Fall back to local ca.json edit when --ca-url is unset

command/ca/provisioner/provisioner.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"fmt"
 	"net"
+	"os"
 	"time"
 
 	"github.com/pkg/errors"
@@ -105,6 +106,15 @@ type crudClient interface {
 func newCRUDClient(cliCtx *cli.Context, cfgFile string) (crudClient, error) {
 	unauthAdminClient, err := cautils.NewUnauthenticatedAdminClient(cliCtx)
 	if err != nil {
+		// Documented offline workflow: `step ca provisioner add ... --ca-config
+		// ca.json` edits the file locally and must not require --ca-url/--root
+		// when those flags are absent. Fall back only when the config file
+		// exists; otherwise keep the original admin-client error.
+		if cfgFile != "" {
+			if _, statErr := os.Stat(cfgFile); statErr == nil {
+				return newLocalCaConfigClient(cfgFile)
+			}
+		}
 		return nil, fmt.Errorf("error generating admin client: %w", err)
 	}
 
@@ -113,24 +123,28 @@ func newCRUDClient(cliCtx *cli.Context, cfgFile string) (crudClient, error) {
 	err = unauthAdminClient.IsEnabled()
 	switch {
 	case errors.As(err, &netErr) || errors.Is(err, ca.ErrAdminAPINotImplemented):
-		ui.PrintSelected("CA Configuration", cfgFile)
-		cfg, err := config.LoadConfiguration(cfgFile)
-		if err != nil {
-			return nil, fmt.Errorf("error loading configuration: %w", err)
-		}
-		// Assume the ca.json is already valid to avoid enabling all the
-		// features present in step-ca just to modify the provisioners.
-		cfg.SkipValidation = true
-
-		ui.Println()
-		return newCaConfigClient(context.Background(), cfg, cfgFile)
+		return newLocalCaConfigClient(cfgFile)
 	case errors.Is(err, ca.ErrAdminAPINotAuthorized):
 		return cautils.NewAdminClient(cliCtx)
 	default:
 		return nil, err
 	}
 }
 
+func newLocalCaConfigClient(cfgFile string) (crudClient, error) {
+	ui.PrintSelected("CA Configuration", cfgFile)
+	cfg, err := config.LoadConfiguration(cfgFile)
+	if err != nil {
+		return nil, fmt.Errorf("error loading configuration: %w", err)
+	}
+	// Assume the ca.json is already valid to avoid enabling all the
+	// features present in step-ca just to modify the provisioners.
+	cfg.SkipValidation = true
+
+	ui.Println()
+	return newCaConfigClient(context.Background(), cfg, cfgFile)
+}
+
 func parseInstanceAge(ctx *cli.Context) (age string, err error) {
 	if !ctx.IsSet("instance-age") {
 		return

command/ca/provisioner/provisioner_test.go

@@ -3,14 +3,18 @@ package provisioner
 import (
 	"crypto/ed25519"
 	"crypto/rand"
+	"flag"
+	"fmt"
 	"net/netip"
 	"os"
+	"path/filepath"
 	"testing"
 	"time"
 
 	nebula "github.com/slackhq/nebula/cert"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
+	"github.com/urfave/cli"
 )
 
 func TestReadNebulaRoots(t *testing.T) {
@@ -95,3 +99,51 @@ func serializeAndWriteNebulaCert(t *testing.T, tempDir string, cert nebula.Certi
 
 	return file.Name(), data
 }
+
+func TestNewCRUDClient_CaConfigWithoutCaURL(t *testing.T) {
+	t.Parallel()
+
+	dir := t.TempDir()
+	cfgFile := filepath.Join(dir, "ca.json")
+	// Paths need not exist: SkipValidation is set before authority.New.
+	cfg := fmt.Sprintf(`{
+  "root": %q,
+  "crt": %q,
+  "key": %q,
+  "address": ":9000",
+  "dnsNames": ["localhost"],
+  "authority": {
+    "provisioners": []
+  }
+}
+`, filepath.Join(dir, "root.crt"), filepath.Join(dir, "intermediate.crt"), filepath.Join(dir, "intermediate.key"))
+	require.NoError(t, os.WriteFile(cfgFile, []byte(cfg), 0o600))
+
+	app := cli.NewApp()
+	set := flag.NewFlagSet("test", 0)
+	_ = set.String("ca-url", "", "")
+	_ = set.String("root", "", "")
+	_ = set.String("ca-config", cfgFile, "")
+	ctx := cli.NewContext(app, set, nil)
+
+	client, err := newCRUDClient(ctx, cfgFile)
+	require.NoError(t, err)
+	require.NotNil(t, client)
+	_, ok := client.(*caConfigClient)
+	require.True(t, ok, "expected local caConfigClient when --ca-config exists and --ca-url is unset")
+}
+
+func TestNewCRUDClient_MissingCaURLWithoutConfig(t *testing.T) {
+	t.Parallel()
+
+	app := cli.NewApp()
+	set := flag.NewFlagSet("test", 0)
+	_ = set.String("ca-url", "", "")
+	_ = set.String("root", "", "")
+	ctx := cli.NewContext(app, set, nil)
+
+	client, err := newCRUDClient(ctx, "")
+	require.Error(t, err)
+	require.Nil(t, client)
+	require.Contains(t, err.Error(), "ca-url")
+}