlation has been disabled")
	}
	}

	func (lfm *LogFeaturesManager) GetTracePublishingStatus() bool {
	lfm.lock.Lock()
	defer lfm.lock.Unlock()

	return lfm.isTracePublishingEnabled
	}

	func (lfm *LogFeaturesManager) SetTracePublishingStatus(isEnabled bool) {
	lfm.lock.Lock()
	defer lfm.lock.Unlock()

	if isEnabled == lfm.isTracePublishingEnabled {
	logger.Debugf(context.Background(), "Ignoring Trace Publishing Set operation with value %t; current Status same as desired", isEnabled)
	return
	}

	if isEnabled {
	// Construct new Tracer instance if Tracing Publish has been enabled (even if a Jaeger instance is already active)
	// This is needed to ensure that a fresh lookup of Jaeger Agent address is performed again while performing
	// Disable-Enable of Tracing
	tracer, _, err := lfm.constructJaegerTracer(isEnabled, lfm.activeTraceAgentAddress, false)
	if err != nil {
	logger.Warnf(context.Background(), "Trace Publishing Enable operation failed with error: %s", err.Error())
	return
	}
	lfm.replaceActiveTracer(tracer)

	lfm.isTracePublishingEnabled = true
	logger.Info(context.Background(), "Tracing Publishing has been enabled")
	} else {
	// Switch to NoopTracer when Tracing Publish has been disabled and Log Correlation is already disabled
	if !lfm.isLogCorrelationEnabled {
	lfm.replaceActiveTracer(opentracing.NoopTracer{})
	} else {
	// Else construct a new Jaeger Instance with publishing disabled
	tracer, _, err := lfm.constructJaegerTracer(isEnabled, lfm.activeTraceAgentAddress, false)
	if err != nil {
	logger.Warnf(context.Background(), "Trace Publishing Disable operation failed with error: %s", err.Error())
	return
	}
	lfm.replaceActiveTracer(tracer)
	}

	lfm.isTracePublishingEnabled = false
	logger.Info(context.Background(), "Tracing Publishing has been disabled")
	}
	}

	// Method to contruct a new Jaeger Tracer instance based on given Trace Agent address and Publish status.
	// The last attribute indicates whether to use Loopback IP for creating Jaeger Client when the DNS lookup
	// of supplied Trace Agent address has failed. It is fine to fallback during the initialization step, but
	// not later (when enabling/disabling the status dynamically)
	func (lfm *LogFeaturesManager) constructJaegerTracer(tracePublishEnabled bool, traceAgentAddress string, fallbackToLoopbackAllowed bool) (opentracing.Tracer, io.Closer, error) {
	cfg := jcfg.Configuration{ServiceName: lfm.componentName}

	var err error
	var jReporterConfig jcfg.ReporterConfig
	var jReporterCfgOption jtracing.Reporter

	logger.Info(context.Background(), "Constructing new Jaeger Tracer instance")

	// Attempt Trace Agent Address first; will fallback to Loopback IP if it fails
	jReporterConfig = jcfg.ReporterConfig{LocalAgentHostPort: traceAgentAddress, LogSpans: true}
	jReporterCfgOption, err = jReporterConfig.NewReporter(lfm.componentName, jtracing.NewNullMetrics(), traceLogger{logger: logger.(*clogger)})

	if err != nil {
	if !fallbackToLoopbackAllowed {
	return nil, nil, errors.New("Reporter Creation for given Trace Agent address " + traceAgentAddress + " failed with error : " + err.Error())
	}

	logger.Infow(context.Background(), "Unable to create Reporter with given Trace Agent address",
	Fields{"error": err, "address": traceAgentAddress})
	// The Reporter initialization may fail due to Invalid Agent address or non-existent Agent (DNS lookup failure).
	// It is essential for Tracer Instance to still start for correct Span propagation needed for log correlation.
	// Thus, falback to use loopback IP for Reporter initialization before throwing back any error
	tracePublishEnabled = false

	jReporterConfig.LocalAgentHostPort = "127.0.0.1:6831"
	jReporterCfgOption, err = jReporterConfig.NewReporter(lfm.componentName, jtracing.NewNullMetrics(), traceLogger{logger: logger.(*clogger)})
	if err != nil {
	return nil, nil, errors.New("Failed to initialize Jaeger Tracing due to Reporter creation error : " + err.Error())
	}
	}

