feat(tls): migrate TLS to the single-kernel library

Consume the single-kernel library's operator-certificate TLS handler
(events.tls.TLS) and TLSManager instead of the charm-side src/relations/tls.py,
stacked on the DPE-10062 Patroni/cluster port (#1788). The TLS events handler
owns the two certificate requirers and is constructor-injected into TLSManager,
whose live-fetch getters read cert/key from them. A charm-side reload bridge
(_reload_tls_after_push) reloads PostgreSQL after the lib handler stores+pushes
certs; it also fires on relation_broken so detaching the TLS operator re-renders
Patroni with TLS disabled.

Removes src/relations/tls.py and push_tls_files_to_workload (now owned by the
lib), routes internal-cert regeneration through _regenerate_internal_cert,
redirects the operator-cert getters to tls_manager, and pins the library to the
TLS stack tip via archive URL (16.3.2 is not yet released).

Signed-off-by: Marcelo Henrique Neppel <marcelo.neppel@canonical.com>

Author: marceloneppel

poetry.lock

@@ -21,7 +21,7 @@ charm-refresh = "^3.1.0.2"
 charmlibs-snap = "^1.0.1"
 charmlibs-systemd = "^1.0.0.post0"
 charmlibs-interfaces-tls-certificates = "^1.8.3"
-postgresql-charms-single-kernel = {extras = ["postgresql", "vm"], version = "16.3.1"}
+postgresql-charms-single-kernel = {url = "https://github.com/canonical/postgresql-single-kernel-library/archive/5aeebec.zip", extras = ["postgresql", "vm"]}
 
 [tool.poetry.group.charm-libs.dependencies]
 # data_platform_libs/v0/data_interfaces.py

pyproject.toml

@@ -109,10 +109,8 @@
     SNAP_USER,
     SPI_MODULE,
     SYSTEM_USERS,
-    TLS_CA_BUNDLE_FILE,
-    TLS_CA_FILE,
-    TLS_CERT_FILE,
-    TLS_KEY_FILE,
+    TLS_CLIENT_RELATION,
+    TLS_PEER_RELATION,
     TRACING_PROTOCOL,
     TRACING_RELATION_NAME,
     UNIT_SCOPE,
@@ -121,12 +119,13 @@
 )
 from single_kernel_postgresql.core.config import CharmConfig
 from single_kernel_postgresql.core.state import CharmState
+from single_kernel_postgresql.events.tls import TLS
 from single_kernel_postgresql.events.tls_transfer import TLSTransfer
 from single_kernel_postgresql.managers.cluster import ClusterManager
 from single_kernel_postgresql.managers.config import ConfigManager
 from single_kernel_postgresql.managers.patroni import PatroniManager
 from single_kernel_postgresql.managers.tls import TLSManager
-from single_kernel_postgresql.utils import label2name, new_password, render_file
+from single_kernel_postgresql.utils import label2name, new_password
 from single_kernel_postgresql.utils.postgresql import (
     ACCESS_GROUP_IDENTITY,
     ACCESS_GROUPS,
@@ -155,7 +154,6 @@
 )
 from constants import (
     MONITORING_SNAP_SERVICE,
-    PATRONI_CONF_PATH,
     PGBACKREST_MONITORING_SNAP_SERVICE,
     POSTGRESQL_DATA_DIR,
     RAFT_PARTNER_PREFIX,
@@ -167,7 +165,6 @@
 from ldap import PostgreSQLLDAP
 from relations.async_replication import PostgreSQLAsyncReplication
 from relations.postgresql_provider import PostgreSQLProvider
-from relations.tls import TLS
 from relations.watcher import PostgreSQLWatcherRelation
 from rotate_logs import RotateLogs
 
@@ -379,11 +376,10 @@ def __init__(self, *args):
 
         # TODO switch to the abstract class base
         # State
-        self.state = CharmState(charm=self, substrate=self.substrate)  # type: ignore
+        self.state = CharmState(charm=self, substrate=self.substrate)
 
         # Managers
         self.patroni_manager = PatroniManager(state=self.state, workload=self.workload)
-        self.tls_manager = TLSManager(state=self.state, workload=self.workload)
         self.cluster_manager = ClusterManager(state=self.state, workload=self.workload)
         self.config_manager = ConfigManager(state=self.state, workload=self.workload)
 
