fix: gomod.env not being used (#3434)

Fixes  #3426

Signed-off-by: Carlos A Becker <caarlos0@users.noreply.github.com>

internal/pipe/gomod/gomod.go

@@ -33,7 +33,9 @@ func (Pipe) Run(ctx *context.Context) error {
 	if ctx.Config.GoMod.Mod != "" {
 		flags = append(flags, "-mod="+ctx.Config.GoMod.Mod)
 	}
-	out, err := exec.CommandContext(ctx, ctx.Config.GoMod.GoBinary, flags...).CombinedOutput()
+	cmd := exec.CommandContext(ctx, ctx.Config.GoMod.GoBinary, flags...)
+	cmd.Env = append(ctx.Env.Strings(), ctx.Config.GoMod.Env...)
+	out, err := cmd.CombinedOutput()
 	result := strings.TrimSpace(string(out))
 	if result == go115NotAGoModuleError || result == go116NotAGoModuleError {
 		return pipe.Skip("not a go module")

internal/pipe/gomod/gomod_test.go

@@ -29,6 +29,19 @@ func TestRunCustomMod(t *testing.T) {
 	require.Equal(t, "github.com/goreleaser/goreleaser", ctx.ModulePath)
 }
 
+func TestCustomEnv(t *testing.T) {
+	bin := filepath.Join(t.TempDir(), "go.bin")
+	require.NoError(t, os.WriteFile(bin, []byte("#!/bin/sh\nenv | grep -qw FOO=bar"), 0o755))
+	ctx := context.New(config.Project{
+		GoMod: config.GoMod{
+			GoBinary: bin,
+			Env:      []string{"FOO=bar"},
+		},
+	})
+	require.NoError(t, Pipe{}.Default(ctx))
+	require.NoError(t, Pipe{}.Run(ctx))
+}
+
 func TestRunOutsideGoModule(t *testing.T) {
 	dir := testlib.Mktmp(t)
 	require.NoError(t, os.WriteFile(filepath.Join(dir, "main.go"), []byte("package main\nfunc main() {println(0)}"), 0o666))

www/docs/customization/build.md

@@ -60,7 +60,8 @@ builds:
       - feature
 
     # Custom environment variables to be set during the builds.
-    # Default is empty.
+    #
+    # Default: `os.Environ()` merged with what you set the root `env` section.
     env:
       - CGO_ENABLED=0
 

www/docs/customization/verifiable_builds.md

@@ -18,12 +18,13 @@ gomod:
   # this setting.
   # Notice: for this to work your `build.main` must be a package, not a `.go` file.
   #
-  # Default is false.
+  # Default: false.
   proxy: true
 
   # If proxy is true, use these environment variables when running `go mod`
   # commands (namely, `go mod tidy`).
-  # Defaults to `os.Environ()`.
+  #
+  # Default: `os.Environ()` merged with what you set the root `env` section.
   env:
     - GOPROXY=https://proxy.golang.org,direct
     - GOSUMDB=sum.golang.org
@@ -36,7 +37,8 @@ gomod:
   mod: mod
 
   # Which Go binary to use.
-  # Defaults to `go`.
+  #
+  # Default: `go`.
   gobinary: go1.17
 ```