feat: add example for beego instrumentation (#243)

* feat: add dockerized example

* chore: Update readme

* fix: remove tracing on client

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

instrumentation/github.com/astaxie/beego/example/Dockerfile

@@ -0,0 +1,25 @@
+# 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.
+
+FROM golang:1.14-alpine AS base
+COPY . /src/
+WORKDIR /src/instrumentation/github.com/astaxie/beego/example
+
+FROM base AS example-beego-server
+RUN go install ./server/server.go
+CMD ["/go/bin/server"]
+
+FROM base AS example-http-client
+RUN go install ./client/client.go
+CMD ["/go/bin/client"]

instrumentation/github.com/astaxie/beego/example/README.md

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+# Beego Server Instrumentation Example
+
+An HTTP client connects to a Beego server. They both generate span information to `stdout`.
+These instructions expect you have [docker-compose](https://docs.docker.com/compose/) installed.
+
+Bring up the `beego-server` and `http-client` services to run the example:
+```sh
+docker-compose up -d
+```
+
+The `http-client` service sends just one HTTP request to `beego-server` and then exits. View the span generated by `beego-server` in the logs:
+```sh
+docker-compose logs beego-server
+```
+
+You can also visit a webpage hosted by the Beego app by navigating to `http://localhost:7777` in your browser. 
+Two spans are created this time, one for the HTTP request, and another for rendering the template HTML. You can view the spans the same way as above.
+
+Shut down the services when you are finished with the example:
+```sh
+docker-compose down
+```

instrumentation/github.com/astaxie/beego/example/client/client.go

@@ -0,0 +1,50 @@
+// 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 (
+	"flag"
+	"fmt"
+	"io/ioutil"
+	"log"
+
+	"net/http"
+)
+
+func main() {
+	url := flag.String("server", "http://localhost:7777/hello", "server url")
+	flag.Parse()
+
+	client := http.Client{}
+
+	req, err := http.NewRequest("GET", *url, nil)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	fmt.Printf("sending request...\n")
+	res, err := client.Do(req)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	body, err := ioutil.ReadAll(res.Body)
+	if err != nil {
+		log.Fatal(err)
+	}
+	_ = res.Body.Close()
+
+	fmt.Printf("Response Received: %s\n\n\n", body)
+}

instrumentation/github.com/astaxie/beego/example/docker-compose.yml

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+# 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.
+
+version: "3.7"
+services:
+  beego-server:
+    build:
+      dockerfile: $PWD/Dockerfile
+      context: ../../../../..
+      target: example-beego-server
+    command: ["/go/bin/server", "-zipkin", "zipkin:9411"]
+    ports:
+      - 7777:7777
+
+  http-client:
+    build:
+      dockerfile: $PWD/Dockerfile
+      context: ../../../../..
+      target: example-http-client
+    command: ["/go/bin/client", "-server", "http://beego-server:7777/hello"]
+    depends_on:
+      - beego-server
+

instrumentation/github.com/astaxie/beego/example/go.mod

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+module go.opentelemetry.io/contrib/instrumentation/astaxie/beego/example
+
+go 1.14
+
+require (
+	github.com/astaxie/beego v1.12.2
+	go.opentelemetry.io/contrib/instrumentation/github.com/astaxie/beego v0.0.0-00010101000000-000000000000
+	go.opentelemetry.io/otel v0.10.0
+	go.opentelemetry.io/otel/exporters/stdout v0.10.0
+	go.opentelemetry.io/otel/sdk v0.10.0
+)
+
+replace (
+	go.opentelemetry.io/contrib => ../../../../../
+	go.opentelemetry.io/contrib/instrumentation/github.com/astaxie/beego => ../
+)