Merge pull request #88 from canonical/update-tls-lib

fix issues with tls on immediate relation

Author: MiaAltieri

lib/charms/mongodb/v1/mongodb_tls.py

@@ -8,10 +8,11 @@
 external relation.
 """
 import base64
+import json
 import logging
 import re
 import socket
-from typing import List, Optional, Tuple
+from typing import Optional, Tuple
 
 from charms.tls_certificates_interface.v3.tls_certificates import (
     CertificateAvailableEvent,
@@ -20,6 +21,8 @@
     generate_csr,
     generate_private_key,
 )
+from cryptography import x509
+from cryptography.hazmat.backends import default_backend
 from ops.charm import ActionEvent, RelationBrokenEvent, RelationJoinedEvent
 from ops.framework import Object
 from ops.model import ActiveStatus, MaintenanceStatus, WaitingStatus
@@ -28,7 +31,8 @@
 
 UNIT_SCOPE = Config.Relations.UNIT_SCOPE
 Scopes = Config.Relations.Scopes
-
+SANS_DNS_KEY = "sans_dns"
+SANS_IPS_KEY = "sans_ips"
 
 # The unique Charmhub library identifier, never change it
 LIBID = "e02a50f0795e4dd292f58e93b4f493dd"
@@ -38,7 +42,9 @@
 
 # Increment this PATCH version before using `charmcraft publish-lib` or reset
 # to 0 if you are raising the major API version
-LIBPATCH = 2
+LIBPATCH = 5
+
+WAIT_CERT_UPDATE = "wait-cert-updated"
 
 logger = logging.getLogger(__name__)
 
@@ -104,12 +110,13 @@ def request_certificate(
         else:
             key = self._parse_tls_file(param)
 
+        sans = self.get_new_sans()
         csr = generate_csr(
             private_key=key,
             subject=self._get_subject_name(),
             organization=self._get_subject_name(),
-            sans=self._get_sans(),
-            sans_ip=[str(self.charm.model.get_binding(self.peer_relation).network.bind_address)],
+            sans=sans[SANS_DNS_KEY],
+            sans_ip=sans[SANS_IPS_KEY],
         )
         self.set_tls_secret(internal, Config.TLS.SECRET_KEY_LABEL, key.decode("utf-8"))
         self.set_tls_secret(internal, Config.TLS.SECRET_CSR_LABEL, csr.decode("utf-8"))
@@ -118,9 +125,8 @@ def request_certificate(
         label = "int" if internal else "ext"
         self.charm.unit_peer_data[f"{label}_certs_subject"] = self._get_subject_name()
         self.charm.unit_peer_data[f"{label}_certs_subject"] = self._get_subject_name()
-
-        if self.charm.model.get_relation(Config.TLS.TLS_PEER_RELATION):
-            self.certs.request_certificate_creation(certificate_signing_request=csr)
+        self.certs.request_certificate_creation(certificate_signing_request=csr)
+        self.set_waiting_for_cert_to_update(internal=internal, waiting=True)
 
     @staticmethod
     def _parse_tls_file(raw_content: str) -> bytes:
@@ -158,12 +164,18 @@ def _on_tls_relation_joined(self, event: RelationJoinedEvent) -> None:
 
     def _on_tls_relation_broken(self, event: RelationBrokenEvent) -> None:
         """Disable TLS when TLS relation broken."""
-        logger.debug("Disabling external and internal TLS for unit: %s", self.charm.unit.name)
+        if not self.charm.db_initialised:
+            logger.info("Deferring %s. db is not initialised.", str(type(event)))
+            event.defer()
+            return
+
         if self.charm.upgrade_in_progress:
             logger.warning(
                 "Disabling TLS is not supported during an upgrade. The charm may be in a broken, unrecoverable state."
             )
 
+        logger.debug("Disabling external and internal TLS for unit: %s", self.charm.unit.name)
+
         for internal in [True, False]:
             self.set_tls_secret(internal, Config.TLS.SECRET_CA_LABEL, None)
             self.set_tls_secret(internal, Config.TLS.SECRET_CERT_LABEL, None)
@@ -188,6 +200,11 @@ def _on_certificate_available(self, event: CertificateAvailableEvent) -> None:
             event.defer()
             return
 
+        if not self.charm.db_initialised:
+            logger.info("Deferring %s. db is not initialised.", str(type(event)))
+            event.defer()
+            return
+
         int_csr = self.get_tls_secret(internal=True, label_name=Config.TLS.SECRET_CSR_LABEL)
         ext_csr = self.get_tls_secret(internal=False, label_name=Config.TLS.SECRET_CSR_LABEL)
 
@@ -208,12 +225,13 @@ def _on_certificate_available(self, event: CertificateAvailableEvent) -> None:
         )
         self.set_tls_secret(internal, Config.TLS.SECRET_CERT_LABEL, event.certificate)
         self.set_tls_secret(internal, Config.TLS.SECRET_CA_LABEL, event.ca)
+        self.set_waiting_for_cert_to_update(internal=internal, waiting=False)
 
         if self.charm.is_role(Config.Role.CONFIG_SERVER) and internal:
             self.charm.cluster.update_ca_secret(new_ca=event.ca)
             self.charm.config_server.update_ca_secret(new_ca=event.ca)
 
-        if self.waiting_for_certs():
+        if self.is_waiting_for_both_certs():
             logger.debug(
                 "Defer till both internal and external TLS certificates available to avoid second restart."
             )
@@ -235,7 +253,7 @@ def _on_certificate_available(self, event: CertificateAvailableEvent) -> None:
             # clear waiting status if db service is ready
             self.charm.status.set_and_share_status(ActiveStatus())
 