	// To start with, we are using Constant Sampling type
	samplerParam := 0 // 0: Do not publish span, 1: Publish
	if tracePublishEnabled {
	samplerParam = 1
	}
	jSamplerConfig := jcfg.SamplerConfig{Type: "const", Param: float64(samplerParam)}
	jSamplerCfgOption, err := jSamplerConfig.NewSampler(lfm.componentName, jtracing.NewNullMetrics())
	if err != nil {
	return nil, nil, errors.New("Unable to create Sampler : " + err.Error())
	}

	return cfg.NewTracer(jcfg.Reporter(jReporterCfgOption), jcfg.Sampler(jSamplerCfgOption))
	}

	func TerminateTracing(c io.Closer) {
	err := c.Close()
	if err != nil {
	logger.Error(context.Background(), "error-while-closing-jaeger-tracer", Fields{"err": err})
	}
	}

	// Extracts details of Execution Context as log fields from the Tracing Span injected into the
	// context instance. Following log fields are extracted:
	// 1. Operation Name : key as 'op-name' and value as Span operation name
	// 2. Operation Id : key as 'op-id' and value as 64 bit Span Id in hex digits string
	//
	// Additionally, any tags present in Span are also extracted to use as log fields e.g. device-id.
	//
	// If no Span is found associated with context, blank slice is returned without any log fields
	func (lfm *LogFeaturesManager) ExtractContextAttributes(ctx context.Context) []interface{} {
	if !lfm.isLogCorrelationEnabled {
	return make([]interface{}, 0)
	}

	attrMap := make(map[string]interface{})

	if ctx != nil {
	if span := opentracing.SpanFromContext(ctx); span != nil {
	if jspan, ok := span.(*jtracing.Span); ok {
	// Add Log fields for operation identified by Root Level Span (Trace)
	opId := fmt.Sprintf("%016x", jspan.SpanContext().TraceID().Low) // Using Sprintf to avoid removal of leading 0s
	opName := jspan.BaggageItem(RootSpanNameKey)

	taskId := fmt.Sprintf("%016x", uint64(jspan.SpanContext().SpanID())) // Using Sprintf to avoid removal of leading 0s
	taskName := jspan.OperationName()

	if opName == "" {
	span.SetBaggageItem(RootSpanNameKey, taskName)
	opName = taskName
	}

	attrMap["op-id"] = opId
	attrMap["op-name"] = opName

	// Add Log fields for task identified by Current Span, if it is different
	// than operation
	if taskId != opId {
	attrMap["task-id"] = taskId
	attrMap["task-name"] = taskName
	}

	for k, v := range jspan.Tags() {
	// Ignore the special tags added by Jaeger, middleware (sampler.type, span.*) present in the span
	if strings.HasPrefix(k, "sampler.") \|\| strings.HasPrefix(k, "span.") \|\| k == "component" {
	continue
	}

	attrMap[k] = v
	}

	processBaggageItems := func(k, v string) bool {
	if k != "rpc-span-name" {
	attrMap[k] = v
	}
	return true
	}

	jspan.SpanContext().ForeachBaggageItem(processBaggageItems)
	}
	}
	}

	return serializeMap(attrMap)
	}

	// Method to inject additional log fields into Span e.g. device-id
	func EnrichSpan(ctx context.Context, keyAndValues ...Fields) {
	span := opentracing.SpanFromContext(ctx)
	if span != nil {
	if jspan, ok := span.(*jtracing.Span); ok {
	// Inject as a BaggageItem when the Span is the Root Span so that it propagates
	// across the components along with Root Span (called as Trace)
	// Else, inject as a Tag so that it is attached to the Child Task
	isRootSpan := false
	if jspan.SpanContext().TraceID().String() == jspan.SpanContext().SpanID().String() {
	isRootSpan = true
	}

	for _, field := range keyAndValues {
	for k, v := range field {
	if isRootSpan {
	span.SetBaggageItem(k, v.(string))
	} else {
	span.SetTag(k, v)
	}
	}
	}
	}
	}
	}

