diff --git a/api/core/model_manager.py b/api/core/model_manager.py
index d64db890f90f4c..8f55918e1ffb22 100644
--- a/api/core/model_manager.py
+++ b/api/core/model_manager.py
@@ -413,8 +413,9 @@ def __init__(self, tenant_id: str,
         for load_balancing_config in self._load_balancing_configs:
             if load_balancing_config.name == "__inherit__":
                 if not managed_credentials:
+                    # FIXME: Mutation to loop iterable `self._load_balancing_configs` during iteration
                     # remove __inherit__ if managed credentials is not provided
-                    self._load_balancing_configs.remove(load_balancing_config)
+                    self._load_balancing_configs.remove(load_balancing_config)  # noqa: B909
                 else:
                     load_balancing_config.credentials = managed_credentials
 
diff --git a/api/core/rag/datasource/keyword/keyword_base.py b/api/core/rag/datasource/keyword/keyword_base.py
index 02838cb1bd5254..15e416a9c6c486 100644
--- a/api/core/rag/datasource/keyword/keyword_base.py
+++ b/api/core/rag/datasource/keyword/keyword_base.py
@@ -42,7 +42,8 @@ def _filter_duplicate_texts(self, texts: list[Document]) -> list[Document]:
             doc_id = text.metadata['doc_id']
             exists_duplicate_node = self.text_exists(doc_id)
             if exists_duplicate_node:
-                texts.remove(text)
+                # FIXME: Mutation to loop iterable `texts` during iteration
+                texts.remove(text)  # noqa: B909
 
         return texts
 
diff --git a/api/core/rag/datasource/vdb/vector_base.py b/api/core/rag/datasource/vdb/vector_base.py
index 17768ab042dd93..e60008831eefaf 100644
--- a/api/core/rag/datasource/vdb/vector_base.py
+++ b/api/core/rag/datasource/vdb/vector_base.py
@@ -61,7 +61,8 @@ def _filter_duplicate_texts(self, texts: list[Document]) -> list[Document]:
             doc_id = text.metadata['doc_id']
             exists_duplicate_node = self.text_exists(doc_id)
             if exists_duplicate_node:
-                texts.remove(text)
+                # FIXME: Mutation to loop iterable `texts` during iteration
+                texts.remove(text)  # noqa: B909
 
         return texts
 
diff --git a/api/core/rag/datasource/vdb/vector_factory.py b/api/core/rag/datasource/vdb/vector_factory.py
index 256abd28afbe53..8bad9f6bd2f0c3 100644
--- a/api/core/rag/datasource/vdb/vector_factory.py
+++ b/api/core/rag/datasource/vdb/vector_factory.py
@@ -157,7 +157,8 @@ def _filter_duplicate_texts(self, texts: list[Document]) -> list[Document]:
             doc_id = text.metadata['doc_id']
             exists_duplicate_node = self.text_exists(doc_id)
             if exists_duplicate_node:
-                texts.remove(text)
+                # FIXME: Mutation to loop iterable `texts` during iteration
+                texts.remove(text)  # noqa: B909
 
         return texts
 
diff --git a/api/migrations/versions/8e5588e6412e_add_environment_variable_to_workflow_.py b/api/migrations/versions/8e5588e6412e_add_environment_variable_to_workflow_.py
new file mode 100644
index 00000000000000..ec2336da4dec71
--- /dev/null
+++ b/api/migrations/versions/8e5588e6412e_add_environment_variable_to_workflow_.py
@@ -0,0 +1,33 @@
+"""add environment variable to workflow model
+
+Revision ID: 8e5588e6412e
+Revises: 6e957a32015b
+Create Date: 2024-07-22 03:27:16.042533
+
+"""
+import sqlalchemy as sa
+from alembic import op
+
+import models as models
+
+# revision identifiers, used by Alembic.
+revision = '8e5588e6412e'
+down_revision = '6e957a32015b'
+branch_labels = None
+depends_on = None
+
+
+def upgrade():
+    # ### commands auto generated by Alembic - please adjust! ###
+    with op.batch_alter_table('workflows', schema=None) as batch_op:
+        batch_op.add_column(sa.Column('environment_variables', sa.Text(), server_default='{}', nullable=False))
+
+    # ### end Alembic commands ###
+
+
+def downgrade():
+    # ### commands auto generated by Alembic - please adjust! ###
+    with op.batch_alter_table('workflows', schema=None) as batch_op:
+        batch_op.drop_column('environment_variables')
+
+    # ### end Alembic commands ###
diff --git a/api/models/workflow.py b/api/models/workflow.py
index 30a6bef95d2221..df2269cd0fb6cc 100644
--- a/api/models/workflow.py
+++ b/api/models/workflow.py
@@ -121,9 +121,7 @@ class Workflow(db.Model):
     created_at = db.Column(db.DateTime, nullable=False, server_default=db.text('CURRENT_TIMESTAMP(0)'))
     updated_by = db.Column(StringUUID)
     updated_at = db.Column(db.DateTime)
-    # TODO: update this field to sqlalchemy column after frontend update.
-    _environment_variables = '{}'
-    # _environment_variables = db.Column('environment_variables', db.Text, nullable=False, server_default='{}')
+    _environment_variables = db.Column('environment_variables', db.Text, nullable=False, server_default='{}')
 
     @property
     def created_by_account(self):
diff --git a/api/services/model_load_balancing_service.py b/api/services/model_load_balancing_service.py
index c684c2862b9745..185c88c8bbadbf 100644
--- a/api/services/model_load_balancing_service.py
+++ b/api/services/model_load_balancing_service.py
@@ -133,8 +133,9 @@ def get_load_balancing_configs(self, tenant_id: str, provider: str, model: str,
                 # move the inherit configuration to the first
                 for i, load_balancing_config in enumerate(load_balancing_configs):
                     if load_balancing_config.name == '__inherit__':
-                        inherit_config = load_balancing_configs.pop(i)
-                        load_balancing_configs.insert(0, inherit_config)
+                        # FIXME: Mutation to loop iterable `load_balancing_configs` during iteration
+                        inherit_config = load_balancing_configs.pop(i)  # noqa: B909
+                        load_balancing_configs.insert(0, inherit_config)  # noqa: B909
 
         # Get credential form schemas from model credential schema or provider credential schema
         credential_schemas = self._get_credential_schema(provider_configuration)