Configuring NiFi Registry Metadata Stores in MySQL

MySQL provides the option to use an externally located database that supports high availability.

Perform the following steps to use MySQL:

Download the MySQL JDBC driver and place it somewhere accessible to NiFi Registry.
```
/path/to/drivers/mysql-connector-java-8.0.16.jar
```
Create a database inside MySQL (enter mysql shell using mysql -u root -p).
```
CREATE DATABASE nifi_registry;
```
Create a database user and grant privileges (for remote users, use nifireg'@'<IP-ADDRESS>, or nifireg'@'% for any remote host).
```
GRANT ALL PRIVILEGES ON nifi_registry.* TO 'nifireg'@'localhost' IDENTIFIED BY 'changeme';
```

Configure the database properties in nifi-registry.properties.

nifi.registry.db.url=jdbc:mysql://<MYSQL-HOSTNAME>/nifi_registry
nifi.registry.db.driver.class=com.mysql.cj.jdbc.Driver
nifi.registry.db.driver.directory=/path/to/drivers
nifi.registry.db.username=nifireg
nifi.registry.db.password=changeme