go-version: use the version from the go.mod file

Signed-off-by: hectorj2f <[email protected]>

pkg/run/gorun.go

@@ -22,10 +22,9 @@ func GoModTidy(modroot, goVersion string) (string, error) {
 
 		v := versionutil.MustParseGeneric(goVersion)
 		goVersion = fmt.Sprintf("%d.%d", v.Major(), v.Minor())
-
-		log.Printf("Running go mod tidy with go version '%s' ...\n", goVersion)
 	}
 
+	log.Printf("Running go mod tidy with go version '%s' ...\n", goVersion)
 	cmd := exec.Command("go", "mod", "tidy", "-go", goVersion)
 	cmd.Dir = modroot
 	if bytes, err := cmd.CombinedOutput(); err != nil {

pkg/update/update.go

@@ -66,16 +66,26 @@ func checkPackageValues(pkgVersions map[string]*types.Package, modFile *modfile.
 }
 
 func DoUpdate(pkgVersions map[string]*types.Package, cfg *types.Config) (*modfile.File, error) {
+	modpath := path.Join(cfg.Modroot, "go.mod")
+
+	goVersion := cfg.GoVersion
+	if goVersion == "" {
+		// Read the go version from go.mod file and use that one
+		modFile, _, err := ParseGoModfile(modpath)
+		if err != nil {
+			return nil, fmt.Errorf("unable to parse the go mod file with error: %v", err)
+		}
+		goVersion = modFile.Go.Version
+	}
 	// Run go mod tidy before
 	if cfg.Tidy {
-		output, err := run.GoModTidy(cfg.Modroot, cfg.GoVersion)
+		output, err := run.GoModTidy(cfg.Modroot, goVersion)
 		if err != nil {
 			return nil, fmt.Errorf("failed to run 'go mod tidy': %v with output: %v", err, output)
 		}
 	}
 
 	// Read the entire go.mod one more time into memory and check that all the version constraints are met.
-	modpath := path.Join(cfg.Modroot, "go.mod")
 	modFile, content, err := ParseGoModfile(modpath)
 	if err != nil {
 		return nil, fmt.Errorf("unable to parse the go mod file with error: %v", err)
@@ -117,7 +127,7 @@ func DoUpdate(pkgVersions map[string]*types.Package, cfg *types.Config) (*modfil
 
 	// Run go mod tidy
 	if cfg.Tidy {
-		output, err := run.GoModTidy(cfg.Modroot, cfg.GoVersion)
+		output, err := run.GoModTidy(cfg.Modroot, goVersion)
 		if err != nil {
 			return nil, fmt.Errorf("failed to run 'go mod tidy': %v with output: %v", err, output)
 		}