standard_init_linux.go:190: exec user process caused "no such file or directory" Docker with go basic web app

Question

The very basic web app is created in Go

package main

import(
   "fmt"
   "net/http"
   "os"
)

func hostHandler(w http.ResponseWriter, r *http.Request){
    name, err :=os.Hostname()

    if err != nil {
           panic(err)
        }

        fmt.Fprintf(w, "<h1>HOSTNAME: %s</h1><br>",name)
        fmt.Fprintf(w, "<h1>ENVIRONMENT VARS: </h1><br>")
        fmt.Fprintf(w, "<ul>")

        for _, evar := range os.Environ(){
            fmt.Fprintf(w, "<li>%s</li>",evar)
        }
        fmt.Fprintf(w, "</ul>")

}

func rootHandler(w http.ResponseWriter, r *http.Request){

    fmt.Fprintf(w, "<h1>Awesome site in Go!</h1><br>")
    fmt.Fprintf(w, "<a href='/host/'>Host info</a><br>")

}

func main() {

        http.HandleFunc("/", rootHandler)
        http.HandleFunc("/host/", hostHandler)
        http.ListenAndServe(":8080", nil)


}

Docker File for it

FROM scratch
WORKDIR /home/ubuntu/go
COPY webapp /
EXPOSE 8080
CMD ["/webapp"]

The image is built successfully

ubuntu@ip-172-31-32-125:~/go/src/hello$ docker build -t "webapp" .
Sending build context to Docker daemon  6.152MB
Step 1/5 : FROM scratch
 --->
Step 2/5 : WORKDIR /home/ubuntu/go
 ---> Using cache
 ---> 8810a06c58c7
Step 3/5 : COPY webapp /
 ---> Using cache
 ---> d75222363d3a
Step 4/5 : EXPOSE 8080
 ---> Using cache
 ---> 45de0853de8e
Step 5/5 : CMD ["/webapp"]
 ---> Using cache
 ---> e9f9031f3632
Successfully built e9f9031f3632
Successfully tagged webapp:latest

But when i run the docker its show error.

ubuntu@ip:~/go/src/hello$ docker run webapp
standard_init_linux.go:190: exec user process caused "no such file or directory"

Please guide what is the issue, I am new to docker and go.

Environment-related information

ubuntu@ip:~/go/src/hello$ ls
Dockerfile  webapp
ubuntu@ip:~/go/src/hello$ echo $GOPATH
/home/ubuntu/go

Code was compiled with go build webapp.go command

Answer 1

File not found can mean the file is missing, a script missing the interpreter, or an executable missing a library. In this case, the net import brings in libc by default, as a dynamic linked binary. You should be able to see that with ldd on your binary.

To fix it, you'll need to pass some extra flags:

CGO_ENABLED=0 GOOS=linux GOARCH=amd64 go build -a -tags netgo -ldflags '-w' -o mybin *.go

The above is from: https://medium.com/@diogok/on-golang-static-binaries-cross-compiling-and-plugins-1aed33499671

Answer 2

In my case CGO_ENABLED=0 was the key to fix this problem.

Cgo allows to use inline C code in Go sources, see more: https://golang.org/cmd/cgo/

I reckon by default Cgo links your application dynamically to libc , even if you don't use any inline C.
And libc is missing when you package your application to Docker image FROM scratch

Here is my working Dockerfile :

FROM golang:1.9.2-alpine AS builder
WORKDIR /go/src/app
COPY . .
RUN CGO_ENABLED=0 go install


FROM scratch
WORKDIR /opt
COPY --from=builder /go/bin/app .
ENTRYPOINT ["/opt/app"]

Answer 3

build:

# build
CGO_ENABLED=0 go build -o myapp main.go

dockerfile:

#FROM alpine:3.10
FROM scratch
COPY . /

EXPOSE 8080

CMD ["/myapp", "-c", "app.ini"]

Answer 4

In case you might need CGO_ENABLED because of a dependency like mattn/go-sqlite3 , you can pass static compilation down the chain using this:

RUN go build -ldflags '-extldflags "-static"'

• go build tells go link ( -ldflags )
• to tell the external linker ( -extldflags ) clang or gcc
• to link it's libraries statically, ie not in separate files

Then when the executable is run, it won't try to load an external library like libc.so , or libpthread.so and be unable to find the file "no such file or directory" as soon as it loads.

Before

RUN go build -o myapp

$ ldd myapp
    /lib64/ld-linux-x86-64.so.2 (0x7ff635fb9000)
    libpthread.so.0 => /lib64/ld-linux-x86-64.so.2 (0x7ff635fb9000)
    libdl.so.2 => /lib64/ld-linux-x86-64.so.2 (0x7ff635fb9000)
    libc.so.6 => /lib64/ld-linux-x86-64.so.2 (0x7ff635fb9000)

After

RUN go build -ldflags '-extldflags "-static"' -o myapp

$ ldd myapp
/lib/ld-musl-x86_64.so.1: /usr/bin/walnutcube-api: Not a valid dynamic program

That is good, we don't want it to be a "dynamic program" we want it to be one of the only files on the system in a scratch container.

Answer 5

尝试更改 Dockerfile 中的行

COPY webapp /webapp

Answer 6

我用过这个，它有效

env GOARCH=386 GOOS=linux go build webapp.go

Answer 7

In my case en env was not enough: RUN CGO_ENABLED=0 GOOS=linux GOARCH=amd64

I had to add as well in the build the tags and ldflags: RUN go build -a -tags netgo -ldflags '-w' -o /go/bin/myService *.go