Migrate Charmed MLflow Version 1 to Version 2

This guide shows how to migrate Charmed MLflow version 1 to version 2. This guide assumes you are running the old Charmed MLflow stack version 1, which runs with MariaDB. With MLflow version 2, we only support the MySQL integration. This guide outlines how to move data from MariaDB to MySQL and how to migrate data from version 1 to version 2.1.1. Data from the object store doesn’t need to be migrated.


This guide assumes the following:

  1. You have deployed MLflow version 1 with MariaDB, MLflow server version 1.x, and MinIO.

  2. You have CLI access to the machine where the Juju controller is deployed (all commands will be executed from there).

MariaDB Backup

Install the mysqldump command:

sudo apt update
sudo apt install mysql-client

Backup the MariaDB database with the following command:

mysqldump --host=<mariadb-charm-ip-address> --user=root --password=root --column-statistics=0 --databases database > mlflow-db.sql

Deploy MySQL Charm

Deploy the MySQL charm, which is needed for MLflow v2:

juju deploy mysql-k8s --channel 8.0/beta --series jammy --trust


For MLflow version v.2.1, we deploy the 8.0/beta version of the charm. You may deploy a more up to date version in your case.

Please wait until the charm goes to active in juju status. Then run the following command to get the password for MySQL:

juju run-action mysql-k8s/0 get-password --wait

Adjust the Database Backup

Rename the database from database (used in MariaDB) to mlflow (used in MySQL):

sed 's/`database`/`mlflow`/g' mlflow-db.sql > mlflow-db-updated.sql

Rename any duplicate constraints as MySQL does not allow that. In practice, the only duplicate constraint we’ve encountered is CONSTRAINT_1. It has two occurrences. The first occurrence can be renamed to CONSTRAINT-1, for example:

sed -i '0,/`CONSTRAINT_1`/s//`CONSTRAINT-1`/' mlflow-db-updated.sql

You can do all the above modifications in the text editor of your choice if you prefer.

Move Database to MySQL

Install the MySQL CLI tool:

sudo apt update
sudo apt-get install mysql-shell

Connect to the MySQL charm:

mysql --user=root --host=<mysql-unit-ip> -p
# you will be prompted for password

Create the MySQL database called mlflow:


Leave the client with ctrl + D.

Move the updated database dump file to MySQL:

mysql -u root -p <mysql_password> mlflow <mlflow-db-updated.sql

Migrate MySQL Database

Install the MLflow Python client version 2.1.1:

pip install mlflow==2.1.1

Run the migration script against the MySQL mlflow database:

mlflow db upgrade mysql+pymysql://root:<mysql-password>@<mysql-ip>/mlflow

Update MLflow Server

Remove relations from the old MLflow server:

juju remove-relation mlflow-db:mysql mlflow-server:db
juju remove-relation minio mlflow-server

Update the MLflow server:

juju refresh mlflow-server --channel 2.1/edge

Create relations with MinIO and MySQL:

juju relate mysql-k8s mlflow-server
juju relate minio mlflow-server