@@ -421,7 +417,31 @@ def __init__(self, *args):
         self.postgresql_client_relation = PostgreSQLProvider(self)
         self.backup = PostgreSQLBackups(self, "s3-parameters")
         self.ldap = PostgreSQLLDAP(self, "ldap")
-        self.tls = TLS(self, PEER_RELATION)
+        # TLS events handler owns the two cert requirers; build it before the TLS
+        # manager so the manager can constructor-inject them for its live-fetch getters.
+        self.tls = TLS(self, self.state, self.workload)
+        self.tls_manager = TLSManager(
+            state=self.state,
+            workload=self.workload,
+            client_certificate=self.tls.client_certificate,
+            peer_certificate=self.tls.peer_certificate,
+        )
+        # Bridge the lib TLS handler's requirer events back into a PostgreSQL reload:
+        # the lib handler stores+pushes certs on certificate_available, then we reload.
+        # Also fires on relation_broken so detaching the TLS operator re-renders Patroni
+        # with TLS disabled.
+        self.framework.observe(
+            self.tls.client_certificate.on.certificate_available, self._reload_tls_after_push
+        )
+        self.framework.observe(
+            self.tls.peer_certificate.on.certificate_available, self._reload_tls_after_push
+        )
+        self.framework.observe(
+            self.on[TLS_CLIENT_RELATION].relation_broken, self._reload_tls_after_push
+        )
+        self.framework.observe(
+            self.on[TLS_PEER_RELATION].relation_broken, self._reload_tls_after_push
+        )
         self.tls_transfer = TLSTransfer(self, PEER_RELATION)
         self.async_replication = PostgreSQLAsyncReplication(self)
         self.watcher_offer = PostgreSQLWatcherRelation(self)
@@ -498,6 +518,49 @@ def substrate(self) -> Substrates:
         """
         return Substrates.VM
 
+    def _reload_tls_after_push(self, event) -> None:
+        """Reload PostgreSQL after the lib TLS handler stores+pushes certs.
+
+        Also fires on the TLS relations' relation_broken so detaching the TLS
+        operator re-renders Patroni with TLS disabled and reloads.
+
+        Mirror the handler's readiness guard: when the internal CA is absent the
+        handler defers its push (no files on disk), so skip the reload to avoid
+        rendering ssl:on against missing TLS files on an already-running unit.
+
+        A transient config-apply failure (Patroni API unreachable, member not
+        started) defers and retries rather than leaving stale TLS state or failing
+        the hook.
+        """
+        if not self.get_secret(APP_SCOPE, "internal-ca"):
+            return
+        # Don't enable TLS in the config until the lib has written the cert files to
+        # disk (its push can defer while this local render would still succeed, which
+        # would start Patroni ssl:on against missing files).
+        if self.is_tls_enabled and not self.tls_manager.client_tls_files_on_disk():
+            event.defer()
+            return
+        try:
+            if not self.update_config():
+                event.defer()
+        except Exception:
+            logger.exception("TLS reload (update_config) failed; deferring")
+            event.defer()
+
+    def _regenerate_internal_cert(self, *, reload: bool = True) -> None:
+        """Generate the internal peer cert, push it to the workload, and (optionally) reload.
+
+        reload=False is used at cluster bootstrap: the leader renders patroni.yml on
+        leader-elected and each replica renders it in _on_peer_relation_changed just
+        before starting Patroni, so a reload here would be redundant. The internal peer
+        cert does not toggle ssl in the config -- only the operator/client cert does, via
+        is_tls_enabled -- so skipping the reload cannot leave a stale ssl setting.
+        """
+        self.tls_manager.generate_internal_peer_cert()
+        self.tls_manager.push_tls_files()
+        if reload:
+            self.update_config()
+
     def _check_and_update_internal_cert(self) -> None:
         """Check if the internal cert CN matches the unit IP and regenerate if needed."""
         try:
@@ -509,7 +572,7 @@ def _check_and_update_internal_cert(self) -> None:
                     != self.state.unit_ip
                 )
             ):
-                self.tls.generate_internal_peer_cert()
+                self._regenerate_internal_cert()
         except Exception:
             logger.exception("Unable to check or update internal cert")
 
