tests/prometheus-exporters: add test for mysqld exporter

      '';

    };

    mysqld = {

      exporterConfig = {

        enable = true;

        runAsLocalSuperUser = true;

        configFile = pkgs.writeText "test-prometheus-exporter-mysqld-config.my-cnf" ''

          [client]

          user = exporter

          password = snakeoilpassword

        '';

      };

      metricProvider = {

        services.mysql = {

          enable = true;

          package = pkgs.mariadb;

          initialScript = pkgs.writeText "mysql-init-script.sql" ''

            CREATE USER 'exporter'@'localhost'

            IDENTIFIED BY 'snakeoilpassword'

            WITH MAX_USER_CONNECTIONS 3;

            GRANT PROCESS, REPLICATION CLIENT, SLAVE MONITOR, SELECT ON *.* TO 'exporter'@'localhost';

          '';

        };

      };

      exporterTest = ''

        wait_for_unit("prometheus-mysqld-exporter.service")

        wait_for_open_port(9104)

        wait_for_unit("mysql.service")

        succeed("curl -sSf http://localhost:9104/metrics | grep 'mysql_up 1'")

        systemctl("stop mysql.service")

        succeed("curl -sSf http://localhost:9104/metrics | grep 'mysql_up 0'")

        systemctl("start mysql.service")

        wait_for_unit("mysql.service")

        succeed("curl -sSf http://localhost:9104/metrics | grep 'mysql_up 1'")

      '';

    };

    nextcloud = {

      exporterConfig = {

        enable = true;