/
main.go
198 lines (161 loc) · 4.52 KB
/
main.go
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package main
import (
"bytes"
"encoding/base64"
"flag"
"fmt"
"github.com/kelseyhightower/envconfig"
"github.com/n3wscott/knap/pkg/config"
"github.com/n3wscott/knap/pkg/graph"
"html/template"
"image"
"image/jpeg"
"io/ioutil"
"k8s.io/client-go/dynamic"
"log"
"net/http"
"os"
"os/exec"
"os/user"
"path"
"path/filepath"
"strconv"
// Uncomment the following line to load the gcp plugin (only required to authenticate against GKE clusters).
_ "k8s.io/client-go/plugin/pkg/client/auth/gcp"
)
var (
cluster string
kubeconfig string
)
type envConfig struct {
// Namespace this pod exists in.
Namespace string `envconfig:"POD_NAMESPACE" required:"true"`
}
func init() {
flag.StringVar(&cluster, "cluster", "",
"Provide the cluster to test against. Defaults to the current cluster in kubeconfig.")
var defaultKubeconfig string
if usr, err := user.Current(); err == nil {
defaultKubeconfig = path.Join(usr.HomeDir, ".kube/config")
}
flag.StringVar(&kubeconfig, "kubeconfig", defaultKubeconfig,
"Provide the path to the `kubeconfig` file.")
}
var client dynamic.Interface
var env envConfig
func main() {
flag.Parse()
if err := envconfig.Process("", &env); err != nil {
log.Printf("[ERROR] Failed to process env var: %s", err)
os.Exit(1)
}
cfg, err := config.BuildClientConfig(kubeconfig, cluster)
if err != nil {
log.Fatalf("Error building kubeconfig", err)
}
client = dynamic.NewForConfigOrDie(cfg)
http.HandleFunc("/favicon.ico", favicon)
http.HandleFunc("/", handler)
log.Println("Listening on 8080")
log.Fatal(http.ListenAndServe(":8080", nil))
}
func favicon(w http.ResponseWriter, r *http.Request) {
img := image.NewRGBA(image.Rect(0, 0, 64, 64))
buffer := new(bytes.Buffer)
if err := jpeg.Encode(buffer, img, nil); err != nil {
log.Println("unable to encode image.")
}
writeBytes(w, buffer.Bytes(), "jpg")
}
func getQueryParam(r *http.Request, key string) string {
keys, ok := r.URL.Query()[key]
if !ok || len(keys[0]) < 1 {
return ""
}
return keys[0]
}
var defaultPage = "html" // or img
var defaultFormat = "svg" // or png
var defaultFocus = "trigger" // or png
func handler(w http.ResponseWriter, r *http.Request) {
page := getQueryParam(r, "page")
if page == "" {
page = defaultPage
}
format := getQueryParam(r, "format")
if format == "" {
format = defaultFormat
}
focus := getQueryParam(r, "focus")
if focus == "" {
focus = defaultFocus
}
var dotGraph string
switch focus {
case "sub", "subs", "subscription", "subscriptions":
dotGraph = graph.ForSubscriptions(client, env.Namespace)
case "broker", "trigger", "triggers":
fallthrough
default:
dotGraph = graph.ForTriggers(client, env.Namespace)
}
file, err := dotToImage(format, []byte(dotGraph))
if err != nil {
log.Printf("dotToImage error %s", err)
return
}
img, err := ioutil.ReadFile(file)
defer os.Remove(file) // clean up
if page == "html" {
writeBytesWithTemplate(w, img, format)
} else {
writeBytes(w, img, format)
}
}
var dot string
func dotToImage(format string, b []byte) (string, error) {
if dot == "" {
var err error
dot, err = exec.LookPath("dot")
if err != nil {
log.Fatalln("unable to find program 'dot', please install it or check your PATH")
}
}
var img = filepath.Join(os.TempDir(), fmt.Sprintf("graph.%s", format))
cmd := exec.Command(dot, fmt.Sprintf("-T%s", format), "-o", img) //, tmpfile.Name())
cmd.Stdin = bytes.NewBuffer(b)
if err := cmd.Run(); err != nil {
return "", err
}
return img, nil
}
var Template = `<!DOCTYPE html>
<html lang="en"><head></head>
<body><img src="data:{{.Format}},{{.Image}}"></body>`
func writeBytesWithTemplate(w http.ResponseWriter, b []byte, format string) {
if format == "svg" {
_, _ = w.Write([]byte(`<!DOCTYPE html><html lang="en"><head></head><body>`))
_, _ = w.Write(b)
_, _ = w.Write([]byte(`</body></html>`))
return
}
data := map[string]interface{}{
"Image": base64.StdEncoding.EncodeToString(b),
"Format": fmt.Sprintf("image/%s;base64", format),
}
if tmpl, err := template.New("image").Parse(Template); err != nil {
log.Println("unable to parse image template.")
} else {
if err = tmpl.Execute(w, data); err != nil {
log.Println("unable to execute template.")
}
}
}
// writeImage encodes an image 'img' in jpeg format and writes it into ResponseWriter.
func writeBytes(w http.ResponseWriter, b []byte, format string) {
w.Header().Set("Content-Type", "image/"+format)
w.Header().Set("Content-Length", strconv.Itoa(len(b)))
if _, err := w.Write(b); err != nil {
log.Println("unable to write image.")
}
}