[Feature Request} Improve error messages

[SetTrend]

Description

Currently, Docker engine or Docker daemon error messages are utterly poor and taciturn.

They don't provide any sort of context, stack trace or any other kind of helpful information, assisting in trying to remedy the reported issue.

Please, improve Docker error reporting drastically. It will lower the amount of GitHub and StackOverflow issues and lower your burdon to handle these.

Ref:

• Dockerfile: USER ContainerUser results in "failure in a Windows system call: The user name or password is incorrect. (0x52e)" microsoft/Windows-Containers#490
• Dockerfile COPY instruction doesn't adhere to parser directive "escape" #47776

[thaJeztah]

Thanks for reporting. Yes, these errors on Windows are not (erm) ideal. Unfortunately, I'm not sure how much we can do for these. Looking at the examples from microsoft/Windows-Containers#490 ;

docker: Error response from daemon: container 46a5305c0e305a9b5e7ef5fd746478ea9211b61d136fc7a08b8e4468939514a7 encountered an error during hcs::System::CreateProcess: c:\windows\system32\cmd.exe: failure in a Windows system call: The user name or password is incorrect. (0x52e)
[Event Detail:  Provider: 00000000-0000-0000-0000-000000000000].

And

docker: Error response from daemon: hcs::CreateComputeSystem cf0c577360d731d6e09be5c1eec629751c3891eba85353163c0978cc0c293054: The request is not supported.

Both of these errors originate from the Microsoft hcsshim SDK, and only part of the error comes from the SDK itself; the actual error comes from the Windows kernel (which is proprietary, and effectively a black box).

moby/vendor/github.com/Microsoft/hcsshim/internal/hcs/system.go

Lines 58 to 59 in 9d07820

	func CreateComputeSystem(ctx context.Context, id string, hcsDocumentInterface interface{}) (_ *System, err error) {
	operation := "hcs::CreateComputeSystem"

moby/vendor/github.com/Microsoft/hcsshim/errors.go

Lines 114 to 123 in 9d07820

	if e.Operation != "" {
	s += " encountered an error during " + e.Operation
	}
	switch e.Err.(type) {
	case nil:
	break
	case syscall.Errno:
	s += fmt.Sprintf(": failure in a Windows system call: %s (0x%x)", e.Err, hcserror.Win32FromError(e.Err))
	default:

Unfortunately this often means that docker engine called the Windows kernel API (through their SDK), and "something went wrong"; the underlying error may not (often is not) known to the Docker Engine, so the only thing we can provide in this case is to print all the error information we received.

[SetTrend]

Thanks so much for your very informative reply!

So, from your response I understand that the root of this issue isn't based in this repository but in the microsoft/hcsshim repository? Would they be able to put more "flesh to the bones" and return an error structure providing more details about why the error occured?

I couldn't find the definition of context.Context in that repository. Wouldn't it be beneficial if your repository (i.e., this repository here) would output the contents of the context.Context struct provided to the CreateComputeSystem() call along with the error message in case of an error? (Perhaps only if a "debug" option was provided to docker run.)