Red Hat Enterprise Linux (RHEL) 7 and CentOS 7

The following instructions show you how to prepare your hosts on Red Hat Enterprise Linux (RHEL) 7 or later and on CentOS 7 or later.

Install a supported Linux kernel

Elastic Cloud Enterprise requires 3.10 or higher. Before you proceed, update the OS, and reboot the system.

Note

Kernel-LT has a regression on 4.4.156. From the archive repository, install 4.4.155.

  1. Add the repository required to obtain the kernel:

    yum update
    reboot
  2. Add the required options to the kernel boot arguments:

    sudo /sbin/grubby --update-kernel=ALL --args='cgroup_enable=memory cgroup.memory=nokmem swapaccount=1'
  3. Enable the overlay kernel module:

    echo "overlay" | sudo tee -a /etc/modules-load.d/overlay.conf
  4. Refresh the dynamically generated grub2 configuration and configure grub to boot the newly installed kernel 3.10 or higher:

    sudo grub2-set-default 0
    sudo grub2-mkconfig -o /etc/grub2.cfg

Install Docker

Which version of Docker you install depends on whether you use Red Hat Enterprise Linux (RHEL) or CentOS.

RHEL

If you are using RHEL 7.5 or later, we recommend that you use Docker 1.13 included with your RHEL distribution:

  1. Follow the installation instructions provided by Red Hat.
  2. Follow the same Docker configuration steps as those for CentOS.

CentOS

If you are using CentOS, install Docker LTS version 18.09.2:

  1. Add the Docker repository:

    sudo tee /etc/yum.repos.d/docker.repo <<-'EOF'
    [dockerrepo]
    name=Docker Repository
    baseurl=https://download.docker.com/linux/centos/7/x86_64/stable
    enabled=1
    gpgcheck=1
    gpgkey=https://download.docker.com/linux/centos/gpg
    EOF
    
    sudo yum makecache fast
  2. Install the latest version of docker-ce:

    sudo yum install docker-ce-18.09.2*

Recommended: Set Up XFS quotas

Elastic Cloud Enterprise can run without XFS quotas, but they are required to support disk space quotas for Elasticsearch data directories. Some Linux distributions such as RHEL and CentOS already provide XFS as the default file system; however, quotas might be disabled.

Disk space quotas set a limit on the amount of disk space a cluster node can use. Currently, quotas are calculated by a static ratio of 1:32, which means that for every 1 GB of RAM a cluster is given, a cluster node is allowed to consume 32 GB of disk space.

Note

Using LVM, mdadm, or a combination of the two for block device management is possible, but the configuration is not covered here, nor is it provided as part of supporting Elastic Cloud Enterprise.

To set up XFS with quotas on a single, pre-partitioned block device named /dev/xvdg1:

  1. Format the partition:

    sudo mkfs.xfs /dev/xvdg1
  2. Create the /mnt/data/ directory as a mount point:

    sudo install -o $USER -g $USER -d -m 700 /mnt/data
  3. Modify the entry for the XFS volume in the /etc/fstab file to add pquota,prjquota. The default filesystem path used by Elastic Cloud Enterprise is /mnt/data.

    /dev/xvdg1      /mnt/data       xfs     defaults,nofail,x-systemd.automount,prjquota,pquota  0 2
  4. Regenerate the mount files:

    sudo systemctl daemon-reload
    sudo systemctl restart local-fs.target

Update the configurations settings

  1. Stop the Docker service:

    sudo systemctl stop docker
  2. If you plan to run Elasticsearch 5.0 and later: Update the /etc/sysctl.conf file to set the maximum number of mapped memory areas a process can have:

    echo "vm.max_map_count=262144" | sudo tee -a /etc/sysctl.conf
  3. For RHEL only: Verify that fs.may_detach_mounts is enabled:

    cat /proc/sys/fs/may_detach_mounts

    If the output of this command is not 1, you must enable the setting in order for Docker to cleanly remove containers:

    1. Update the /etc/sysctl.conf file to include this line:

      fs.may_detach_mounts = 1
  4. Verify that IPv4 forwarding is enabled:

    cat /proc/sys/net/ipv4/ip_forward

    If the output of this command is not 1, you must enable IPv4 forwarding so that Docker can work as expected:

    1. Update the /etc/sysctl.conf file to include this line:

      net.ipv4.ip_forward = 1
    2. Restart the network service:

      sudo service network restart
    3. Verify that the change is applied:

      cat /proc/sys/net/ipv4/ip_forward

      The output 1 indicates that IPv4 forwarding is turned on.

