From 13d4dc9c859536f0da2991e8e3df33193242cce4 Mon Sep 17 00:00:00 2001
From: shayancanonical <99665202+shayancanonical@users.noreply.github.com>
Date: Sun, 31 Mar 2024 14:59:57 -0400
Subject: [PATCH] Create config for database name (#27)

* Create config for database name

* Address lint warnings
---
 config.yaml                   |  4 ++++
 src/charm.py                  | 23 ++++++++++++++++++-----
 src/literals.py               |  1 -
 src/relations/legacy_mysql.py |  8 +++++---
 4 files changed, 27 insertions(+), 9 deletions(-)

diff --git a/config.yaml b/config.yaml
index cdf972a..f86068d 100644
--- a/config.yaml
+++ b/config.yaml
@@ -6,3 +6,7 @@ options:
     description: "Whether to auto start continuous writes on relation events."
     type: boolean
     default: true
+  database_name:
+    description: "Name of database to direct continuous writes to"
+    type: string
+    default: "continuous_writes_database"
diff --git a/src/charm.py b/src/charm.py
index aabe76b..ca40f6c 100755
--- a/src/charm.py
+++ b/src/charm.py
@@ -16,6 +16,7 @@
 from typing import Dict, Optional
 
 from charms.data_platform_libs.v0.data_interfaces import DatabaseRequires
+from ops import EventBase
 from ops.charm import ActionEvent, CharmBase
 from ops.main import main
 from ops.model import ActiveStatus, Relation, WaitingStatus
@@ -24,7 +25,6 @@
 from connector import MySQLConnector  # isort: skip
 from literals import (
     CONTINUOUS_WRITE_TABLE_NAME,
-    DATABASE_NAME,
     DATABASE_RELATION,
     LEGACY_MYSQL_RELATION,
     PEER,
@@ -45,6 +45,7 @@ def __init__(self, *args):
 
         # Charm events
         self.framework.observe(self.on.start, self._on_start)
+        self.framework.observe(self.on.config_changed, self._on_config_changed)
         self.framework.observe(self.on[PEER].relation_changed, self._on_peer_relation_changed)
         self.framework.observe(self.on.update_status, self._on_update_status)
 
@@ -75,7 +76,9 @@ def __init__(self, *args):
         )
 
         # Database related events
-        self.database = DatabaseRequires(self, "database", DATABASE_NAME)
+        self.database = DatabaseRequires(
+            self, relation_name="database", database_name=self.database_name
+        )
         self.framework.observe(
             getattr(self.database.on, "database_created"), self._on_database_created
         )
@@ -119,6 +122,11 @@ def unit_peer_data(self) -> Dict:
 
         return self._peers.data[self.unit]
 
+    @property
+    def database_name(self) -> str:
+        """Returns the database name for the continuous writes."""
+        return self.config["database_name"]
+
     @property
     def _database_config(self):
         """Returns the database config to use to connect to the MySQL cluster."""
@@ -144,7 +152,7 @@ def _database_config(self):
         config = {
             "user": username,
             "password": password,
-            "database": DATABASE_NAME,
+            "database": self.database_name,
         }
         if endpoints.startswith("file://"):
             config["unix_socket"] = endpoints[7:]
@@ -221,7 +229,7 @@ def _max_written_value(self) -> int:
 
         with MySQLConnector(self._database_config) as cursor:
             cursor.execute(
-                f"SELECT MAX(number) FROM `{DATABASE_NAME}`.`{CONTINUOUS_WRITE_TABLE_NAME}`;"
+                f"SELECT MAX(number) FROM `{self.database_name}`.`{CONTINUOUS_WRITE_TABLE_NAME}`;"
             )
             return cursor.fetchone()[0]
 
@@ -268,6 +276,10 @@ def _write_random_value(self) -> str:
     # ==============
     # Handlers
     # ==============
+    def _on_config_changed(self, event: EventBase) -> None:
+        """Handle config changes, especially database_name."""
+        logger.warning("Please unrelate and re-relate after updating the database_name config")
+
     def _on_start(self, _) -> None:
         """Handle the start event."""
         self.unit.set_workload_version("0.0.2")
@@ -275,6 +287,7 @@ def _on_start(self, _) -> None:
             self.unit.status = ActiveStatus()
         else:
             self.unit.status = WaitingStatus()
+        self.app_peer_data["initialized"] = "true"
 
     def _on_clear_continuous_writes_action(self, _) -> None:
         """Handle the clear continuous writes action event."""
@@ -284,7 +297,7 @@ def _on_clear_continuous_writes_action(self, _) -> None:
         self._stop_continuous_writes()
         with MySQLConnector(self._database_config) as cursor:
             cursor.execute(
-                f"DROP TABLE IF EXISTS `{DATABASE_NAME}`.`{CONTINUOUS_WRITE_TABLE_NAME}`;"
+                f"DROP TABLE IF EXISTS `{self.database_name}`.`{CONTINUOUS_WRITE_TABLE_NAME}`;"
             )
 
     def _on_start_continuous_writes_action(self, _) -> None:
diff --git a/src/literals.py b/src/literals.py
index 866ce08..2acbe5e 100644
--- a/src/literals.py
+++ b/src/literals.py
@@ -4,7 +4,6 @@
 """Test application literals."""
 
 CONTINUOUS_WRITE_TABLE_NAME = "data"
-DATABASE_NAME = "continuous_writes_database"
 DATABASE_RELATION = "database"
 LEGACY_MYSQL_RELATION = "mysql"  # MariaDB legacy relation
 PEER = "application-peers"
diff --git a/src/relations/legacy_mysql.py b/src/relations/legacy_mysql.py
index 5ce5ebc..6f3d737 100644
--- a/src/relations/legacy_mysql.py
+++ b/src/relations/legacy_mysql.py
@@ -5,7 +5,7 @@
 
 import logging
 
-from literals import DATABASE_NAME, LEGACY_MYSQL_RELATION
+from literals import LEGACY_MYSQL_RELATION
 from ops import Object, RelationChangedEvent
 from ops.model import BlockedStatus
 
@@ -59,8 +59,10 @@ def _on_relation_joined(self, event):
             return
 
         database_name = relation_data["database"]
-        if database_name != DATABASE_NAME:
-            logger.error(f"Database name must be set to `{DATABASE_NAME}`. Modify the test.")
+        if database_name != self.charm.database_name:
+            logger.error(
+                f"Database name must be set to `{self.charm.database_name}`. Modify the test."
+            )
             self.charm.unit.status = BlockedStatus("Wrong database name")
             return