[DPE-7584] Update single kernel library to fix tmpfs ownership and permission after reboot

pyproject.toml

@@ -19,7 +19,7 @@ pysyncobj = "^0.3.14"
 psutil = "^7.1.0"
 charm-refresh = "^3.1.0.2"
 httpx = "^0.28.1"
-postgresql-charms-single-kernel = "^0.0.1"
+postgresql-charms-single-kernel = "16.0.2"
 
 [tool.poetry.group.charm-libs.dependencies]
 # data_platform_libs/v0/data_interfaces.py

src/cluster.py

@@ -31,6 +31,7 @@
 from requests.auth import HTTPBasicAuth
 from single_kernel_postgresql.config.literals import (
     PEER,
+    POSTGRESQL_STORAGE_PERMISSIONS,
     REWIND_USER,
     USER,
 )
@@ -229,7 +230,7 @@ def configure_patroni_on_unit(self):
 
         # Expected permission
         # Replicas refuse to start with the default permissions
-        os.chmod(POSTGRESQL_DATA_PATH, 0o750)  # noqa: S103
+        os.chmod(POSTGRESQL_DATA_PATH, POSTGRESQL_STORAGE_PERMISSIONS)
 
     def _change_owner(self, path: str) -> None:
         """Change the ownership of a file or a directory to the postgres user.

tests/integration/test_tmpfs_restart.py

@@ -0,0 +1,100 @@
+#!/usr/bin/env python3
+# Copyright 2025 Canonical Ltd.
+# See LICENSE file for licensing details.
+
+import logging
+import subprocess
+
+import jubilant
+import psycopg2
+import pytest
+
+from .helpers import DATABASE_APP_NAME
+from .jubilant_helpers import get_credentials
+
+logger = logging.getLogger(__name__)
+
+TIMEOUT = 20 * 60
+RELATION_ENDPOINT = "postgresql"
+DATA_INTEGRATOR_APP_NAME = "data-integrator"
+
+
+@pytest.mark.abort_on_fail
+def test_deploy_with_tmpfs_storage(juju: jubilant.Juju, charm) -> None:
+    """Deploy PostgreSQL with tmpfs temp storage and data-integrator."""
+    # Deploy database app with tmpfs for temporary storage.
+    if DATABASE_APP_NAME not in juju.status().apps:
+        logger.info("Deploying PostgreSQL with tmpfs temporary storage")
+        juju.deploy(
+            charm,
+            app=DATABASE_APP_NAME,
+            num_units=1,
+            config={"profile": "testing"},
+            storage={"temp": "5G,tmpfs"},
+        )
+
+    # Deploy data-integrator to get credentials.
+    if DATA_INTEGRATOR_APP_NAME not in juju.status().apps:
+        logger.info("Deploying data-integrator")
+        juju.deploy(DATA_INTEGRATOR_APP_NAME, config={"database-name": "test"})
+
+    # Relate if not already related
+    status = juju.status()
+    if not status.apps[DATABASE_APP_NAME].relations.get(RELATION_ENDPOINT):
+        juju.integrate(DATA_INTEGRATOR_APP_NAME, DATABASE_APP_NAME)
+
+    logger.info("Waiting for both applications to become active")
+    juju.wait(
+        lambda s: jubilant.all_active(s, DATABASE_APP_NAME, DATA_INTEGRATOR_APP_NAME),
+        timeout=TIMEOUT,
+    )
+
+
+def test_restart_and_temp_table(juju: jubilant.Juju) -> None:
+    """Restart the LXD machine and verify TEMP TABLE creation works afterwards."""
+    unit_name = f"{DATABASE_APP_NAME}/0"
+
+    # Find machine name and restart
+    status = juju.status()
+    unit_info = status.get_units(unit_name.split("/")[0]).get(unit_name)
+    machine_name = None
+    if unit_info:
+        machine_id = getattr(unit_info, "machine", None)
+        if machine_id:
+            # Look up the machine object in status and try common attributes that hold the LXD name
+            machine_obj = (
+                getattr(status, "machines", {}).get(machine_id)
+                if hasattr(status, "machines")
+                else None
+            )
+            if machine_obj:
+                machine_name = getattr(machine_obj, "instance_id", None)
+
+    if machine_name is None:
+        raise RuntimeError("Unable to determine LXD machine/container name for unit " + unit_name)
+
+    logger.info(f"Restarting LXD machine {machine_name}")
+    subprocess.check_call(["lxc", "restart", machine_name])
+
+    # Wait for unit to go active/idle again
+    logger.info("Waiting for PostgreSQL unit to become active after restart")
+    juju.wait(
+        lambda s: jubilant.all_active(s, DATABASE_APP_NAME, DATA_INTEGRATOR_APP_NAME),
+        delay=30,
+        timeout=TIMEOUT,
+    )
+
+    # Obtain credentials via data-integrator action
+    creds = get_credentials(juju, f"{DATA_INTEGRATOR_APP_NAME}/0")
+    uri = creds[RELATION_ENDPOINT]["uris"]
+
+    # Connect and create a TEMPORARY TABLE
+    connection = None
+    try:
+        connection = psycopg2.connect(uri)
+        connection.autocommit = True
+        with connection.cursor() as cur:
+            cur.execute("CREATE TEMPORARY TABLE test (lines TEXT);")
+    finally:
+        if connection is not None:
+            connection.close()

tests/spread/test_tmpfs_restart.py/task.yaml

@@ -0,0 +1,7 @@
+summary: test_tmpfs_restart.py
+environment:
+  TEST_MODULE: test_tmpfs_restart.py
+execute: |
+  tox run -e integration -- "tests/integration/$TEST_MODULE" --model testing --alluredir="$SPREAD_TASK/allure-results"
+artifacts:
+  - allure-results

tests/unit/test_cluster.py

@@ -503,7 +503,7 @@ def test_configure_patroni_on_unit(peers_ips, patroni):
 
         _open.assert_called_once_with(CREATE_CLUSTER_CONF_PATH, "a")
         _chmod.assert_called_once_with(
-            "/var/snap/charmed-postgresql/common/var/lib/postgresql", 488
+            "/var/snap/charmed-postgresql/common/var/lib/postgresql", 448
         )