Merge pull request #394 from xiekeyang/feature-panic-hook

Feature: Add Hook for Web Application Panic

cmd/registry/config.yml

@@ -4,6 +4,20 @@ log:
   fields:
     service: registry
     environment: development
+  hooks:
+    - type: mail
+      disabled: true
+      levels:
+        - panic
+      options:
+        smtp:
+          addr: mail.example.com:25
+          username: mailuser
+          password: password
+          insecure: true
+        from: sender@example.com
+        to:
+          - errors@example.com
 storage:
     cache:
         blobdescriptor: redis

configuration/configuration.go

@@ -29,6 +29,10 @@ type Configuration struct {
 		// Fields allows users to specify static string fields to include in
 		// the logger context.
 		Fields map[string]interface{} `yaml:"fields,omitempty"`
+
+		// Hooks allows users to configurate the log hooks, to enabling the
+		// sequent handling behavior, when defined levels of log message emit.
+		Hooks []LogHook `yaml:"hooks,omitempty"`
 	}
 
 	// Loglevel is the level at which registry operations are logged. This is
@@ -126,6 +130,47 @@ type Configuration struct {
 	} `yaml:"redis,omitempty"`
 }
 
+// LogHook is composed of hook Level and Type.
+// After hooks configuration, it can execute the next handling automatically,
+// when defined levels of log message emitted.
+// Example: hook can sending an email notification when error log happens in app.
+type LogHook struct {
+	// Disable lets user select to enable hook or not.
+	Disabled bool `yaml:"disabled,omitempty"`
+
+	// Type allows user to select which type of hook handler they want.
+	Type string `yaml:"type,omitempty"`
+
+	// Levels set which levels of log message will let hook executed.
+	Levels []string `yaml:"levels,omitempty"`
+
+	// MailOptions allows user to configurate email parameters.
+	MailOptions MailOptions `yaml:"options,omitempty"`
+}
+
+// MailOptions provides the configuration sections to user, for specific handler.
+type MailOptions struct {
+	SMTP struct {
+		// Addr defines smtp host address
+		Addr string `yaml:"addr,omitempty"`
+
+		// Username defines user name to smtp host
+		Username string `yaml:"username,omitempty"`
+
+		// Password defines password of login user
+		Password string `yaml:"password,omitempty"`
+
+		// Insecure defines if smtp login skips the secure cerification.
+		Insecure bool `yaml:"insecure,omitempty"`
+	} `yaml:"smtp,omitempty"`
+
+	// From defines mail sending address
+	From string `yaml:"from,omitempty"`
+
+	// To defines mail receiving address
+	To []string `yaml:"to,omitempty"`
+}
+
 // v0_1Configuration is a Version 0.1 Configuration struct
 // This is currently aliased to Configuration, as it is the current version
 type v0_1Configuration Configuration

configuration/configuration_test.go

@@ -20,6 +20,7 @@ var configStruct = Configuration{
 		Level     Loglevel               `yaml:"level"`
 		Formatter string                 `yaml:"formatter,omitempty"`
 		Fields    map[string]interface{} `yaml:"fields,omitempty"`
+		Hooks     []LogHook              `yaml:"hooks,omitempty"`
 	}{
 		Fields: map[string]interface{}{"environment": "test"},
 	},

docs/configuration.md

@@ -25,6 +25,20 @@ log:
 	fields:
 		service: registry
 		environment: staging
+	hooks:
+		- type: mail
+		  disabled: true
+		  levels:
+			- panic
+		  options:
+			smtp:
+				addr: mail.example.com:25
+				username: mailuser
+				password: password
+				insecure: true
+			from: sender@example.com
+			to: 
+				- errors@example.com
 loglevel: debug # deprecated: use "log"
 storage:
 	filesystem:
@@ -233,6 +247,28 @@ log:
     </td>
 </table>
 
+## hooks
+
+
+```yaml 
+hooks:
+  - type: mail
+    levels:
+      - panic
+    options:
+      smtp:
+        addr: smtp.sendhost.com:25
+        username: sendername
+        password: password
+        insecure: true
+      from: name@sendhost.com
+      to:
+        - name@receivehost.com
+```
+
+The `hooks` subsection configures the logging hooks' behavior. This subsection
+includes a sequence handler which you can use for sending mail, for example.
+Refer to `loglevel` to configure the level of messages printed.
 
