c2a3e4e811
This example shows a simple two tier setup in Kubernetes, and simply prints the environment information that each pod sees. Querying the service multiple times will show services at work load balancing requests.
96 lines
2.4 KiB
Go
96 lines
2.4 KiB
Go
/*
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Copyright 2015 The Kubernetes Authors All rights reserved.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package main
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import (
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"fmt"
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"io"
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"log"
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"net/http"
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"os"
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"sort"
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"strings"
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)
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func getKubeEnv() (map[string]string, error) {
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environS := os.Environ()
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environ := make(map[string]string)
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for _, val := range environS {
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split := strings.Split(val, "=")
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if len(split) != 2 {
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return environ, fmt.Errorf("Some weird env vars")
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}
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environ[split[0]] = split[1]
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}
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for key := range environ {
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if !(strings.HasSuffix(key, "_SERVICE_HOST") ||
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strings.HasSuffix(key, "_SERVICE_PORT")) {
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delete(environ, key)
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}
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}
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return environ, nil
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}
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func printInfo(resp http.ResponseWriter, req *http.Request) {
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kubeVars, err := getKubeEnv()
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if err != nil {
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http.Error(resp, err.Error(), http.StatusInternalServerError)
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return
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}
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backendHost := os.Getenv("BACKEND_SRV_SERVICE_HOST")
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backendPort := os.Getenv("BACKEND_SRV_SERVICE_PORT")
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backendRsp, backendErr := http.Get(fmt.Sprintf(
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"http://%v:%v/",
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backendHost,
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backendPort))
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if backendErr == nil {
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defer backendRsp.Body.Close()
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}
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name := os.Getenv("POD_NAME")
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namespace := os.Getenv("POD_NAMESPACE")
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fmt.Fprintf(resp, "Pod Name: %v \n", name)
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fmt.Fprintf(resp, "Pod Namespace: %v \n", namespace)
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envvar := os.Getenv("USER_VAR")
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fmt.Fprintf(resp, "USER_VAR: %v \n", envvar)
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fmt.Fprintf(resp, "\nKubenertes environment variables\n")
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var keys []string
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for key := range kubeVars {
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keys = append(keys, key)
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}
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sort.Strings(keys)
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for _, key := range keys {
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fmt.Fprintf(resp, "%v = %v \n", key, kubeVars[key])
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}
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fmt.Fprintf(resp, "\nFound backend ip: %v port: %v\n", backendHost, backendPort)
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if backendErr == nil {
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fmt.Fprintf(resp, "Response from backend\n")
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io.Copy(resp, backendRsp.Body)
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} else {
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fmt.Fprintf(resp, "Error from backend: %v", backendErr.Error())
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}
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}
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func main() {
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http.HandleFunc("/", printInfo)
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log.Fatal(http.ListenAndServe(":8080", nil))
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}
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