Recovery

The Recovery middleware is preset by the Hertz framework to provide the feature of Panic recovery for the Hertz framework.

The Recovery middleware is preset by the Hertz framework. The server.Default() will register Recovery middleware by default to provide the feature of Panic recovery for the Hertz framework.

If you don’t use server.Default(), you can also register the Recovery middleware as followings:

h := server.New()
h.Use(recovery.Recovery())

The Recovery middleware will recover any panics in the Hertz framework. When a panic occurs, the Recover middleware will print out the panic time, content and stack information by default, then set the status code as 500 through *app.RequestContext'.

Import

import "github.com/cloudwego/hertz/pkg/app/middlewares/server/recovery"

Example

package main

import (
	"context"
	"fmt"
	"net/http"
	"time"

	"github.com/cloudwego/hertz/pkg/app"
	"github.com/cloudwego/hertz/pkg/app/server"
)

func main() {
	h := server.Default(server.WithHostPorts(":8080"))
	h.GET("/test", func(ctx context.Context, c *app.RequestContext) {
		panic("test")
		c.String(http.StatusOK, "test interface")
	})
	h.Spin()
}

Configuration

The Recovery middleware provides a default panic recovery handlerdefaultRecoveryHandler()

You can also use the WithRecoveryHandler() function to customize the handler function when the panic occurs. The function signature is as follows:

func WithRecoveryHandler(f func(c context.Context, ctx *app.RequestContext, err interface{}, stack []byte))

For example, if you attempt to obtain client agent, you can customize your handler function as follows:

package main

import (
	"context"
	"fmt"
	"github.com/cloudwego/hertz/pkg/app/middlewares/server/recovery"
	"github.com/cloudwego/hertz/pkg/common/hlog"
	"github.com/cloudwego/hertz/pkg/protocol/consts"
	"net/http"
	"time"

	"github.com/cloudwego/hertz/pkg/app"
	"github.com/cloudwego/hertz/pkg/app/server"
)

func MyRecoveryHandler(c context.Context, ctx *app.RequestContext, err interface{}, stack []byte) {
	hlog.SystemLogger().CtxErrorf(c, "[Recovery] err=%v\nstack=%s", err, stack)
	hlog.SystemLogger().Infof("Client: %s", ctx.Request.Header.UserAgent())
	ctx.AbortWithStatus(consts.StatusInternalServerError)
}

func main() {
	h := server.New()
	h.Use(recovery.Recovery(recovery.WithRecoveryHandler(MyRecoveryHandler)))
	h.GET("/ping", func(ctx context.Context, c *app.RequestContext) {
		panic("test")
		c.String(http.StatusOK, "pong "+fmt.Sprint(time.Now().Unix()))
	})
	h.Spin()
}

Last modified June 26, 2024 : doc: add construct use case (#1098) (83b7cf9)