[DPE-6572] Add wal_keep_size config option (#799)

* Add wal_keep_size config option

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

* Remove parameter addition

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

* Reset durability_wal_keep_size value to PG default

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

---------

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

Author: marceloneppel

config.yaml

@@ -32,6 +32,12 @@ options:
       crashes and there are replicas.
     type: string
     default: "on"
+  durability_wal_keep_size:
+    description: |
+      Sets the minimum size of the WAL file to be kept for the replication.
+      Allowed values are: from 0 to 2147483647.
+    type: int
+    default: 4096
   experimental_max_connections:
     type: int
     description: |

src/charm.py

@@ -1919,6 +1919,7 @@ def update_config(self, is_creating_backup: bool = False, no_peers: bool = False
         self._patroni.bulk_update_parameters_controller_by_patroni({
             "max_connections": max_connections,
             "max_prepared_transactions": self.config.memory_max_prepared_transactions,
+            "wal_keep_size": self.config.durability_wal_keep_size,
         })
 
         self._handle_postgresql_restart_need(enable_tls)

src/config.py

@@ -23,6 +23,7 @@ class CharmConfig(BaseConfigModel):
     connection_statement_timeout: int | None
     cpu_parallel_leader_participation: bool | None
     durability_synchronous_commit: str | None
+    durability_wal_keep_size: int | None
     experimental_max_connections: int | None
     instance_default_text_search_config: str | None
     instance_max_locks_per_transaction: int | None
@@ -205,6 +206,15 @@ def durability_synchronous_commit_values(cls, value: str) -> str | None:
 
         return value
 
+    @validator("durability_wal_keep_size")
+    @classmethod
+    def durability_wal_keep_size_values(cls, value: int) -> int | None:
+        """Check durability_wal_keep_size config option is between 0 and 2147483647."""
+        if value < 0 or value > 2147483647:
+            raise ValueError("Value is not between 0 and 2147483647")
+
+        return value
+
     @validator("instance_password_encryption")
     @classmethod
     def instance_password_encryption_values(cls, value: str) -> str | None:

tests/integration/test_db_admin.py

@@ -44,7 +44,7 @@ async def test_landscape_scalable_bundle_db(ops_test: OpsTest, charm: str) -> No
         application_name=DATABASE_APP_NAME,
         num_units=DATABASE_UNITS,
         base=CHARM_BASE,
-        config={"profile": "testing"},
+        config={"durability_wal_keep_size": 0, "profile": "testing"},
     )
 
     # Deploy and test the Landscape Scalable bundle (using this PostgreSQL charm).