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configmap-reload.go
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configmap-reload.go
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package main
import (
"bytes"
"flag"
"fmt"
"io/ioutil"
"log"
"net/http"
"net/url"
"os"
"path/filepath"
"strconv"
"strings"
"text/template"
"time"
fsnotify "github.com/fsnotify/fsnotify"
"github.com/getoutreach/configmap-reload/pkg/filepathext"
"github.com/prometheus/client_golang/prometheus"
"github.com/prometheus/client_golang/prometheus/promhttp"
"gopkg.in/yaml.v2"
)
const namespace = "configmap_reload"
var (
volumeDirs volumeDirsFlag
webhook webhookFlag
webhookMethod = flag.String("webhook-method", "POST", "the HTTP method url to use to send the webhook")
webhookStatusCode = flag.Int("webhook-status-code", 200, "the HTTP status code indicating successful triggering of reload")
listenAddress = flag.String("web.listen-address", ":9533", "Address to listen on for web interface and telemetry.")
metricPath = flag.String("web.telemetry-path", "/metrics", "Path under which to expose metrics.")
secretPath = flag.String("secret-path", "", "YAML file containing to be passed as go-template values")
templateFile = flag.String("template-file", "", "Template file to render, relative to the volume dir")
outputVolumeDir = flag.String("output-dir", "", "Output directory for processed templates")
useEnv = flag.Bool("use-env", false, "When set to true, will use env vars instead of a secret file")
lastReloadError = prometheus.NewGaugeVec(prometheus.GaugeOpts{
Namespace: namespace,
Name: "last_reload_error",
Help: "Whether the last reload resulted in an error (1 for error, 0 for success)",
}, []string{"webhook"})
requestDuration = prometheus.NewGaugeVec(prometheus.GaugeOpts{
Namespace: namespace,
Name: "last_request_duration_seconds",
Help: "Duration of last webhook request",
}, []string{"webhook"})
successReloads = prometheus.NewCounterVec(prometheus.CounterOpts{
Namespace: namespace,
Name: "success_reloads_total",
Help: "Total success reload calls",
}, []string{"webhook"})
requestErrorsByReason = prometheus.NewCounterVec(prometheus.CounterOpts{
Namespace: namespace,
Name: "request_errors_total",
Help: "Total request errors by reason",
}, []string{"webhook", "reason"})
watcherErrors = prometheus.NewCounter(prometheus.CounterOpts{
Namespace: namespace,
Name: "watcher_errors_total",
Help: "Total filesystem watcher errors",
})
requestsByStatusCode = prometheus.NewCounterVec(prometheus.CounterOpts{
Namespace: namespace,
Name: "requests_total",
Help: "Total requests by response status code",
}, []string{"webhook", "status_code"})
)
// Secret is an interface to secret providers
type Secret interface {
Get() (interface{}, error)
}
// YAMLFileSecret is a YAML file secret interface
type YAMLFileSecret struct {
file string
}
// NewYAMLFileSecret returns a new yaml file backed secret interface
func NewYAMLFileSecret(file string) *YAMLFileSecret {
return &YAMLFileSecret{file: file}
}
// Get returns an interface{} of the contents of a yaml file
func (y *YAMLFileSecret) Get() (interface{}, error) {
var inf interface{}
b, err := ioutil.ReadFile(y.file)
if err != nil {
return "", fmt.Errorf("failed to read secret file: %v", err)
}
if err := yaml.Unmarshal(b, &inf); err != nil {
return "", fmt.Errorf("failed to unmarshall secret file: %v", err)
}
return inf, nil
}
// EnvSecret is a env secret interface
type EnvSecret struct{}
// NewEnvSecret returns a new env backed secret interface
// env should be the same format as os.Environ
func NewEnvSecret(env []string) *EnvSecret {
return &EnvSecret{}
}
// Get returns a map[string]string of key value pair of the env vars
func (e *EnvSecret) Get() (interface{}, error) {
keys := make(map[string]string)
for _, v := range os.Environ() {
splits := strings.SplitN(v, "=", 2)
// set KEY=VALUE supporting = in value
keys[splits[0]] = splits[1]
}
return keys, nil
}
func init() {
prometheus.MustRegister(lastReloadError)
prometheus.MustRegister(requestDuration)
prometheus.MustRegister(successReloads)
prometheus.MustRegister(requestErrorsByReason)
prometheus.MustRegister(watcherErrors)
prometheus.MustRegister(requestsByStatusCode)
}
// generateNewConf returns a fully rendered configuration file with support
// for golang templating
func generateNewConf(volumeDir, secretPath string, info os.FileInfo, templatePath string) (string, error) {
rel, err := filepath.Rel(volumeDir, templatePath)
if err != nil {
return "", err
}
b, err := ioutil.ReadFile(templatePath)
if err != nil {
return "", fmt.Errorf("failed to read file: %v", err)
}
// if it's not the template file we want, then we just return the raw contents
// this also doubles as not running without a template file being set.
