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Before You Begin

What is Schema Manager

Schema Manager is a Kubernetes operator developed by AppsCode that implements multi-tenancy inside KubeDB provisioned database servers like MySQL, MariaDB, PosgreSQL and MongoDB etc. With Schema Manager one can create database into specific database server. An user will also be created with KubeVault and assigned to that database. Using the newly created user credential one can access the database and run operations into it. One may pass the database server reference, configuration, user access policy through a single yaml and Schema Manager will do all the task above mentioned. Schema Manager also allows initializing the database and restore snapshot while bootstrap.

How MongoDB Schema Manager Process Works

The following diagram shows how MongoDB Schema Manager process worked. Open the image in a new tab to see the enlarged version.

MongoDB Schema Mananger Diagram
Fig: Process of MongoDB Schema Manager

The process consists of the following steps:

  1. At first the user will deploy a MongoDBDatabase object.

  2. Once a MongoDBDatabase object is deployed to the cluster, the Schema Manager operator first verifies if it has the required permission to be able to interact with the referred database-server by checking Double-OptIn. After the Double-OptIn verification Schema Manager operator checks in the MongoDB server if the target database is already present or not. If the database already present there, then the MongoDBDatabase object will be immediately denied.

  3. Once everything is ok in the MongoDB server side, then the target database will be created and an entry for that will be entered in the kubedb_system database.

  4. Then Schema Manager operator creates a MongoDB Role.

  5. Vault operator always watches for a Database Role.

  6. Once Vault operator finds a Database Role, it creates a Secret for that Role.

  7. After this process, the Vault operator creates a User in the MongoDB server. The user gets all the privileges on our target database and its credentials are served with the Secret. The user credentials secret reference is patched with the MongoDBDatabase object yaml in the field.

  8. If there is any init script associated with the MongoDBDatabase object, it will be executed in this step with the Schema Manager operator.

  9. The user can also provide a snapshot reference for initialization. In that case Schema Manager operator fetches necessary appbinding, secrets, repository.

  10. Stash operator watches for a Restoresession.

  11. Once Stash operator finds a Restoresession, it Restores the targeted database with the Snapshot.

In the next doc, we are going to show a step by step guide of using MongoDB Schema Manager with KubeDB.