  5. Adjust the system limits.

    Add the following configuration values to the /etc/security/limits.conf file. These values are derived from our experience with the Elastic Cloud hosted offering and should be used for Elastic Cloud Enterprise as well.

    Tip

    If you are using a user name other than elastic, adjust the configuration values accordingly.

    *                soft    nofile         1024000
    *                hard    nofile         1024000
    *                soft    memlock        unlimited
    *                hard    memlock        unlimited
    elastic          soft    nofile         1024000
    elastic          hard    nofile         1024000
    elastic          soft    memlock        unlimited
    elastic          hard    memlock        unlimited
    root             soft    nofile         1024000
    root             hard    nofile         1024000
    root             soft    memlock        unlimited
  6. If you did not create the mount point earlier (if you did not set up XFS), create the /mnt/data/ directory as a mount point:

    sudo install -o $USER -g $USER -d -m 700 /mnt/data
  7. If you set up a new device with XFS earlier:

    1. Mount the block device (change the device name if you use a different device than /dev/xvdg1):

      sudo mount /dev/xvdg1
    2. Set the permissions on the newly mounted device:

      sudo chown $USER:$USER /mnt/data
  8. Create the /mnt/data/docker directory for the Docker service storage:

    sudo install -o $USER -g $USER -d -m 700 /mnt/data/docker
  9. Disable the firewalld service. The service is not compatible with Docker and interferes with the installation of ECE. You must disable firewalld before installing or reinstalling ECE.

    sudo systemctl disable firewalld

Configure the Docker daemon options

  1. Update the /etc/systemd/system/docker.service.d/docker.conf file. If the file path and file do not exist, create them.

    [Unit]
    Description=Docker Service
    After=multi-user.target
    
    [Service]
    ExecStart=
    ExecStart=/usr/bin/dockerd --data-root /mnt/data/docker --storage-driver=overlay --bip=172.17.42.1/16
  2. Apply the updated Docker daemon configuration:

    1. Reload the Docker daemon configuration:

      sudo systemctl daemon-reload
    2. Restart the Docker service:

      sudo systemctl restart docker
    3. Enable Docker to start on boot:

      sudo systemctl enable docker
  3. Enable your user to communicate with the Docker subsystem by adding it to the docker group:

    sudo usermod -aG docker $USER
  4. Recommended: Tune your network settings.

    Create a 70-cloudenterprise.conf file in the /etc/sysctl.d/ file path that includes these network settings:

    cat << SETTINGS | sudo tee /etc/sysctl.d/70-cloudenterprise.conf
    net.ipv4.tcp_max_syn_backlog=65536
    net.core.somaxconn=32768
    net.core.netdev_max_backlog=32768
    SETTINGS
  5. Pin the Docker version to ensure that the docker-ce package does not get upgraded:

    echo "exclude=docker-ce" | sudo tee -a /etc/yum.conf
  6. Reboot your system to ensure that all configuration changes take effect:

    sudo reboot
  7. After rebooting, verify that your Docker settings persist as expected:

    sudo docker info | grep Root

    If the command returns Docker Root Dir: /mnt/data/docker, then your changes were applied successfully and persist as expected.

    If the command returns Docker Root Dir: /var/lib/docker, then you need to troubleshoot the previous configuration steps until the Docker settings are applied successfully before continuing with the installation process. For more information, see Custom Docker daemon options in the Docker documentation.

  8. Repeat these steps on other hosts that you want to use with Elastic Cloud Enterprise or follow the steps in the next section to start installing Elastic Cloud Enterprise.