if rel != *templateFile {
return string(b), nil
}
log.Printf("rendering file '%s'", templatePath)
t := template.New("conf")
tmpl, err := t.Parse(string(b))
if err != nil {
return "", fmt.Errorf("failed to create template: %v", err)
}
var secret Secret
if *useEnv {
secret = NewEnvSecret(os.Environ())
} else {
secret = NewYAMLFileSecret(secretPath)
}
inf, err := secret.Get()
if err != nil {
return "", fmt.Errorf("failed to get secret information: %v", err)
}
var resp bytes.Buffer
if err := tmpl.Execute(&resp, inf); err != nil {
return "", fmt.Errorf("failed to render template: %v", err)
}
return resp.String(), nil
}
// renderConfigs renders all configuration files
func renderConfigs(outputVolumeDir, volumeDir, secretPath string) error {
f, err := ioutil.ReadDir(outputVolumeDir)
if err != nil {
return fmt.Errorf("failed to read outputVolumeDir: %v", err)
}
for _, o := range f {
absPath := filepath.Join(outputVolumeDir, o.Name())
log.Println("cleaning up output dir", absPath)
err := os.RemoveAll(absPath)
if err != nil {
log.Printf("WARN: failed to cleanup outputVolumeDir: %v", err)
}
}
err = filepathext.SymWalk(volumeDir, func(path string, info os.FileInfo, err error) error {
// failed to access the file, or some other unworkaroundable error
if err != nil {
return fmt.Errorf("walk err: %s", err)
}
if info.IsDir() {
log.Printf("walking into dir '%s'", info.Name())
return nil
}
s, err := generateNewConf(volumeDir, secretPath, info, path)
if err != nil {
return err
}
rel, err := filepath.Rel(volumeDir, path)
if err != nil {
return err
}
savePath := filepath.Join(outputVolumeDir, rel)
log.Printf("write '%s' -> '%s'", path, savePath)
if err := os.MkdirAll(filepath.Dir(savePath), 0777); err != nil {
return fmt.Errorf("failed to mkdir for savepath: %v", err)
}
err = ioutil.WriteFile(savePath, []byte(s), info.Mode())
return err
})
return err
}
func main() {
flag.Var(&volumeDirs, "volume-dir", "the config map volume directory to watch for updates; may be used multiple times")
flag.Var(&webhook, "webhook-url", "the url to send a request to when the specified config map volume directory has been updated")
flag.Parse()
if len(volumeDirs) < 1 {
log.Println("Missing volume-dir")
log.Println()
flag.Usage()
os.Exit(1)
}
if len(webhook) < 1 {
log.Println("Missing webhook-url")
log.Println()
flag.Usage()
os.Exit(1)
}
// why template without secrets?
