On Mon, Oct 25, 2021 at 4:45 PM Nir Soffer <nsoffer@redhat.com> wrote:
I'm playing with libnbd go module, planning to use it in a new command[1]
The biggest obstacle for me is that the module is not published in a way that Go developers expect.
The module is listed in: https://pkg.go.dev/github.com/libguestfs/libnbd/golang
But the module actually lives in: https://github.com/libguestfs/libnbd/tree/master/golang/src/libguestfs.org/l...
So the pkg.go.dev page is broken, .e.g no there is no documation or license, and the suggested import is wrong.
The module name is "libguestfs.org/libnbd". But if you try to use it, for example in the (improved) example from libnbd-golang.pod:
$ cat test.go package main
import "fmt" import "libguestfs.org/libnbd"
func main() { h, err := libnbd.Create() if err != nil { panic(err) } defer h.Close() uri := "nbd://localhost" err = h.ConnectUri(uri) if err != nil { panic(err) } size, err := h.GetSize() if err != nil { panic(err) } fmt.Printf("size of %s = %d\n", uri, size) }
$ go mod init example/test go: creating new go.mod: module example/test go: to add module requirements and sums: go mod tidy
$ go mod tidy go: finding module for package libguestfs.org/libnbd example/test imports libguestfs.org/libnbd: cannot find module providing package libguestfs.org/libnbd: unrecognized import path "libguestfs.org/libnbd": reading https://libguestfs.org/libnbd?go-get=1: 404 Not Found
If we use libguestfs.org, https://libguestfs.org/libnbd?go-get=1 should return the expected metadata instead of 404.
But even if "libguestfs.org/libnbd" would work, we cannot use the module from the source since the source is missing the generated files (wrappers.go, binding.go, ...).
It looks like the only ways to use the module are:
- Vendor the go code from the tarball.
I did not try this since I don't want to copy libnbd into source into my project.
- Clone and build libnbd locally, and replace libguestfs.org with the path to your local source
$ go mod edit -replace libguestfs.org/libnbd=../../src/libnbd/golang/src/libguestfs.org/libnbd $ go mod tidy go: found libguestfs.org/libnbd in libguestfs.org/libnbd v0.0.0-00010101000000-000000000000
$ cat go.mod module example/test
go 1.16
replace libguestfs.org/libnbd => ../../src/libnbd/golang/src/libguestfs.org/libnbd
require libguestfs.org/libnbd v0.0.0-00010101000000-000000000000
But the version is wrong - it should be v1.10.0. I think the issue is missing tag: https://golang.org/ref/mod#vcs-version
If a module is defined in a subdirectory within the repository, that is, the module subdirectory portion of the module path is not empty, then each tag name must be prefixed with the module subdirectory, followed by a slash. For example, the module golang.org/x/tools/gopls is defined in the gopls subdirectory of the repository with root path golang.org/x/tools. The version v0.4.0 of that module must have the tag named gopls/v0.4.0 in that repository.
So the linbd project needs a tag like: golang/src/libguestfs.org/libnbd/v1.10.0
Removing the "src/libguestfs.org" directories will clean things up: golang/libnbd/v1.10.0
I hope we can solve this issue. Making the go binding easy to use for developers is important for making libnbd more popular in the Go community.
Another issue, what is the license of the libnbd Go module? The project license is LGPL 2.1, but how can tools find the license when we point them to a subdirectory?, and the license is not using a standard file name? Some modules have a GPL header, and some LGPL: $ git grep -n 'GNU General Public' golang | wc -l 66 $ git grep -n 'GNU Lesser General Public' golang | wc -l 6 I guess using LGPL is the right license? I think the directory with the module should have a LICENSE file to make this clear, and libnbd-golang.pod should have a LICENSE section. Nir