	// Method to inject Error into the Span in event of any operation failure
	func MarkSpanError(ctx context.Context, err error) {
	span := opentracing.SpanFromContext(ctx)
	if span != nil {
	span.SetTag("error", true)
	span.SetTag("err", err)
	}
	}

	// Creates a Child Span from Parent Span embedded in passed context. Should be used before starting a new major
	// operation in Synchronous or Asynchronous mode (go routine), such as following:
	// 1. Start of all implemented External API methods unless using a interceptor for auto-injection of Span (Server side impl)
	// 2. Just before calling an Third-Party lib which is invoking a External API (etcd, kafka)
	// 3. In start of a Go Routine responsible for performing a major task involving significant duration
	// 4. Any method which is suspected to be time consuming...
	func CreateChildSpan(ctx context.Context, taskName string, keyAndValues ...Fields) (opentracing.Span, context.Context) {
	if !GetGlobalLFM().GetLogCorrelationStatus() && !GetGlobalLFM().GetTracePublishingStatus() {
	return opentracing.NoopTracer{}.StartSpan(taskName), ctx
	}

	parentSpan := opentracing.SpanFromContext(ctx)
	childSpan, newCtx := opentracing.StartSpanFromContext(ctx, taskName)

	if parentSpan == nil \|\| parentSpan.BaggageItem(RootSpanNameKey) == "" {
	childSpan.SetBaggageItem(RootSpanNameKey, taskName)
	}

	EnrichSpan(newCtx, keyAndValues...)
	return childSpan, newCtx
	}

	// Creates a Async Child Span with Follows-From relationship from Parent Span embedded in passed context.
	// Should be used only in scenarios when
	// a) There is dis-continuation in execution and thus result of Child span does not affect the Parent flow at all
	// b) The execution of Child Span is guaranteed to start after the completion of Parent Span
	// In case of any confusion, use CreateChildSpan method
	// Some situations where this method would be suitable includes Kafka Async RPC call, Propagation of Event across
	// a channel etc.
	func CreateAsyncSpan(ctx context.Context, taskName string, keyAndValues ...Fields) (opentracing.Span, context.Context) {
	if !GetGlobalLFM().GetLogCorrelationStatus() && !GetGlobalLFM().GetTracePublishingStatus() {
	return opentracing.NoopTracer{}.StartSpan(taskName), ctx
	}

	var asyncSpan opentracing.Span
	var newCtx context.Context

	parentSpan := opentracing.SpanFromContext(ctx)

	// We should always be creating Aysnc span from a Valid parent span. If not, create a Child span instead
	if parentSpan == nil {
	logger.Warn(context.Background(), "Async span must be created with a Valid parent span only")
	asyncSpan, newCtx = opentracing.StartSpanFromContext(ctx, taskName)
	} else {
	// Use Background context as the base for Follows-from case; else new span is getting both Child and FollowsFrom relationship
	asyncSpan, newCtx = opentracing.StartSpanFromContext(context.Background(), taskName, opentracing.FollowsFrom(parentSpan.Context()))
	}

	if parentSpan == nil \|\| parentSpan.BaggageItem(RootSpanNameKey) == "" {
	asyncSpan.SetBaggageItem(RootSpanNameKey, taskName)
	}

	EnrichSpan(newCtx, keyAndValues...)
	return asyncSpan, newCtx
	}

	// Extracts the span from Source context and injects into the supplied Target context.
	// This should be used in situations wherein we are calling a time-sensitive operation (etcd update) and hence
	// had a context.Background() used earlier to avoid any cancellation/timeout of operation by passed context.
	// This will allow propagation of span with a different base context (and not the original context)
	func WithSpanFromContext(targetCtx, sourceCtx context.Context) context.Context {
	span := opentracing.SpanFromContext(sourceCtx)
	return opentracing.ContextWithSpan(targetCtx, span)
	}

	// Utility method to convert log Fields into array of interfaces expected by zap logger methods
	func serializeMap(fields Fields) []interface{} {
	data := make([]interface{}, len(fields)*2)
	i := 0
	for k, v := range fields {
	data[i] = k
	data[i+1] = v
	i = i + 2
	}
	return data
	}