otredis.go

package otredis

import (
	"context"
	"strings"

	"github.com/go-redis/redis"
	"github.com/opentracing/opentracing-go"
	"github.com/opentracing/opentracing-go/ext"
)

// WrapRedisClient adds opentracing measurements for commands and returns cloned client
func WrapRedisClient(ctx context.Context, client *redis.Client) *redis.Client {
	if ctx == nil {
		return client
	}
	parentSpan := opentracing.SpanFromContext(ctx)
	if parentSpan == nil {
		return client
	}
	// clone using context
	ctxClient := client.WithContext(ctx)
	opts := ctxClient.Options()
	ctxClient.WrapProcess(process(parentSpan, opts))
	ctxClient.WrapProcessPipeline(processPipeline(parentSpan, opts))
	return ctxClient
}

func process(parentSpan opentracing.Span, opts *redis.Options) func(oldProcess func(cmd redis.Cmder) error) func(cmd redis.Cmder) error {
	return func(oldProcess func(cmd redis.Cmder) error) func(cmd redis.Cmder) error {
		return func(cmd redis.Cmder) error {
			tracer := parentSpan.Tracer()
			span := tracer.StartSpan("redis-cmd", opentracing.ChildOf(parentSpan.Context()))
			defer span.Finish()
			dbMethod := formatCommandAsDbMethod(cmd)
			configureSpanTags(span, opts, dbMethod)
			return oldProcess(cmd)
		}
	}
}

func processPipeline(parentSpan opentracing.Span, opts *redis.Options) func(oldProcess func(cmds []redis.Cmder) error) func(cmds []redis.Cmder) error {
	return func(oldProcess func(cmds []redis.Cmder) error) func(cmds []redis.Cmder) error {
		return func(cmds []redis.Cmder) error {
			tracer := parentSpan.Tracer()
			span := tracer.StartSpan("redis-pipeline-cmd", opentracing.ChildOf(parentSpan.Context()))
			defer span.Finish()
			dbMethod := formatCommandsAsDbMethods(cmds)
			configureSpanTags(span, opts, dbMethod)
			return oldProcess(cmds)
		}
	}
}

func formatCommandAsDbMethod(cmd redis.Cmder) string {
	return cmd.Name()
}

func formatCommandsAsDbMethods(cmds []redis.Cmder) string {
	cmdsAsDbMethods := make([]string, len(cmds))
	for i, cmd := range cmds {
		dbMethod := formatCommandAsDbMethod(cmd)
		cmdsAsDbMethods[i] = dbMethod
	}
	return strings.Join(cmdsAsDbMethods, " -> ")
}

func configureSpanTags(span opentracing.Span, opts *redis.Options, dbMethod string) {
	ext.DBType.Set(span, "redis")
	ext.PeerAddress.Set(span, opts.Addr)
	ext.SpanKind.Set(span, ext.SpanKindEnum("client"))
	span.SetTag("db.method", dbMethod)
}