Kubernetes ImagePolicyWebhook与ValidatingAdmissionWebhook【4】main.go源码解析（1）

import (
  "fmt"  //打印输出
  "os"  //系统管理
  "strings"  //字符串管理
  "github.com/labstack/echo"  //可扩展，轻量级的web框架
  "github.com/labstack/echo/middleware"  //echo web框架中间件
  "github.com/labstack/gommon/log"  //自定义的日志输出
  "gopkg.in/urfave/cli.v1"   //用于在 Go 中构建命令行应用程序
  "github.com/kainlite/kube-image-bouncer/handlers"
)

func main() {
//定义参数
  var cert, key, whitelist string  //证书，密钥，白名单
  var port int  //webhook的端口
  var debug bool //debug模式
//定义命令对象
  app := cli.NewApp()
  app.Name = "kube-image-bouncer"
  app.Usage = "webhook endpoint for kube image policy admission controller"
//定义命令参数
  app.Flags = []cli.Flag{
    cli.StringFlag{
      Name:        "cert, c",
      Usage:       "Path to the certificate to use",
      EnvVar:      "BOUNCER_CERTIFICATE",
      Destination: &cert,
    },
    cli.StringFlag{
      Name:        "key, k",
      Usage:       "Path to the key to use",
      EnvVar:      "BOUNCER_KEY",
      Destination: &key,
    },
    cli.StringFlag{
      Name:        "registry-whitelist",
      Usage:       "Comma separated list of accepted registries",
      EnvVar:      "BOUNCER_REGISTRY_WHITELIST",
      Destination: &whitelist,
    },
    cli.IntFlag{
      Name:        "port, p",
      Value:       1323,
      Usage:       "Port to listen to",
      EnvVar:      "BOUNCER_PORT",
      Destination: &port,
    },
    cli.BoolFlag{
      Name:        "debug",
      Usage:       "Enable extra debugging",
      EnvVar:      "BOUNCER_DEBUG",
      Destination: &debug,
    },
  }
//定义命令的调用方式
  app.Action = func(c *cli.Context) error {
    e := echo.New()
    e.POST("/image_policy", handlers.PostImagePolicy())
    e.POST("/", handlers.PostValidatingAdmission())
    e.Use(middleware.LoggerWithConfig(middleware.LoggerConfig{
      Format: "method=${method}, uri=${uri}, status=${status}\n",
    }))
    if debug {
      e.Logger.SetLevel(log.DEBUG)
    }
    if whitelist != "" {
      handlers.RegistryWhitelist = strings.Split(whitelist, ",")
      fmt.Printf(
        "Accepting only images from these registries: %+v\n",
        handlers.RegistryWhitelist)
      fmt.Println("WARN: this feature is implemented only by the ValidatingAdmissionWebhook code")
    } else {
      fmt.Println("WARN: accepting images from ALL registries")
    }
    var err error
    if cert != "" && key != "" {
      err = e.StartTLS(fmt.Sprintf(":%d", port), cert, key)
    } else {
      err = e.Start(fmt.Sprintf(":%d", port))
    }
    if err != nil {
      return cli.NewExitError(err, 1)
    }
    return nil
  }
//运行app对象
  app.Run(os.Args)
}

type (
  // LoggerConfig defines the config for Logger middleware.
  LoggerConfig struct {
    // Skipper defines a function to skip middleware.
    Skipper Skipper
    Format string `yaml:"format"`
    // Optional. Default value DefaultLoggerConfig.CustomTimeFormat.
    CustomTimeFormat string `yaml:"custom_time_format"`
    // Output is a writer where logs in JSON format are written.
    // Optional. Default value os.Stdout.
    Output io.Writer
    template *fasttemplate.Template
    colorer  *color.Color
    pool     *sync.Pool
  }
)
var (
  // DefaultLoggerConfig is the default Logger middleware config.
  DefaultLoggerConfig = LoggerConfig{
    Skipper: DefaultSkipper,
    Format: `{"time":"${time_rfc3339_nano}","id":"${id}","remote_ip":"${remote_ip}",` +
      `"host":"${host}","method":"${method}","uri":"${uri}","user_agent":"${user_agent}",` +
      `"status":${status},"error":"${error}","latency":${latency},"latency_human":"${latency_human}"` +
      `,"bytes_in":${bytes_in},"bytes_out":${bytes_out}}` + "\n",
    CustomTimeFormat: "2006-01-02 15:04:05.00000",
    colorer:          color.New(),
  }
)
// LoggerWithConfig returns a Logger middleware with config.
// See: `Logger()`.
func LoggerWithConfig(config LoggerConfig) echo.MiddlewareFunc {
  // Defaults
  if config.Skipper == nil {
    config.Skipper = DefaultLoggerConfig.Skipper
  }
  if config.Format == "" {
    config.Format = DefaultLoggerConfig.Format
  }
  if config.Output == nil {
    config.Output = DefaultLoggerConfig.Output
  }
  config.template = fasttemplate.New(config.Format, "${", "}")
  config.colorer = color.New()
  config.colorer.SetOutput(config.Output)
  config.pool = &sync.Pool{
    New: func() interface{} {
      return bytes.NewBuffer(make([]byte, 256))
    },
  }

type Context interface {
  Request() *http.Request
  SetRequest(r *http.Request)
  Response() *Response
  IsTLS() bool
  IsWebSocket() bool
  Scheme() string
  RealIP() string
  Path() string
  SetPath(p string)
  Param(name string) string
  ParamNames() []string
  SetParamNames(names ...string)
  ParamValues() []string
  SetParamValues(values ...string)
  QueryParam(name string) string
  QueryParams() url.Values
  QueryString() string
  FormValue(name string) string
  FormParams() (url.Values, error)
  FormFile(name string) (*multipart.FileHeader, error)
  MultipartForm() (*multipart.Form, error)
  Cookie(name string) (*http.Cookie, error)
  SetCookie(cookie *http.Cookie)
  Cookies() []*http.Cookie
  Get(key string) interface{}
  Set(key string, val interface{})
  Bind(i interface{}) error
  Validate(i interface{}) error
  Render(code int, name string, data interface{}) error
  HTML(code int, html string) error
  HTMLBlob(code int, b []byte) error
  String(code int, s string) error
  JSON(code int, i interface{}) error
  JSONPretty(code int, i interface{}, indent string) error
  JSONBlob(code int, b []byte) error
  JSONP(code int, callback string, i interface{}) error
  JSONPBlob(code int, callback string, b []byte) error
  XML(code int, i interface{}) error
  XMLPretty(code int, i interface{}, indent string) error
  XMLBlob(code int, b []byte) error
  Blob(code int, contentType string, b []byte) error
  Stream(code int, contentType string, r io.Reader) error
  File(file string) error
  Attachment(file string, name string) error
  Inline(file string, name string) error
  NoContent(code int) error
  Redirect(code int, url string) error
  Error(err error)
  Handler() HandlerFunc
  SetHandler(h HandlerFunc)
  Logger() Logger
  Echo() *Echo
  Reset(r *http.Request, w http.ResponseWriter)
}