gomod2nix generate results in error path is not valid

[storvik]

Trying to use this to build a go package using some private modules. Looks like I should be able to do that using generate and import, but getting error path is not valid. Tried without private modules and the problem persists.

Describe the bug
nix-instantiate returns error: path /nix/store/*hash*-*package* is not valid. when running gomod2nix import.

To Reproduce

1. go mod init
2. create main.go file with content:

package main

import (
	"log"

	"github.com/rs/zerolog"
	"github.com/rs/zerolog/log"
)

func main() {
	zerolog.SetGlobalLevel(zerolog.InfoLevel)

	log.Error().Msg("Error message")
	log.Warn().Msg("Warning message")

}

3. go mod tidy
4. gomod2nix generate (succeeds)
5. gomod2nix import (fails)

Expected behavior
Expected go dependencies to be imported into the nix store.

Environment

• Ubuntu running under WSL
• NixOS from recent nixos/unstable

Tested both OS but the same thing happened.

Additional context
The complete log is here

storvik@computer:~/developer/golang/gonixtest$ gomod2nix generate
INFO[0000] Parsing go.mod                                modPath=go.mod
INFO[0000] Downloading dependencies
INFO[0000] Done downloading dependencies
INFO[0000] Wrote: gomod2nix.toml
storvik@computer:~/developer/golang/gonixtest$ gomod2nix import
INFO[0000] Parsing go.mod                                modPath=go.mod
INFO[0000] Downloading dependencies
INFO[0000] Done downloading dependencies
INFO[0000] Importing sources                             goPackagePath=github.com/rs/zerolog
INFO[0000] Importing sources                             goPackagePath=github.com/mattn/go-isatty
INFO[0000] Importing sources                             goPackagePath=golang.org/x/sys
INFO[0000] Importing sources                             goPackagePath=github.com/mattn/go-colorable
error: path '/nix/store/83frfpjglh25xz7s32w28fw1p54k9170-go-isatty_v0.0.14' is not valid
(use '--show-trace' to show detailed location information)
error: path '/nix/store/gfqmz2qc8qsl29xan4kd3bdy7qjdnmdj-zerolog_v1.27.0' is not valid
(use '--show-trace' to show detailed location information)
/home/storvik/.nix-profile/bin/nix-instantiate --eval --expr
builtins.filterSource (name: type: baseNameOf name != ".DS_Store") (
  builtins.path {
    path = "/home/storvik/developer/gopath/pkg/mod/github.com/mattn/[email protected]";
    name = "go-isatty_v0.0.14";
  }
)

error: path '/nix/store/drh29dg8s120a21f1yicfrxsr4ykcwf0-go-colorable_v0.1.12' is not valid
(use '--show-trace' to show detailed location information)
/home/storvik/.nix-profile/bin/nix-instantiate --eval --expr
builtins.filterSource (name: type: baseNameOf name != ".DS_Store") (
  builtins.path {
    path = "/home/storvik/developer/gopath/pkg/mod/github.com/rs/[email protected]";
    name = "zerolog_v1.27.0";
  }
)

/home/storvik/.nix-profile/bin/nix-instantiate --eval --expr
builtins.filterSource (name: type: baseNameOf name != ".DS_Store") (
  builtins.path {
    path = "/home/storvik/developer/gopath/pkg/mod/github.com/mattn/[email protected]";
    name = "go-colorable_v0.1.12";
  }
)

panic: exit status 1

goroutine 1 [running]:
github.com/tweag/gomod2nix/internal/cmd.glob..func1(0xb16ee0?, {0x822d54?, 0x0?, 0x0?})
        /build/source/internal/cmd/root.go:109 +0x48
github.com/spf13/cobra.(*Command).execute(0xb16ee0, {0xb4d048, 0x0, 0x0})
        /build/source/vendor/github.com/spf13/cobra/command.go:860 +0x663
github.com/spf13/cobra.(*Command).ExecuteC(0xb169e0)
        /build/source/vendor/github.com/spf13/cobra/command.go:974 +0x3b4
github.com/spf13/cobra.(*Command).Execute(...)
        /build/source/vendor/github.com/spf13/cobra/command.go:902
github.com/tweag/gomod2nix/internal/cmd.Execute()
        /build/source/internal/cmd/root.go:124 +0x25
main.main()
        /build/source/main.go:6 +0x17
error: path '/nix/store/0076f6qx7f05ivh6hi71ddx0rnmplnhw-sys_v0.0.0-20210927094055-39ccf1dd6fa6' is not valid
(use '--show-trace' to show detailed location information)

I've tried to run the nix-instantiate command manually too, but same error.

