Preparing the master host operating system

Use this procedure to prepare a RHEL/CentOS host as a Control Center master host.
  1. Log in to the candidate master host as root, or as a user with superuser privileges.
  2. Disable the firewall, if necessary.
    This step is required for installation but not for deployment. For more information, refer to the Control Center Planning Guide.
    1. Determine whether the firewalld service is enabled.
      systemctl status firewalld.service
      • If the result includes Active: inactive (dead), the service is disabled. Proceed to the next step.
      • If the result includes Active: active (running), the service is enabled. Perform the following substep.
    2. Disable the firewalld service.
      systemctl stop firewalld && systemctl disable firewalld
      On success, the preceding commands display messages similar to the following example:
      rm '/etc/systemd/system/dbus-org.fedoraproject.FirewallD1.service'
      rm '/etc/systemd/system/basic.target.wants/firewalld.service'
  3. Optional: Enable persistent storage for log files, if desired.
    By default, RHEL/CentOS systems store log data only in memory or in a ring buffer in the /run/log/journal directory. By performing this step, log data persists and can be saved indefinitely, if you implement log file rotation practices. For more information, refer to your operating system documentation.
    mkdir -p /var/log/journal && systemctl restart systemd-journald
  4. Enable and start the Dnsmasq package.
    The package facilitates networking among Docker containers.
    systemctl enable dnsmasq && systemctl start dnsmasq
    If name resolution in your environment relies solely on entries in /etc/hosts, configure dsnmasq so that containers can use the file:
    1. Open /etc/dnsmasq.conf with a text editor.
    2. Locate the line that starts with #domain-needed, and then make a copy of the line, immediately below the original.
    3. Remove the number sign character (#) from the beginning of the line.
    4. Locate the line that starts with #bogus-priv, and then make a copy of the line, immediately below the original.
    5. Remove the number sign character (#) from the beginning of the line.
    6. Locate the line that starts with #local=/localnet/, and then make a copy of the line, immediately below the original.
    7. Remove net, and then remove the number sign character (#) from the beginning of the line.
    8. Locate the line that starts with #domain=example.com, and then make a copy of the line, immediately below the original.
    9. Replace example.com with local, and then remove the number sign character (#) from the beginning of the line.
    10. Save the file, and then close the editor.
    11. Restart the dnsmasq service.
      systemctl restart dnsmasq
  5. Add the required hostnames and IP addresses of both the primary and the secondary node to the /etc/hosts file.

    For a dual-NIC system, replace each variable name with the values designated for each node, and replace example.com with the domain name of your organization:

    echo "Primary-Public-IP Primary-Public-Name.example.com \
      Primary-Public-Name" >> /etc/hosts
    echo "Primary-Private-IP Primary-Private-Name.example.com \
      Primary-Private-Name" >> /etc/hosts
    echo "Secondary-Public-IP Secondary-Public-Name.example.com \
      Secondary-Public-Name" >> /etc/hosts
    echo "Secondary-Private-IP Secondary-Private-Name.example.com \
      Secondary-Private-Name" >> /etc/hosts

    For a single-NIC system, replace each variable name with the values designated for each node, and replace example.com with the domain name of your organization:

    echo "Primary-Public-IP Primary-Public-Name.example.com \
      Primary-Public-Name" >> /etc/hosts
    echo "Secondary-Public-IP Secondary-Public-Name.example.com \
      Secondary-Public-Name" >> /etc/hosts
  6. Create a mount point for application data backups.
    The default mount point is /opt/serviced/var/backups. You can change the default by editing the SERVICED_BACKUPS_PATH variable in the Control Center configuration file.
    mkdir -p /opt/serviced/var/backups
  7. Create a mount point for Control Center internal services data.
    The default mount point is /opt/serviced/var/isvcs. You can change the default by editing the SERVICED_ISVCS_PATH variable in the Control Center configuration file.
    mkdir -p /opt/serviced/var/isvcs
  8. Remove file system signatures from the required storage areas.

    Replace each variable name with the path of each storage area:

    wipefs -a Isvcs-Storage
    wipefs -a Metadata-Storage
    wipefs -a App-Data-Storage
  9. Reboot the host.
    reboot