[add] Sample distributed tracing of a sample Golang HTTP App that uses a Redis backend

Author: filipecosta90

.dockerignore

@@ -0,0 +1,11 @@
+.editorconfig
+.git
+AUTHORS.md
+CONTRIBUTING.md
+LICENSE
+NOTICE
+README.md
+arm/
+powerpc/
+mips/
+opentelemetry-go-http-sample

.gitignore

@@ -12,4 +12,9 @@
 *.out
 
 # Dependency directories (remove the comment below to include it)
-# vendor/
+ vendor/
+
+ opentelemetry-go-http-sample
+
+.idea
+bin/

Dockerfile

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+FROM golang:1.15.6-buster AS build
+WORKDIR /src
+COPY . .
+RUN make build
+ENTRYPOINT ["/src/bin//opentelemetry-go-http-sample"]

Makefile

@@ -0,0 +1,53 @@
+# Go parameters
+GOCMD=GO111MODULE=on go
+GOBUILD=$(GOCMD) build
+GOINSTALL=$(GOCMD) install
+GOCLEAN=$(GOCMD) clean
+GOTEST=$(GOCMD) test
+GOGET=$(GOCMD) get
+GOMOD=$(GOCMD) mod
+GOFMT=$(GOCMD) fmt
+
+.PHONY: all test coverage
+all: test coverage build
+
+build:
+	$(GOBUILD) -o bin/opentelemetry-go-http-sample .
+
+start-docker:
+	@docker-compose -f docker-compose.yml up
+
+stop-docker:
+	@docker-compose -f docker-compose.yml down
+
+
+build-docker:
+	@docker-compose -f docker-compose.yml build
+
+checkfmt:
+	@echo 'Checking gofmt';\
+ 	bash -c "diff -u <(echo -n) <(gofmt -d .)";\
+	EXIT_CODE=$$?;\
+	if [ "$$EXIT_CODE"  -ne 0 ]; then \
+		echo '$@: Go files must be formatted with gofmt'; \
+	fi && \
+	exit $$EXIT_CODE
+
+lint:
+	$(GOGET) github.com/golangci/golangci-lint/cmd/golangci-lint
+	golangci-lint run
+
+get:
+	$(GOGET) -t -v ./...
+
+test: get
+	$(GOFMT) ./...
+	$(GOTEST) ./...
+
+coverage: get test
+	$(GOTEST) -race -coverprofile=coverage.txt -covermode=atomic .
+
+fmt:
+	$(GOFMT) ./...
+
+

Readme.md

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+# OpenTelemetry Golang net/http + go-redis example
+
+
+This demo showcases OpenTelemetry distributed tracing of a sample 
+Golang HTTP App that uses a Redis backend, 
+using W3C TraceContext as the de-facto standard for trace propagation across process boundaries.
+
+This setup relies on Jaeger to receive and visualize traces. 
+
+Make sure to check https://opentelemetry.io/docs/go/ for further reference and examples.
+ 
+## 1 ) How to build and the sample app using docker 
+```
+git clone github.com/filipecosta90/opentelemetry-go-http-sample
+cd opentelemetry-go-http-sample
+make build-docker
+make start-docker
+```
+
+
+## 2 ) Generating sample traces
+You should now jave your sample app listening on port :7777, redis on port :6379, 
+and Jaeger on ports :14268, :16686.
+Let's generate some sample traces:
+
+```
+$ curl -X POST -d "{\"Name\":\"John Doe\", \"Username\":\"johndoe\", \"About\":\"Redis Geek\"}" http://localhost:7777/author/1
+$ curl -X GET http://localhost:7777/author/1
+```
+
+## 3) Go look for your traces!
+ 
+The Jaeger visualization URL is at (notice the port number):
+
+http://[hostname]:16686/search 
+ 
+Put in `sampleHTTPServer` value into the service name, and search for your recent traces!
+Click one, and you should see the following:
+ 
+![sample jaeger output](./docs/sample-jaeger-output.jpg)

author.go

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+package main
+
+import "fmt"
+
+// The Author struct represents the data in the JSON/JSONB column.
+// We can use struct tags to control how each field is encoded.
+type Author struct {
+	Name     string `json:"Name"`
+	Username string `json:"Username"`
+	About    string `json:"About"`
+}
+
+func authorToHsetCmdArgs(author Author) []interface{} {
+	nonNullValues := make([]interface{}, 0)
+	if author.Name != "" {
+		nonNullValues = append(nonNullValues, "Name", author.Name)
+	}
+	if author.Username != "" {
+		nonNullValues = append(nonNullValues, "Username", author.Username)
+	}
+	if author.About != "" {
+		nonNullValues = append(nonNullValues, "About", author.About)
+	}
+	return nonNullValues
+}
+
+func getRedisAuthorKey(authorId int) string {
+	return fmt.Sprintf("author:%d", authorId)
+}
+
+func UpdateAuthorFromRedisReply(author Author, redisReply map[string]string) (updatedAuthor Author, err error) {
+	updatedAuthor = author
+	if name, ok := redisReply["Name"]; ok {
+		updatedAuthor.Name = name
+	}
+	if username, ok := redisReply["Username"]; ok {
+		updatedAuthor.Username = username
+	}
+	if about, ok := redisReply["About"]; ok {
+		updatedAuthor.About = about
+	}
+	return
+}

docker-compose.yml

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+version: '3'
+services:
+  redis:
+    image: redis:6.0.5
+    ports:
+      - 6379:6379/tcp
+
+  server:
+    build: .
+    depends_on:
+      - redis
+      - jaeger
+    ports:
+      - 7777:7777
+    environment:
+      REDISENDPOINT: redis:6379
+      JAEGERAGENTENDPOINT: http://jaeger:14268
+    command: ['./opentelemetry-go-http-sample']
+
+  jaeger:
+    image: jaegertracing/opentelemetry-all-in-one
+    ports:
+      - 14268:14268
+      - 16686:16686

docs/sample-jaeger-output.jpg

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+module github.com/filipecosta90/opentelemetry-go-http-sample
+
+go 1.13
+
+require (
+	github.com/go-redis/redis/extra/redisotel v0.2.0
+	github.com/go-redis/redis/v8 v8.4.2
+	github.com/golangci/golangci-lint v1.33.0 // indirect
+	github.com/gorilla/mux v1.8.0
+	github.com/namsral/flag v1.7.4-pre
+	go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp v0.15.0
+	go.opentelemetry.io/otel v0.15.0
+	go.opentelemetry.io/otel/exporters/trace/jaeger v0.15.0
+	go.opentelemetry.io/otel/sdk v0.15.0
+)