## Managed MariaDB Service

The Managed MariaDB Service offers a powerful and widely used relational database solution.
This service allows you to create and manage a replicated MariaDB cluster seamlessly.

## Deployment Details

This managed service is controlled by mariadb-operator, ensuring efficient management and seamless operation.

- Docs: https://mariadb.com/kb/en/documentation/
- GitHub: https://github.com/mariadb-operator/mariadb-operator

## HowTos

### How to switch master/slave replica

```bash
kubectl edit mariadb <instnace>
```
update:

```bash
spec:
  replication:
    primary:
      podIndex: 1
```

check status:

```bash
NAME        READY   STATUS    PRIMARY POD   AGE
<instance>  True    Running   app-db1-1     41d
```

### How to restore backup:

find snapshot:
```bash
restic -r s3:s3.example.org/mariadb-backups/database_name snapshots
```


restore:
```bash
restic -r s3:s3.example.org/mariadb-backups/database_name restore latest --target /tmp/
```

more details:
- https://blog.aenix.io/restic-effective-backup-from-stdin-4bc1e8f083c1

### Known issues

- **Replication can't be finished with various errors**
- **Replication can't be finished in case if `binlog` purged**

  Until `mariadbbackup` is not used to bootstrap a node by mariadb-operator (this feature is not inmplemented yet), follow these manual steps to fix it:
  https://github.com/mariadb-operator/mariadb-operator/issues/141#issuecomment-1804760231

- **Corrupted indicies**
  Sometimes some indecies can be corrupted on master replica, you can recover them from slave:

  ```bash
  mysqldump -h <slave> -P 3306 -u<user> -p<password> --column-statistics=0 <database> <table> ~/tmp/fix-table.sql
  mysql -h <master> -P 3306 -u<user> -p<password> <database> < ~/tmp/fix-table.sql
  ```

## Parameters

### Common parameters

| Name               | Description                                                                                                                       | Type       | Value   |
| ------------------ | --------------------------------------------------------------------------------------------------------------------------------- | ---------- | ------- |
| `replicas`         | Number of MariaDB replicas.                                                                                                       | `int`      | `2`     |
| `resources`        | Explicit CPU and memory configuration for each MariaDB replica. When omitted, the preset defined in `resourcesPreset` is applied. | `object`   | `{}`    |
| `resources.cpu`    | CPU available to each replica.                                                                                                    | `quantity` | `""`    |
| `resources.memory` | Memory (RAM) available to each replica.                                                                                           | `quantity` | `""`    |
| `resourcesPreset`  | Default sizing preset used when `resources` is omitted.                                                                           | `string`   | `nano`  |
| `size`             | Persistent Volume Claim size available for application data.                                                                      | `quantity` | `10Gi`  |
| `storageClass`     | StorageClass used to store the data.                                                                                              | `string`   | `""`    |
| `external`         | Enable external access from outside the cluster.                                                                                  | `bool`     | `false` |


### Application-specific parameters

| Name                             | Description                              | Type                | Value |
| -------------------------------- | ---------------------------------------- | ------------------- | ----- |
| `users`                          | Users configuration map.                 | `map[string]object` | `{}`  |
| `users[name].password`           | Password for the user.                   | `string`            | `""`  |
| `users[name].maxUserConnections` | Maximum number of connections.           | `int`               | `0`   |
| `databases`                      | Databases configuration map.             | `map[string]object` | `{}`  |
| `databases[name].roles`          | Roles assigned to users.                 | `object`            | `{}`  |
| `databases[name].roles.admin`    | List of users with admin privileges.     | `[]string`          | `[]`  |
| `databases[name].roles.readonly` | List of users with read-only privileges. | `[]string`          | `[]`  |


### Backup parameters

| Name                     | Description                                     | Type     | Value                                                  |
| ------------------------ | ----------------------------------------------- | -------- | ------------------------------------------------------ |
| `backup`                 | Backup configuration.                           | `object` | `{}`                                                   |
| `backup.enabled`         | Enable regular backups (default: false).        | `bool`   | `false`                                                |
| `backup.s3Region`        | AWS S3 region where backups are stored.         | `string` | `us-east-1`                                            |
| `backup.s3Bucket`        | S3 bucket used for storing backups.             | `string` | `s3.example.org/mysql-backups`                         |
| `backup.schedule`        | Cron schedule for automated backups.            | `string` | `0 2 * * *`                                            |
| `backup.cleanupStrategy` | Retention strategy for cleaning up old backups. | `string` | `--keep-last=3 --keep-daily=3 --keep-within-weekly=1m` |
| `backup.s3AccessKey`     | Access key for S3 authentication.               | `string` | `<your-access-key>`                                    |
| `backup.s3SecretKey`     | Secret key for S3 authentication.               | `string` | `<your-secret-key>`                                    |
| `backup.resticPassword`  | Password for Restic backup encryption.          | `string` | `<password>`                                           |


## Parameter examples and reference

### resources and resourcesPreset

`resources` sets explicit CPU and memory configurations for each replica.
When left empty, the preset defined in `resourcesPreset` is applied.

```yaml
resources:
  cpu: 4000m
  memory: 4Gi
```

`resourcesPreset` sets named CPU and memory configurations for each replica.
This setting is ignored if the corresponding `resources` value is set.

| Preset name | CPU    | memory  |
|-------------|--------|---------|
| `nano`      | `250m` | `128Mi` |
| `micro`     | `500m` | `256Mi` |
| `small`     | `1`    | `512Mi` |
| `medium`    | `1`    | `1Gi`   |
| `large`     | `2`    | `2Gi`   |
| `xlarge`    | `4`    | `4Gi`   |
| `2xlarge`   | `8`    | `8Gi`   |

### users

```yaml
users:
  user1:
    maxUserConnections: 1000
    password: hackme
  user2:
    maxUserConnections: 1000
    password: hackme
```


### databases

```yaml
databases:
  myapp1:
    roles:
      admin:
      - user1
      readonly:
      - user2
```