generate: Set correct working directory for go mod download

generate/generate.go

@@ -8,6 +8,7 @@ import (
 	"io"
 	"io/ioutil"
 	"os/exec"
+	"path/filepath"
 	"sort"
 	"sync"
 
@@ -29,7 +30,8 @@ type goModDownload struct {
 	GoModSum string
 }
 
-func GeneratePkgs(goModPath string, goMod2NixPath string) ([]*schema.Package, error) {
+func GeneratePkgs(directory string, goMod2NixPath string) ([]*schema.Package, error) {
+	goModPath := filepath.Join(directory, "go.mod")
 
 	log.WithFields(log.Fields{
 		"modPath": goModPath,
@@ -57,9 +59,11 @@ func GeneratePkgs(goModPath string, goMod2NixPath string) ([]*schema.Package, er
 	{
 		log.Info("Downloading dependencies")
 
-		stdout, err := exec.Command(
+		cmd := exec.Command(
 			"go", "mod", "download", "--json",
-		).Output()
+		)
+		cmd.Dir = directory
+		stdout, err := cmd.Output()
 		if err != nil {
 			return nil, err
 		}

main.go

@@ -21,11 +21,9 @@ func main() {
 		outDir = *directory
 	}
 
-	goModPath := filepath.Join(*directory, "go.mod")
-
 	goMod2NixPath := filepath.Join(outDir, "gomod2nix.toml")
 	outFile := goMod2NixPath
-	pkgs, err := generate.GeneratePkgs(goModPath, goMod2NixPath)
+	pkgs, err := generate.GeneratePkgs(*directory, goMod2NixPath)
 	if err != nil {
 		panic(err)
 	}