A working solution to use private repos would be great, this is a promising start. Thanks for your contributions to the community.

[jgresty]

Oddly the expression evaluates perfectly fine in a nix repl, I wish nix-instantiate would give useful errors...

[jjthiessen]

I'm having the same issues. It seems to affect not only all private repos, but also public ones where the module ref doesn't correspond to a released version (updating to a given commit or branch — e.g., go get example.net/fake/mod@branch).

For example, I'm getting this (upon gomod2nix import) in one of my projects:

INFO[0000] Importing sources                             goPackagePath=golang.org/x/oauth2
error: path '/nix/store/m5x1qfq4yqdn8zyx4gm4z12m112mmj9b-oauth2_v0.0.0-20220411215720-9780585627b5' is not valid
(use '--show-trace' to show detailed location information)
/run/current-system/sw/bin/nix-instantiate --eval --expr 
builtins.filterSource (name: type: baseNameOf name != ".DS_Store") (
  builtins.path {
    path = "/home/jt/go/pkg/mod/golang.org/x/[email protected]";
    name = "oauth2_v0.0.0-20220411215720-9780585627b5";
  }
)

Like @jgresty said, running it in nix repl works (and, moreover, resolves the issue for future invocations).
Another way around it is to run nix-instantiate without --eval first, like so (original+show-trace, no eval+show-trace, original+show-trace):

$ /run/current-system/sw/bin/nix-instantiate --eval --expr 'builtins.filterSource (name: type: baseNameOf name != ".DS_Store") (
  builtins.path {
    path = "/home/jt/go/pkg/mod/golang.org/x/[email protected]";
    name = "oauth2_v0.0.0-20220411215720-9780585627b5";
  }
)' --show-trace
error: path '/nix/store/m5x1qfq4yqdn8zyx4gm4z12m112mmj9b-oauth2_v0.0.0-20220411215720-9780585627b5' is not valid

       … while adding path '/nix/store/m5x1qfq4yqdn8zyx4gm4z12m112mmj9b-oauth2_v0.0.0-20220411215720-9780585627b5'

       at «string»:1:1:

            1| builtins.filterSource (name: type: baseNameOf name != ".DS_Store") (
             | ^
            2|   builtins.path {

$ /run/current-system/sw/bin/nix-instantiate --expr 'builtins.filterSource (name: type: baseNameOf name != ".DS_Store") (
  builtins.path {
    path = "/home/jt/go/pkg/mod/golang.org/x/[email protected]";
    name = "oauth2_v0.0.0-20220411215720-9780585627b5";
  }
)' --show-trace
error: expression does not evaluate to a derivation (or a set or list of those)

$ /run/current-system/sw/bin/nix-instantiate --eval --expr 'builtins.filterSource (name: type: baseNameOf name != ".DS_Store") (
  builtins.path {
    path = "/home/jt/go/pkg/mod/golang.org/x/[email protected]";
    name = "oauth2_v0.0.0-20220411215720-9780585627b5";
  }
)' --show-trace
"/nix/store/c7z9bm9qzashlcqiv5v2jwcch6gq2hwv-m5x1qfq4yqdn8zyx4gm4z12m112mmj9b-oauth2_v0.0.0-20220411215720-9780585627b5"

I haven't looked at the gomod2nix import code, but I imagine it wouldn't be too difficult to update it to make it work (I'm not sure whether it can be done in a single invocation of nix-instantiate, or not, or even whether it's better to run something else here).

🤷

[jjthiessen]

I just noticed that I'm also getting

error: path '/nix/store/mqn6p2m3qvzqwan59c3xlyvjxgjjhyhy-sys_v0.1.0' is not valid
(use '--show-trace' to show detailed location information)
/run/current-system/sw/bin/nix-instantiate --eval --expr 
builtins.filterSource (name: type: baseNameOf name != ".DS_Store") (
  builtins.path {
    path = "/home/jt/go/pkg/mod/golang.org/x/[email protected]";
    name = "sys_v0.1.0";
  }
)

so I'm guessing that it's actually more general/not specific to the handling of private or untagged module versions.

[jjthiessen]

It looks like nix eval --impure --expr ... would be a suitable replacement (but would require a semi-recent nix version — OTOH, it would work).

[jjthiessen]

@storvik, I should probably have reread your original issue description before trying to add my own notes/comments. I just reread now and saw where you said (only three sentences in, even) that it wasn't specific to private (or untagged) repos (and refs), but I already came here having discovered the same issue from working with private modules, and just latched on to that instead.

Still, either using nix eval --impure --expr ... or nix-instantiate --expr ...; nix-instantiate --eval --expr ... should work.