@@ -1548,7 +1611,7 @@ def is_standby_cluster(self) -> bool:
     @property
     def is_tls_enabled(self) -> bool:
         """Return whether TLS is enabled."""
-        return all(self.tls.get_client_tls_files())
+        return all(self.tls_manager.get_client_tls_files())
 
     @property
     def _peer_members_ips(self) -> set[str]:
@@ -1759,7 +1822,7 @@ def _on_leader_elected(self, event: LeaderElectedEvent) -> None:  # noqa: C901
             logger.debug("On leader elected failed to reconfigure cluster.")
 
         if not self.get_secret(APP_SCOPE, "internal-ca"):
-            self.tls.generate_internal_peer_ca()
+            self.tls_manager.generate_internal_peer_ca()
         self.update_config()
 
         # Don't update connection endpoints in the first time this event run for
@@ -1946,7 +2009,7 @@ def _on_start(self, event: StartEvent) -> None:
             event.defer()
             return
         if not self.get_secret(UNIT_SCOPE, "internal-cert"):
-            self.tls.generate_internal_peer_cert()
+            self._regenerate_internal_cert(reload=False)
 
         self.unit_peer_data.update({"ip": self.state.unit_ip})
         self._ensure_storage_layout()
@@ -2497,10 +2560,12 @@ def _update_certificate(self) -> None:
         # Request the certificate only if there is already one. If there isn't,
         # the certificate will be generated in the relation joined event when
         # relating to the TLS Certificates Operator.
-        if all(self.tls.get_client_tls_files()) or all(self.tls.get_peer_tls_files()):
+        if all(self.tls_manager.get_client_tls_files()) or all(
+            self.tls_manager.get_peer_tls_files()
+        ):
             self.tls.refresh_tls_certificates_event.emit()
         if self.get_secret(UNIT_SCOPE, "internal-cert"):
-            self.tls.generate_internal_peer_cert()
+            self._regenerate_internal_cert()
 
     @property
     def is_blocked(self) -> bool:
@@ -2582,37 +2647,6 @@ def _peers(self) -> Relation | None:
         """
         return self.model.get_relation(PEER_RELATION)
 
-    def push_tls_files_to_workload(self) -> bool:
-        """Move TLS files to the PostgreSQL storage path and enable TLS."""
-        key, ca, cert = self.tls.get_client_tls_files()
-        if key is not None:
-            render_file(Substrates.VM, f"{PATRONI_CONF_PATH}/{TLS_KEY_FILE}", key, 0o600)
-        if ca is not None:
-            render_file(Substrates.VM, f"{PATRONI_CONF_PATH}/{TLS_CA_FILE}", ca, 0o600)
-        if cert is not None:
-            render_file(Substrates.VM, f"{PATRONI_CONF_PATH}/{TLS_CERT_FILE}", cert, 0o600)
-
-        key, ca, cert = self.tls.get_peer_tls_files()
-        if key is not None:
-            render_file(Substrates.VM, f"{PATRONI_CONF_PATH}/peer_{TLS_KEY_FILE}", key, 0o600)
-        if ca is not None:
-            render_file(Substrates.VM, f"{PATRONI_CONF_PATH}/peer_{TLS_CA_FILE}", ca, 0o600)
-        if cert is not None:
-            render_file(Substrates.VM, f"{PATRONI_CONF_PATH}/peer_{TLS_CERT_FILE}", cert, 0o600)
-
-        render_file(
-            Substrates.VM,
-            f"{PATRONI_CONF_PATH}/{TLS_CA_BUNDLE_FILE}",
-            self.tls.get_peer_ca_bundle(),
-            0o600,
-        )
-
-        try:
-            return self.update_config()
-        except Exception:
-            logger.exception("TLS files failed to push. Error in config update")
-            return False
-
     def push_ca_file_into_workload(self, secret_name: str) -> bool:
         """Move CA certificates file into the PostgreSQL storage path."""
         certs = self.get_secret(UNIT_SCOPE, secret_name)

src/charm.py

@@ -485,7 +485,7 @@ def update_endpoints(self, event: DatabaseRequestedEvent | None = None) -> None:
         tls = "True" if self.charm.is_tls_enabled else "False"
         ca = None
         if tls == "True":
-            _, ca, _ = self.charm.tls.get_client_tls_files()
+            _, ca, _ = self.charm.tls_manager.get_client_tls_files()
         if not ca:
             ca = ""