Fix datumctl version crashing on unparseable client/server versions

internal/cmd/root.go

@@ -6,6 +6,7 @@ import (
 	"net/http"
 	"os"
 	"path/filepath"
+	"strings"
 	"time"
 
 	"github.com/spf13/cobra"
@@ -64,6 +65,20 @@ func hidePersistentFlags(cmd *cobra.Command, flags ...string) {
 	}
 }
 
+// isVersionSkewParseError reports whether err came from
+// "k8s.io/kubectl/pkg/cmd/version".getVersionSkewWarning failing to parse
+// the client or server GitVersion as semver, rather than from a real
+// connectivity/discovery failure. That check runs after the client/server
+// versions have already been printed, so a malformed version string
+// shouldn't be treated as fatal.
+func isVersionSkewParseError(err error) bool {
+	if err == nil {
+		return false
+	}
+	msg := err.Error()
+	return strings.HasPrefix(msg, "client version error:") || strings.HasPrefix(msg, "server version error:")
+}
+
 func RootCmd() *cobra.Command {
 	// Resolve plugins directory early so ForwardCompletion can use it.
 	// Failures are non-fatal here — if we can't find the dir, completion
@@ -662,6 +677,31 @@ the server.`
 		return nil
 	}
 	versionCmd.GroupID = "other"
+	versionCmd.Run = nil
+	versionCmd.RunE = func(cmd *cobra.Command, args []string) error {
+		o := version.NewOptions(ioStreams)
+		o.ClientOnly, _ = cmd.Flags().GetBool("client")
+		o.Output, _ = cmd.Flags().GetString("output")
+
+		if err := o.Complete(factory, cmd, args); err != nil {
+			return err
+		}
+		if err := o.Validate(); err != nil {
+			return err
+		}
+
+		err := o.Run()
+		if isVersionSkewParseError(err) {
+			// Client/server versions were already printed above; the server
+			// (or, less commonly, the client binary itself) reported a
+			// version string that isn't valid semver, e.g. an unresolved
+			// `git archive` export-subst placeholder like "$Format:%H$".
+			// That shouldn't prevent `datumctl version` from succeeding.
+			fmt.Fprintf(ioStreams.ErrOut, "Warning: could not compare client/server versions: %s\n", err)
+			return nil
+		}
+		return err
+	}
 	rootCmd.AddCommand(versionCmd)
 
 	activityCmd := activity.NewActivityCommand(activity.ActivityCommandOptions{

internal/cmd/version_test.go

@@ -0,0 +1,35 @@
+package cmd
+
+import (
+	"errors"
+	"fmt"
+	"testing"
+)
+
+func TestIsVersionSkewParseError(t *testing.T) {
+	tests := []struct {
+		name string
+		err  error
+		want bool
+	}{
+		{"nil error", nil, false},
+		{
+			"unresolved git archive placeholder in server version",
+			fmt.Errorf("server version error: %w", errors.New(`could not parse pre-release/metadata (-master+$Format:%H$) in version "v0.0.0-master+$Format:%H$"`)),
+			true,
+		},
+		{
+			"unparseable client version",
+			fmt.Errorf("client version error: %w", errors.New(`could not parse "not-a-version" as version`)),
+			true,
+		},
+		{"unrelated error", errors.New("connection refused"), false},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := isVersionSkewParseError(tt.err); got != tt.want {
+				t.Fatalf("isVersionSkewParseError(%v) = %v, want %v", tt.err, got, tt.want)
+			}
+		})
+	}
+}