/
main.go
223 lines (199 loc) · 6.01 KB
/
main.go
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package main
import (
"encoding/json"
"errors"
"fmt"
"html"
"io"
"math/rand"
"net/http"
"os"
"strings"
"time"
"cloud.google.com/go/compute/metadata"
"github.com/enescakir/emoji"
)
type Payload struct {
ClusterName string `json:"cluster_name,omitempty"`
InstanceId string `json:"gce_instance_id,omitempty"`
ServiceAccount string `json:"gce_service_account,omitempty"`
Headers map[string][]string `json:"headers,omitempty"`
HostHeader string `json:"host_header,omitempty"`
Metadata string `json:"metadata,omitempty"`
NodeName string `json:"node_name,omitempty"`
PodIp string `json:"pod_ip,omitempty"`
PodName string `json:"pod_name"`
PodNameEmoji string `json:"pod_name_emoji"`
PodNamespace string `json:"pod_namespace,omitempty"`
PodServiceAccount string `json:"pod_service_account,omitempty"`
ProjectId string `json:"project_id,omitempty"`
Timestamp string `json:"timestamp"`
Zone string `json:"zone,omitempty"`
BackendResult map[string]interface{} `json:"backend_result,omitempty"`
}
// laziness and creating a global payload
var payload Payload
// headers to propagate
var headersToPropagate = []string{
"x-request-id",
"x-b3-traceid",
"x-b3-spanid",
"x-b3-parentspanid",
"x-b3-sampled",
"x-b3-flags",
"x-ot-span-context",
"x-cloud-trace-context",
"traceparent",
"grpc-trace-bin",
}
// pick a random value from a map (used for emoji assignment)
// using https://programming-idioms.org/idiom/250/pick-a-random-value-from-a-map/4435/go
func pick(m map[string]string) string {
k := rand.Intn(len(m))
for _, x := range m {
if k == 0 {
return x
}
k--
}
panic("unreachable")
}
// test comment
func generatePayload() Payload {
//p := Payload{}
payload.PodName, _ = os.Hostname()
payload.Timestamp = time.Now().UTC().String()
payload.PodNameEmoji = pick(emoji.Map())
//gceMetadataClient := metadata.NewClient(&http.Client{})
//projectId, gceErr := gceMetadataClient.ProjectID()
projectId, gceErr := metadata.ProjectID()
//fmt.Printf(projectId + "\n")
if gceErr != nil {
fmt.Println("Unable to capture GCE metadata")
} else {
payload.ProjectId = projectId
payload.Zone, _ = metadata.Zone()
payload.InstanceId, _ = metadata.InstanceID()
payload.ServiceAccount, _ = metadata.Email("default")
payload.ClusterName, _ = metadata.InstanceAttributeValue("cluster-name")
}
// deal with K8s downward API stuff
if len(getEnv("NODE_NAME", "")) > 0 {
payload.NodeName = getEnv("NODE_NAME", "")
}
if len(getEnv("POD_NAMESPACE", "")) > 0 {
payload.PodNamespace = getEnv("POD_NAMESPACE", "")
}
if len(getEnv("POD_IP", "")) > 0 {
payload.PodIp = getEnv("POD_IP", "")
}
if len(getEnv("POD_SERVICE_ACCOUNT", "")) > 0 {
payload.PodServiceAccount = getEnv("POD_SERVICE_ACCOUNT", "")
}
if len(getEnv("METADATA", "")) > 0 {
payload.Metadata = getEnv("METADATA", "")
}
return payload
}
func getEnv(key, fallback string) string {
if value, ok := os.LookupEnv(key); ok {
return value
}
// else condition
fmt.Printf("Environment variable %s not found\n", key)
return fallback
}
func contains(s []string, str string) bool {
for _, v := range s {
// using EqualFold to make string comparison case-insensitive
if strings.EqualFold(v, str) {
return true
}
}
return false
}
func getRoot(w http.ResponseWriter, r *http.Request) {
fmt.Printf("got / request\n")
// update timestamp
payload.Timestamp = time.Now().UTC().String()
// get host header
payload.HostHeader = r.Host
// should we echo back incoming headers?
if getEnv("ECHO_HEADERS", "") == "True" {
payload.Headers = r.Header
}
// check for backend service call
if getEnv("BACKEND_ENABLED", "") == "True" {
if backendUrl, ok := os.LookupEnv("BACKEND_SERVICE"); ok {
client := &http.Client{}
req, err := http.NewRequest("GET", backendUrl, nil)
if err != nil {
panic(err)
}
// populate headers to request
/*for _, k := range headersToPropagate {
if r.Header.Values(k) {
req.Header.Add(k, v)
}
}*/
for k, v := range r.Header {
//fmt.Printf("checking %s %s\n", k, v)
//fmt.Printf("test\n")
if contains(headersToPropagate, k) {
//req.Header.Add(k, r.Header.Values(k))
for _, vOther := range v {
req.Header.Add(k, vOther)
//fmt.Printf("%s %s\n", k, vOther)
}
}
}
resp, err := client.Do(req)
if err != nil {
fmt.Printf("Call to %s failed", backendUrl)
defer resp.Body.Close()
} else {
defer resp.Body.Close()
body, err := io.ReadAll(resp.Body)
if err != nil {
fmt.Printf("Invalid response from %s", backendUrl)
} else {
var jsonRes map[string]interface{}
err = json.Unmarshal(body, &jsonRes)
if err != nil {
fmt.Printf("Unable to unmarshal response from %s", backendUrl)
} else {
payload.BackendResult = jsonRes
}
//payload.BackendResult = jsonRes.Marshal()
//marRes, _ := json.Marshal(jsonRes)
//fmt.Println(string(marRes))
}
}
}
}
//p, _ := json.Marshal(&generatePayload())
w.Header().Set("Content-Type", "application/json")
/*p, err := json.Marshal(Payload{PodName: "test", Timestamp: "test2"})
if err != nil {
fmt.Printf("Error: %s", err)
return
}
io.WriteString(w, string(p))*/
json.NewEncoder(w).Encode(payload)
}
func main() {
// initialize payload and hack to wait for WI to come online
time.Sleep(5 * time.Second)
payload = generatePayload()
http.HandleFunc("/healthz", func(w http.ResponseWriter, r *http.Request) {
fmt.Fprintf(w, "Hello, %q", html.EscapeString(r.URL.Path))
})
http.HandleFunc("/", getRoot)
err := http.ListenAndServe(":"+getEnv("PORT", "8080"), nil)
if errors.Is(err, http.ErrServerClosed) {
fmt.Printf("server closed\n")
} else if err != nil {
fmt.Printf("error starting server: %s\n", err)
os.Exit(1)
}
}