if *templateFile != "" && *secretPath == "" && !*useEnv {
log.Println("secretPath must be set when using templateFile")
log.Println()
flag.Usage()
os.Exit(1)
}
if *secretPath != "" && *useEnv {
log.Println("secretPath can't be set when useEnv is set")
log.Println()
flag.Usage()
os.Exit(1)
}
// only support output volumes in templateFile mode
if *outputVolumeDir != "" && *templateFile == "" {
log.Println("outputVolumeDir is only support when in templating mode")
log.Println()
flag.Usage()
os.Exit(1)
}
// can only output to one dir, so only support one dir
if *outputVolumeDir != "" && len(volumeDirs) > 1 {
log.Println("only one volumeDir can be set when outputVolumeDir is set")
log.Println()
flag.Usage()
os.Exit(1)
}
watcher, err := fsnotify.NewWatcher()
if err != nil {
log.Fatal(err)
}
defer watcher.Close()
if *outputVolumeDir != "" {
if err := os.MkdirAll(*outputVolumeDir, 0777); err != nil {
log.Fatalf("failed to ensure outputVolumeDir existed: %v", err)
}
}
if err := renderConfigs(*outputVolumeDir, volumeDirs[0], *secretPath); err != nil {
log.Fatalf("failed to render configs: %v", err)
}
go func() {
for {
select {
case event := <-watcher.Events:
if !isValidEvent(event) {
log.Printf("skipping invalid event: %v", event)
continue
}
log.Println("config map updated")
err := renderConfigs(*outputVolumeDir, volumeDirs[0], *secretPath)
if err != nil {
log.Printf("ERROR: failed to render configuration: %v", err)
continue
}
for _, h := range webhook {
begun := time.Now()
req, err := http.NewRequest(*webhookMethod, h.String(), nil)
if err != nil {
setFailureMetrics(h.String(), "client_request_create")
log.Println("error:", err)
continue
}
userInfo := h.User
if userInfo != nil {
if password, passwordSet := userInfo.Password(); passwordSet {
req.SetBasicAuth(userInfo.Username(), password)
}
}
resp, err := http.DefaultClient.Do(req)
if err != nil {
setFailureMetrics(h.String(), "client_request_do")
log.Println("error:", err)
continue
}
resp.Body.Close()
requestsByStatusCode.WithLabelValues(h.String(), strconv.Itoa(resp.StatusCode)).Inc()
if resp.StatusCode != *webhookStatusCode {
setFailureMetrics(h.String(), "client_response")
log.Println("error:", "Received response code", resp.StatusCode, ", expected", *webhookStatusCode)
continue
}
setSuccessMetrics(h.String(), begun)
log.Println("successfully triggered reload")
}
case err := <-watcher.Errors:
watcherErrors.Inc()
log.Println("error:", err)
}
}
}()
for _, d := range volumeDirs {
log.Printf("Watching directory: '%s'", d)
if err = watcher.Add(d); err != nil {
log.Fatal(err)
}
}
log.Fatal(serverMetrics(*listenAddress, *metricPath))
}
func setFailureMetrics(h, reason string) {
requestErrorsByReason.WithLabelValues(h, reason).Inc()
lastReloadError.WithLabelValues(h).Set(1.0)
}
func setSuccessMetrics(h string, begun time.Time) {
requestDuration.WithLabelValues(h).Set(time.Since(begun).Seconds())
successReloads.WithLabelValues(h).Inc()
lastReloadError.WithLabelValues(h).Set(0.0)
}
func isValidEvent(event fsnotify.Event) bool {
// for testing, have this return true
// return true
if event.Op&fsnotify.Create != fsnotify.Create {
return false
}
if filepath.Base(event.Name) != "..data" {
return false
}
return true
}
func serverMetrics(listenAddress, metricsPath string) error {
http.Handle(metricsPath, promhttp.Handler())
http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
w.Write([]byte(`
<html>
<head><title>ConfigMap Reload Metrics</title></head>
<body>
<h1>ConfigMap Reload</h1>
<p><a href='` + metricsPath + `'>Metrics</a></p>
</body>
</html>
`))
})
return http.ListenAndServe(listenAddress, nil)
}
type volumeDirsFlag []string
type webhookFlag []*url.URL
func (v *volumeDirsFlag) Set(value string) error {
*v = append(*v, value)
return nil
}
func (v *volumeDirsFlag) String() string {
return fmt.Sprint(*v)
}
func (v *webhookFlag) Set(value string) error {
u, err := url.Parse(value)
if err != nil {
return fmt.Errorf("invalid URL: %v", err)
}
*v = append(*v, u)
return nil
}
func (v *webhookFlag) String() string {
return fmt.Sprint(*v)
}