 ## loglevel
 

registry/handlers/app.go

@@ -9,6 +9,7 @@ import (
 	"os"
 	"time"
 
+	log "github.com/Sirupsen/logrus"
 	"github.com/docker/distribution"
 	"github.com/docker/distribution/configuration"
 	ctxu "github.com/docker/distribution/context"
@@ -101,6 +102,7 @@ func NewApp(ctx context.Context, configuration configuration.Configuration) *App
 
 	app.configureEvents(&configuration)
 	app.configureRedis(&configuration)
+	app.configureLogHook(&configuration)
 
 	// configure storage caches
 	if cc, ok := configuration.Storage["cache"]; ok {
@@ -291,6 +293,31 @@ func (app *App) configureRedis(configuration *configuration.Configuration) {
 	}))
 }
 
+// configureLogHook prepares logging hook parameters.
+func (app *App) configureLogHook(configuration *configuration.Configuration) {
+	logger := ctxu.GetLogger(app).(*log.Entry).Logger
+	for _, configHook := range configuration.Log.Hooks {
+		if !configHook.Disabled {
+			switch configHook.Type {
+			case "mail":
+				hook := &logHook{}
+				hook.LevelsParam = configHook.Levels
+				hook.Mail = &mailer{
+					Addr:     configHook.MailOptions.SMTP.Addr,
+					Username: configHook.MailOptions.SMTP.Username,
+					Password: configHook.MailOptions.SMTP.Password,
+					Insecure: configHook.MailOptions.SMTP.Insecure,
+					From:     configHook.MailOptions.From,
+					To:       configHook.MailOptions.To,
+				}
+				logger.Hooks.Add(hook)
+			default:
+			}
+		}
+	}
+	app.Context = ctxu.WithLogger(app.Context, logger)
+}
+
 func (app *App) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	defer r.Body.Close() // ensure that request body is always closed.
 

registry/handlers/hooks.go

@@ -0,0 +1,53 @@
+package handlers
+
+import (
+	"bytes"
+	"errors"
+	"fmt"
+	"strings"
+	"text/template"
+
+	"github.com/Sirupsen/logrus"
+)
+
+// logHook is for hooking Panic in web application
+type logHook struct {
+	LevelsParam []string
+	Mail        *mailer
+}
+
+// Fire forwards an error to LogHook
+func (hook *logHook) Fire(entry *logrus.Entry) error {
+	addr := strings.Split(hook.Mail.Addr, ":")
+	if len(addr) != 2 {
+		return errors.New("Invalid Mail Address")
+	}
+	host := addr[0]
+	subject := fmt.Sprintf("[%s] %s: %s", entry.Level, host, entry.Message)
+
+	html := `
+	{{.Message}}
+
+	{{range $key, $value := .Data}}
+	{{$key}}: {{$value}}
+	{{end}}
+	`
+	b := bytes.NewBuffer(make([]byte, 0))
+	t := template.Must(template.New("mail body").Parse(html))
+	if err := t.Execute(b, entry); err != nil {
+		return err
+	}
+	body := fmt.Sprintf("%s", b)
+
+	return hook.Mail.sendMail(subject, body)
+}
+
+// Levels contains hook levels to be catched
+func (hook *logHook) Levels() []logrus.Level {
+	levels := []logrus.Level{}
+	for _, v := range hook.LevelsParam {
+		lv, _ := logrus.ParseLevel(v)
+		levels = append(levels, lv)
+	}
+	return levels
+}

registry/handlers/mail.go

@@ -0,0 +1,45 @@
+package handlers
+
+import (
+	"errors"
+	"net/smtp"
+	"strings"
+)
+
+// mailer provides fields of email configuration for sending.
+type mailer struct {
+	Addr, Username, Password, From string
+	Insecure                       bool
+	To                             []string
+}
+
+// sendMail allows users to send email, only if mail parameters is configured correctly.
+func (mail *mailer) sendMail(subject, message string) error {
+	addr := strings.Split(mail.Addr, ":")
+	if len(addr) != 2 {
+		return errors.New("Invalid Mail Address")
+	}
+	host := addr[0]
+	msg := []byte("To:" + strings.Join(mail.To, ";") +
+		"\r\nFrom: " + mail.From +
+		"\r\nSubject: " + subject +
+		"\r\nContent-Type: text/plain\r\n\r\n" +
+		message)
+	auth := smtp.PlainAuth(
+		"",
+		mail.Username,
+		mail.Password,
+		host,
+	)
+	err := smtp.SendMail(
+		mail.Addr,
+		auth,
+		mail.From,
+		mail.To,
+		[]byte(msg),
+	)
+	if err != nil {
+		return err
+	}
+	return nil
+}