-    def waiting_for_certs(self):
+    def is_waiting_for_both_certs(self) -> bool:
         """Returns a boolean indicating whether additional certs are needed."""
         if not self.get_tls_secret(internal=True, label_name=Config.TLS.SECRET_CERT_LABEL):
             logger.debug("Waiting for internal certificate.")
@@ -268,21 +286,25 @@ def _on_certificate_expiring(self, event: CertificateExpiringEvent) -> None:
             == self.get_tls_secret(internal=True, label_name=Config.TLS.SECRET_CERT_LABEL).rstrip()
         ):
             logger.debug("The internal TLS certificate expiring.")
-
             internal = True
         else:
             logger.error("An unknown certificate expiring.")
             return
 
         logger.debug("Generating a new Certificate Signing Request.")
+        self.request_new_certificates(internal)
+
+    def request_new_certificates(self, internal: bool) -> None:
+        """Requests the renewel of a new certificate."""
         key = self.get_tls_secret(internal, Config.TLS.SECRET_KEY_LABEL).encode("utf-8")
         old_csr = self.get_tls_secret(internal, Config.TLS.SECRET_CSR_LABEL).encode("utf-8")
+        sans = self.get_new_sans()
         new_csr = generate_csr(
             private_key=key,
             subject=self._get_subject_name(),
             organization=self._get_subject_name(),
-            sans=self._get_sans(),
-            sans_ip=[str(self.charm.model.get_binding(self.peer_relation).network.bind_address)],
+            sans=sans[SANS_DNS_KEY],
+            sans_ip=sans[SANS_IPS_KEY],
         )
         logger.debug("Requesting a certificate renewal.")
 
@@ -292,21 +314,53 @@ def _on_certificate_expiring(self, event: CertificateExpiringEvent) -> None:
         )
 
         self.set_tls_secret(internal, Config.TLS.SECRET_CSR_LABEL, new_csr.decode("utf-8"))
+        self.set_waiting_for_cert_to_update(waiting=True, internal=internal)
 
-    def _get_sans(self) -> List[str]:
+    def get_new_sans(self) -> dict[str, list[str]]:
         """Create a list of DNS names for a MongoDB unit.
 
         Returns:
             A list representing the hostnames of the MongoDB unit.
         """
         unit_id = self.charm.unit.name.split("/")[1]
-        return [
-            f"{self.charm.app.name}-{unit_id}",
-            socket.getfqdn(),
-            f"{self.charm.app.name}-{unit_id}.{self.charm.app.name}-endpoints",
-            str(self.charm.model.get_binding(self.peer_relation).network.bind_address),
-            "localhost",
-        ]
+
+        sans = {
+            SANS_DNS_KEY: [
+                f"{self.charm.app.name}-{unit_id}",
+                socket.getfqdn(),
+                "localhost",
+                f"{self.charm.app.name}-{unit_id}.{self.charm.app.name}-endpoints",
+            ],
+            SANS_IPS_KEY: [
+                str(self.charm.model.get_binding(self.peer_relation).network.bind_address)
+            ],
+        }
+
+        if self.charm.is_role(Config.Role.MONGOS) and self.charm.is_external_client:
+            sans[SANS_IPS_KEY].append(
+                self.charm.get_ext_mongos_host(self.charm.unit, incl_port=False)
+            )
+
+        return sans
+
+    def get_current_sans(self, internal: bool) -> dict[str, list[str]] | None:
+        """Gets the current SANs for the unit cert."""
+        # if unit has no certificates do not proceed.
+        if not self.is_tls_enabled(internal=internal):
+            return
+
+        pem_file = self.get_tls_secret(internal, Config.TLS.SECRET_CERT_LABEL)
+
+        try:
+            cert = x509.load_pem_x509_certificate(pem_file.encode(), default_backend())
+            sans = cert.extensions.get_extension_for_class(x509.SubjectAlternativeName).value
+            sans_ip = [str(san) for san in sans.get_values_for_type(x509.IPAddress)]
+            sans_dns = [str(san) for san in sans.get_values_for_type(x509.DNSName)]
+        except x509.ExtensionNotFound:
+            sans_ip = []
+            sans_dns = []
+
+        return {SANS_IPS_KEY: sorted(sans_ip), SANS_DNS_KEY: sorted(sans_dns)}
 
     def get_tls_files(self, internal: bool) -> Tuple[Optional[str], Optional[str]]:
         """Prepare TLS files in special MongoDB way.
@@ -356,3 +410,23 @@ def _get_subject_name(self) -> str:
             return self.charm.get_config_server_name() or self.charm.app.name
 
         return self.charm.app.name
+
+    def is_set_waiting_for_cert_to_update(
+        self,
+        internal: bool = False,
+    ) -> bool:
+        """Returns True if we are waiting for a cert to update."""
+        scope = "int" if internal else "ext"
+        label_name = f"{scope}-{WAIT_CERT_UPDATE}"
+
+        return json.loads(self.charm.unit_peer_data.get(label_name, "false"))
+
+    def set_waiting_for_cert_to_update(
+        self,
+        waiting: bool,
+        internal: bool,
+    ) -> None:
+        """Sets a boolean indicator, for whether or not we are waiting for a cert to update."""
+        scope = "int" if internal else "ext"
+        label_name = f"{scope}-{WAIT_CERT_UPDATE}"
+        self.charm.unit_peer_data[label_name] = json.dumps(waiting)

src/charm.py

@@ -523,6 +523,11 @@ def unit_host(self, unit: Unit) -> str:
         else:
             raise ApplicationHostNotFoundError
 
+    @property
+    def db_initialised(self) -> bool:
+        """Proxy for mongos_initialised, since some libs rely on db_initialised."""
+        return self.mongos_initialised
+
     @property
     def mongos_initialised(self) -> bool:
         """Check if mongos is initialised."""