Add a simple HTTP example (#195)

* Add a simple HTTP example

* fix lint + create a server instance

* remove un-needed files

---------

Co-authored-by: Tyler Yahn <MrAlias@users.noreply.github.com>

examples/rolldice/Dockerfile

@@ -0,0 +1,5 @@
+FROM golang:1.20
+WORKDIR /app
+COPY . .
+RUN go build -o main
+ENTRYPOINT ["/app/main"]

examples/rolldice/README.md

@@ -0,0 +1,19 @@
+# Example of Auto instrumentation of HTTP server
+
+Rolldice server exposes an endpoint `/rolldice.` When we hit the endpoint, it returns a random number between 1-6. 
+
+For testing auto instrumentation, we can use the docker compose. 
+
+To run the example, bring up the services using the command.
+
+```
+docker compose up 
+```
+
+Now, you can hit roll dice server using the below command
+```
+curl localhost:8080/rolldice
+```
+Every hit to the server should generate a trace that we can observe in [Jaeger UI](http://localhost:16686/)
+
+Example trace ![Image](jaeger.jpg)

examples/rolldice/docker-compose.yaml

@@ -0,0 +1,54 @@
+version: "3.9"
+
+networks:
+  default:
+    name: roll
+    driver: bridge
+
+services:
+  rolldice:
+    depends_on:
+      - jaeger
+    build:
+      context: .
+      dockerfile: ./Dockerfile
+    pid: "host"
+    ports:
+      - "8080:8080"
+    volumes:
+      - shared-data:/app
+      - /proc:/host/proc
+  go-auto:
+    depends_on:
+      - rolldice
+    build:
+      context: ../..
+      dockerfile: Dockerfile
+    privileged: true
+    pid: "host"
+    environment:
+      - OTEL_EXPORTER_OTLP_ENDPOINT=http://jaeger:4317
+      - OTEL_GO_AUTO_TARGET_EXE=/app/main
+      - OTEL_SERVICE_NAME=rolldice
+      - OTEL_PROPAGATORS=tracecontext,baggage
+    volumes:
+      - shared-data:/app
+      - /proc:/host/proc
+
+  jaeger:
+    image: jaegertracing/all-in-one:latest
+    ports:
+      - "16686:16686"
+      - "14268:14268"
+    environment:
+      - COLLECTOR_OTLP_ENABLED=true
+      - LOG_LEVEL=debug
+    deploy:
+      resources:
+        limits:
+          memory: 300M
+    restart: unless-stopped
+
+
+volumes:
+  shared-data:

examples/rolldice/go.mod

@@ -0,0 +1,10 @@
+module go.openetelemetry.io/auto/examples/rolldice
+
+go 1.20
+
+require go.uber.org/zap v1.24.0
+
+require (
+	go.uber.org/atomic v1.7.0 // indirect
+	go.uber.org/multierr v1.6.0 // indirect
+)

examples/rolldice/go.sum

@@ -0,0 +1,18 @@
+github.com/benbjohnson/clock v1.1.0 h1:Q92kusRqC1XV2MjkWETPvjJVqKetz1OzxZB7mHJLju8=
+github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/pkg/errors v0.8.1 h1:iURUrRGxPUNPdy5/HRSm+Yj6okJ6UtLINN0Q9M4+h3I=
+github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
+github.com/stretchr/testify v1.3.0/go.mod h1:M5WIy9Dh21IEIfnGCwXGc5bZfKNJtfHm1UVUgZn+9EI=
+github.com/stretchr/testify v1.8.0 h1:pSgiaMZlXftHpm5L7V1+rVB+AZJydKsMxsQBIJw4PKk=
+go.uber.org/atomic v1.7.0 h1:ADUqmZGgLDDfbSL9ZmPxKTybcoEYHgpYfELNoN+7hsw=
+go.uber.org/atomic v1.7.0/go.mod h1:fEN4uk6kAWBTFdckzkM89CLk9XfWZrxpCo0nPH17wJc=
+go.uber.org/goleak v1.1.11 h1:wy28qYRKZgnJTxGxvye5/wgWr1EKjmUDGYox5mGlRlI=
+go.uber.org/multierr v1.6.0 h1:y6IPFStTAIT5Ytl7/XYmHvzXQ7S3g/IeZW9hyZ5thw4=
+go.uber.org/multierr v1.6.0/go.mod h1:cdWPpRnG4AhwMwsgIHip0KRBQjJy5kYEpYjJxpXp9iU=
+go.uber.org/zap v1.24.0 h1:FiJd5l1UOLj0wCgbSE0rwwXHzEdAZS6hiiSnxJN/D60=
+go.uber.org/zap v1.24.0/go.mod h1:2kMP+WWQ8aoFoedH3T2sq6iJ2yDWpHbP0f6MQbS9Gkg=
+gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=

examples/rolldice/main.go

@@ -0,0 +1,68 @@
+// Copyright The OpenTelemetry Authors
+//
+// 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 main
+
+import (
+	"fmt"
+	"math/rand"
+	"net/http"
+	"time"
+
+	"go.uber.org/zap"
+)
+
+// Server is Http server that exposes multiple endpoints.
+type Server struct {
+	rand *rand.Rand
+}
+
+// NewServer creates a server struct after initialing rand.
+func NewServer() *Server {
+	rd := rand.New(rand.NewSource(time.Now().Unix()))
+	return &Server{
+		rand: rd,
+	}
+}
+
+func (s *Server) rolldice(w http.ResponseWriter, _ *http.Request) {
+	n := s.rand.Intn(6)
+	logger.Info("rolldice called", zap.Int("dice", n))
+	fmt.Fprintf(w, "%v", n)
+}
+
+var logger *zap.Logger
+
+func setupHandler(s *Server) *http.ServeMux {
+	mux := http.NewServeMux()
+	mux.HandleFunc("/rolldice", s.rolldice)
+	return mux
+}
+
+func main() {
+	var err error
+	logger, err = zap.NewDevelopment()
+	if err != nil {
+		fmt.Printf("error creating zap logger, error:%v", err)
+		return
+	}
+	port := fmt.Sprintf(":%d", 8080)
+	logger.Info("starting http server", zap.String("port", port))
+
+	s := NewServer()
+	mux := setupHandler(s)
+	if err := http.ListenAndServe(port, mux); err != nil {
+		logger.Error("error running server", zap.Error(err))
+	}
+}