Fiber: 🐛 docker app with prefork fails

[palevoo]

Fiber version
v2.2.0
Issue description
When run dockerized app with prefork enabled it fails with an error straight after starting

 ┌───────────────────────────────────────────────────┐  ┌───────────────────────────────────────────────────┐
 │                    Fiber v2.2.0                   │  │ Child PIDs ... 12, 13, 14, 17, 25, 42             │
 │                http://127.0.0.1:80                │  └───────────────────────────────────────────────────┘
 │                                                   │ 
 │ Handlers ............. 0  Threads ............. 6 │ 
 │ Prefork ........ Enabled  PID ................. 1 │ 
 └───────────────────────────────────────────────────┘ 

2020/11/26 14:06:04 exit status 1

No problem with building the container
Also works with prefork disabled
Code snippet
App with prefork

package main

import (
    "log"
    "github.com/gofiber/fiber/v2"
)

func main()  {
     app := fiber.New(fiber.Config{
       Prefork: true,
     })

    log.Fatal(app.Listen(":80"))
}

FROM golang:alpine

RUN apk update \
        && apk upgrade \
         && apk --update add --no-cache ca-certificates openssl git tzdata

ENV INSTALL_PATH=/go/src/test/

ENV RUN_PATH=/go/src/test/test

RUN mkdir -p $INSTALL_PATH

WORKDIR $INSTALL_PATH

ADD . $INSTALL_PATH

RUN go get

RUN go build

CMD ["/bin/sh", "-c", "$RUN_PATH"]

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[alfuhigi]

Try to use other machine version something that come with full version like golang:1.15.3 or something else without alpine tags

app.go

package main

import (
    "log"

    "github.com/gofiber/fiber/v2"
)

func main() {
    app := fiber.New(fiber.Config{
        Prefork: true,
    })

    log.Fatal(app.Listen(":80"))
}

Dockerfile

FROM golang:1.15.3

ENV INSTALL_PATH=/app

ENV RUN_PATH=./app

RUN mkdir -p $INSTALL_PATH

WORKDIR $INSTALL_PATH

ADD ./app $INSTALL_PATH

RUN go get

RUN go build -ldflags="-s -w" -o app .

CMD ./app

app structure

.
├── Dockerfile
├── app
   ├── app.go
   ├── go.mod
   └── go.sum

[kunagpal]

@alfuhigi Thanks for sharing the workaround!
I'm facing the same issue, is there no way to use Prefork on Alpine Linux? 🤔

[amaury-tobias]

in https://github.com/gofiber/fiber/blob/master/prefork.go 133 Use PID to exit

// if it is equal to 1 (init process ID),
// it indicates that the master process has exited
for range time.NewTicker(time.Millisecond * 500).C {
    if os.Getppid() == 1 {
        os.Exit(1)
    }
}

on Docker the process start on PID 1

 ┌───────────────────────────────────────────────────┐  ┌───────────────────────────────────────────────────┐
 │                    Fiber v2.2.0                   │  │ Child PIDs ... 12, 13, 14, 17, 25, 42             │
 │                http://127.0.0.1:80                │  └───────────────────────────────────────────────────┘
 │                                                   │ 
 │ Handlers ............. 0  Threads ............. 6 │ 
 │ Prefork ........ Enabled  PID ................. 1 │ 
 └───────────────────────────────────────────────────┘ 

So I run the image with docker run -it --pid=host fiber-test and works perfect
reference

➜  fiber docker run -it --pid=host fiber-test

 ┌───────────────────────────────────────────────────┐  ┌───────────────────────────────────────────────────┐
 │                    Fiber v2.2.3                   │  │ Child PIDs ... 3565, 3566                         │
 │                http://127.0.0.1:80                │  └───────────────────────────────────────────────────┘
 │                                                   │
 │ Handlers ............. 0  Processes ........... 2 │
 │ Prefork ........ Enabled  PID .............. 3529 │
 └───────────────────────────────────────────────────┘