install icinga2 with mysql db (under ubuntu 18.04)

curl -sSL https://packages.icinga.com/icinga.key | sudo apt-key add -
echo "deb https://packages.icinga.com/ubuntu icinga-bionic main" | sudo tee /etc/apt/sources.list.d/icinga.list
sudo apt install icinga2 icingaweb2 icinga2-ido-mysql    

create a database

mysql -u root -p
CREATE DATABASE icinga2_db;
GRANT ALL PRIVILEGES on icinga2_db.* to 'icinga2_user'@'localhost' identified by 'StrongPassword';
FLUSH PRIVILEGES;
quit

create mysql conf file

sudo nano /etc/icinga2/features-available/ido-mysql.conf

/**
 * The db_ido_mysql library implements IDO functionality
 * for MySQL.
 */

library "db_ido_mysql"

object IdoMysqlConnection "ido-mysql" {
  user = "icinga2_user",
  password = "StrongPassword",
  host = "localhost",
  database = "icinga2_db"
}

enable mysql feature

sudo icinga2 feature enable command  ido-mysql

restart icinga2

sudo systemctl restart icinga2

create token

sudo icingacli setup token create