refactor(db-read_only): Track conn type in Database instance

frappe/__init__.py

@@ -279,7 +279,9 @@ def connect_replica():
 		user = local.conf.replica_db_name
 		password = local.conf.replica_db_password
 
-	local.replica_db = get_db(host=local.conf.replica_host, user=user, password=password, port=port)
+	local.replica_db = get_db(
+		host=local.conf.replica_host, user=user, password=password, port=port, read_only=True
+	)
 
 	# swap db connections
 	local.primary_db = local.db

frappe/database/__init__.py

@@ -39,17 +39,21 @@ def drop_user_and_database(db_name, root_login=None, root_password=None):
 		)
 
 
-def get_db(host=None, user=None, password=None, port=None):
+def get_db(host=None, user=None, password=None, port=None, read_only=False):
 	import frappe
 
 	if frappe.conf.db_type == "postgres":
 		import frappe.database.postgres.database
 
-		return frappe.database.postgres.database.PostgresDatabase(host, user, password, port=port)
+		return frappe.database.postgres.database.PostgresDatabase(
+			host, user, password, port=port, read_only=read_only
+		)
 	else:
 		import frappe.database.mariadb.database
 
-		return frappe.database.mariadb.database.MariaDBDatabase(host, user, password, port=port)
+		return frappe.database.mariadb.database.MariaDBDatabase(
+			host, user, password, port=port, read_only=read_only
+		)
 
 
 def setup_help_database(help_db_name):

frappe/database/database.py

@@ -52,12 +52,22 @@ class Database(object):
 	class InvalidColumnName(frappe.ValidationError):
 		pass
 
-	def __init__(self, host=None, user=None, password=None, ac_name=None, use_default=0, port=None):
+	def __init__(
+		self,
+		host=None,
+		user=None,
+		password=None,
+		ac_name=None,
+		use_default=0,
+		port=None,
+		read_only=False,
+	):
 		self.setup_type_map()
 		self.host = host or frappe.conf.db_host or "127.0.0.1"
 		self.port = port or frappe.conf.db_port or ""
 		self.user = user or frappe.conf.db_name
 		self.db_name = frappe.conf.db_name
+		self.read_only = read_only  # Uses READ ONLY connection if set
 		self._conn = None
 
 		if ac_name:

frappe/database/mariadb/database.py

@@ -133,12 +133,10 @@ class MariaDBConnectionUtil:
 			self.close_connection_pools()
 			return self.create_connection()
 
-		read_only = frappe.conf.read_from_replica and frappe.conf.replica_host
-
 		if frappe.local.site not in _SITE_POOLS:
-			site_pool = self.create_connection_pool(read_only=read_only)
+			site_pool = self.create_connection_pool()
 		else:
-			site_pool = self.get_connection_pool(read_only=read_only)
+			site_pool = self.get_connection_pool()
 
 		try:
 			conn = site_pool.get_connection()
@@ -165,26 +163,26 @@ class MariaDBConnectionUtil:
 					pass
 			_SITE_POOLS.pop(frappe.local.site, None)
 
-	def get_pool_name(self, read_only=False) -> str:
-		pool_type = "read-only" if read_only else "default"
+	def get_pool_name(self) -> str:
+		pool_type = "read-only" if self.read_only else "default"
 		return f"{frappe.local.site}-{pool_type}"
 
-	def get_connection_pool(self, read_only=False) -> "ConnectionPool":
+	def get_connection_pool(self) -> "ConnectionPool":
 		"""Return MariaDB connection pool object.
 
 		If `read_only` is True, return a read only pool.
 		"""
-		return _SITE_POOLS[frappe.local.site]["read_only" if read_only else "default"]
+		return _SITE_POOLS[frappe.local.site]["read_only" if self.read_only else "default"]
 
-	def create_connection_pool(self, read_only=False):
+	def create_connection_pool(self):
 		pool = mariadb.ConnectionPool(
-			pool_name=self.get_pool_name(read_only=read_only),
+			pool_name=self.get_pool_name(),
 			pool_size=_MAX_POOL_SIZE,
 			pool_reset_connection=False,
 		)
 		pool.set_config(**self.get_connection_settings())
 
-		if read_only:
+		if self.read_only:
 			_SITE_POOLS[frappe.local.site].read_only = pool
 		else:
 			_SITE_POOLS[frappe.local.site].default = pool