start: insufficient permissions to directories

Fixed a bug where an error did not appear when access rights to the var
directive were insufficient.

Closes #1238

Author: r.inyakin

CHANGELOG.md

@@ -13,6 +13,9 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 
 ### Fixed
 
+- `tt start`: fixed a bug where an error did not appear when access rights
+  to the var directive were insufficient.
+
 ## [2.11.3] - 2026-02-25
 
 The release updates the dependencies and fixes discovering of the available

cli/cmd/start.go

@@ -10,6 +10,7 @@ import (
 	"sync"
 	"syscall"
 
+	"github.com/apex/log"
 	"github.com/spf13/cobra"
 	"github.com/tarantool/tt/cli/cmd/internal"
 	"github.com/tarantool/tt/cli/cmdcontext"
@@ -92,9 +93,12 @@ func startInstancesInteractive(cmdCtx *cmdcontext.CmdCtx, instances []running.In
 		prefix := running.GetAppInstanceName(instCtx) + " "
 		wg.Add(1)
 		go func(inst running.InstanceCtx) {
-			running.RunInstance(ctx, cmdCtx, inst,
+			err := running.RunInstance(ctx, cmdCtx, inst,
 				running.NewColorizedPrefixWriter(os.Stdout, clr, prefix),
 				running.NewColorizedPrefixWriter(os.Stderr, clr, prefix))
+			if err != nil {
+				log.Errorf("failed to run instance %q: %s", prefix, err)
+			}
 			wg.Done()
 		}(instCtx)
 	}

cli/running/running.go

@@ -966,6 +966,16 @@ Cluster config path: %q`, tntVersion.Str, inst.ClusterConfigPath)
 func StartWatchdog(cmdCtx *cmdcontext.CmdCtx, ttExecutable string, instance InstanceCtx,
 	args []string,
 ) error {
+	for _, dataDir := range [...]string{
+		instance.WalDir, instance.VinylDir,
+		instance.MemtxDir, instance.RunDir,
+	} {
+		if err := util.CreateDirectory(dataDir, defaultDirPerms); err != nil {
+			return fmt.Errorf("failed to run instance %q: %s",
+				GetAppInstanceName(instance)+" ", err)
+		}
+	}
+
 	appName := GetAppInstanceName(instance)
 	// If an instance is already running don't try to start it again.
 	// To restart an instance use tt restart command.

test/integration/start/test_start.py

@@ -1,3 +1,5 @@
+import os
+
 import pytest
 import tt_helper
 
@@ -109,3 +111,31 @@ def test_start_multi_inst(tt, tt_app, target):
 )
 def test_start_cluster(tt, tt_app, target):
     check_start(tt, tt_app, target)
+
+
+################################################################
+# Permission denied
+
+
+@pytest.mark.skipif(
+    os.getuid() == 0,
+    reason="Skipping the test, it shouldn't run as root",
+)
+@pytest.mark.tt_app(**tt_multi_inst_app)
+@pytest.mark.parametrize(
+    "tt_running_targets",
+    [
+        pytest.param([], id="running:none"),
+    ],
+)
+def test_start_permission_denied(tt, tt_app):
+    var_dir = tt_app.path("var")
+    os.makedirs(var_dir, exist_ok=True)
+    os.chmod(var_dir, 0o444)
+
+    try:
+        rc, out = tt.exec("start", "app")
+        assert rc != 0
+        assert "permission denied" in out.lower()
+    finally:
+        os.chmod(var_dir, 0o755)