test(e2e): stabilize MariaDB 11 tests and fix restore empty-mode client selection

- add `make clean` and run it before `test-e2e` to avoid stale artifacts
- restore: do not hardcode `mysql` for --empty; use detected mariadb/mysql client
- e2e: improve subprocess error output for easier CI debugging
- e2e: adjust MariaDB readiness checks for socket-only root on MariaDB 11
- e2e: add `wait_for_mariadb_sql` and run SQL readiness checks for dedicated TCP user
- e2e: update MariaDB full/no-copy tests to use dedicated user over TCP and consistent credentials

https://chatgpt.com/share/694ecfb8-f8a8-800f-a1c9-a5f410d4ba02

tests/e2e/helpers.py

@@ -8,14 +8,30 @@ import uuid
 from pathlib import Path
 
 
-def run(cmd: list[str], *, capture: bool = True, check: bool = True, cwd: str | None = None) -> subprocess.CompletedProcess:
-    return subprocess.run(
-        cmd,
-        check=check,
-        cwd=cwd,
-        text=True,
-        capture_output=capture,
-    )
+def run(
+    cmd: list[str],
+    *,
+    capture: bool = True,
+    check: bool = True,
+    cwd: str | None = None,
+) -> subprocess.CompletedProcess:
+    try:
+        return subprocess.run(
+            cmd,
+            check=check,
+            cwd=cwd,
+            text=True,
+            capture_output=capture,
+        )
+    except subprocess.CalledProcessError as e:
+        # Print captured output so failing E2E tests are "live" / debuggable in CI logs
+        print(">>> command failed:", " ".join(cmd))
+        print(">>> exit code:", e.returncode)
+        if e.stdout:
+            print(">>> STDOUT:\n" + e.stdout)
+        if e.stderr:
+            print(">>> STDERR:\n" + e.stderr)
+        raise
 
 
 def sh(cmd: str, *, capture: bool = True, check: bool = True) -> subprocess.CompletedProcess:
@@ -66,13 +82,17 @@ def wait_for_postgres(container: str, *, user: str = "postgres", timeout_s: int
 
 def wait_for_mariadb(container: str, *, root_password: str, timeout_s: int = 90) -> None:
     """
-    Docker-outside-of-Docker friendly readiness: check from inside the DB container.
+    Liveness probe for MariaDB.
+
+    IMPORTANT (MariaDB 11):
+    Root TCP auth is often restricted (unix_socket auth), so a TCP ping like
+    `mariadb-admin -uroot -p... -h localhost ping` can fail even though the server is up.
+    We therefore check readiness via a socket-based query.
     """
     deadline = time.time() + timeout_s
     while time.time() < deadline:
-        # mariadb-admin is present in the official mariadb image
         p = run(
-            ["docker", "exec", container, "sh", "-lc", f"mariadb-admin -uroot -p{root_password} ping -h localhost"],
+            ["docker", "exec", container, "sh", "-lc", "mariadb -uroot --protocol=socket -e \"SELECT 1;\""],
             capture=True,
             check=False,
         )
@@ -82,6 +102,33 @@ def wait_for_mariadb(container: str, *, root_password: str, timeout_s: int = 90)
     raise TimeoutError(f"Timed out waiting for MariaDB readiness in container {container}")
 
 
+def wait_for_mariadb_sql(container: str, *, user: str, password: str, timeout_s: int = 90) -> None:
+    """
+    SQL login readiness for the *dedicated test user* over TCP.
+
+    This is separate from wait_for_mariadb(root) because root may be socket-only,
+    while the tests use a normal user that should work via TCP.
+    """
+    deadline = time.time() + timeout_s
+    while time.time() < deadline:
+        p = run(
+            [
+                "docker",
+                "exec",
+                container,
+                "sh",
+                "-lc",
+                f"mariadb -h 127.0.0.1 -u{user} -p{password} -e \"SELECT 1;\"",
+            ],
+            capture=True,
+            check=False,
+        )
+        if p.returncode == 0:
+            return
+        time.sleep(1)
+    raise TimeoutError(f"Timed out waiting for MariaDB SQL login readiness in container {container}")
+
+
 def backup_run(
     *,
     backups_dir: str,
@@ -111,7 +158,6 @@ def backup_run(
     try:
         run(cmd, capture=True, check=True)
     except subprocess.CalledProcessError as e:
-        # Print captured output so failing E2E tests are "live" / debuggable in CI logs
         print(">>> baudolo failed (exit code:", e.returncode, ")")
         if e.stdout:
             print(">>> baudolo STDOUT:\n" + e.stdout)