SUSE Linux Enterprise Server (SLES) 12 SP5

The following instructions show you how to prepare your hosts on SLES 12 SP5.

If you want to install Elastic Cloud Enterprise on your own hosts, the steps for preparing your hosts can take a bit of time. There are two ways you can approach this:

Think like a minimalist: Install the correct version of Docker on hosts that meet the prerequisites for Elastic Cloud Enterprise, then skip ahead and install Elastic Cloud Enterprise. Be aware that some checks during the installation can fail with this approach, which will mean doing further host preparation work before retrying the installation.
Cover your bases: If you want to make absolutely sure that your installation of Elastic Cloud Enterprise can succeed on hosts that meet the prerequisites, or if any of the checks during the installation failed previously, run through the full preparation steps in this section and then and install Elastic Cloud Enterprise. You’ll do a bit more work now, but life will be simpler later on.

Regardless of which approach you take, the steps in this section need to be performed on every host that you want to use with Elastic Cloud Enterprise.

Install Docker version docker-19.03.14_ce

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Install the correct version of the docker package:
```
sudo zypper install -y docker-19.03.14_ce
```

Set up XFS on SLES

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XFS is 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. On SLES 12, you need to set up an XFS file system and have quotas enabled.

Disk space quotas set a limit on the amount of disk space an Elasticsearch 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.

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.

You must use XFS and have quotas enabled on all allocators, otherwise disk usage won’t display correctly.

Example: Set up XFS on a single, pre-partitioned block device named /dev/xvdg1.

Format the partition:
```
sudo mkfs.xfs /dev/xvdg1
```

Create the /mnt/data/ directory as a mount point:

sudo install -o $USER -g $USER -d -m 700 /mnt/data

Add an entry to the /etc/fstab file for the new XFS volume. The default filesystem path used by Elastic Cloud Enterprise is /mnt/data.
```
/dev/xvdg1	/mnt/data	xfs	defaults,pquota,prjquota,x-systemd.automount  0 0
```
Regenerate the mount files:
```
sudo mount -a
```

Update the configurations settings

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Stop the Docker service:
```
sudo systemctl stop docker
```
Enable cgroup accounting for memory and swap space.
1. In the /etc/default/grub file, ensure that the GRUB_CMDLINE_LINUX= variable includes these values:
```
cgroup_enable=memory swapaccount=1 cgroup.memory=nokmem
```
2. Update your Grub configuration:
```
sudo update-bootloader
```

Configure kernel parameters

cat <<EOF | sudo tee -a /etc/sysctl.conf
# Required by Elasticsearch 5.0 and later
vm.max_map_count=262144
# enable forwarding so the Docker networking works as expected
net.ipv4.ip_forward=1
# Decrease the maximum number of TCP retransmissions to 5 as recommended for Elasticsearch TCP retransmission timeout.
# See https://www.elastic.co/guide/en/elasticsearch/reference/current/system-config-tcpretries.html
net.ipv4.tcp_retries2=5
# Make sure the host doesn't swap too early
vm.swappiness=1
EOF

The net.ipv4.tcp_retries2 setting applies to all TCP connections and affects the reliability of communication with systems other than Elasticsearch clusters too. If your clusters communicate with external systems over a low quality network then you may need to select a higher value for net.ipv4.tcp_retries2.

Apply the settings:

sudo sysctl -p
sudo service network restart

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.

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
elastic          soft    nproc          unlimited
elastic          hard    nproc          unlimited
root             soft    nofile         1024000
root             hard    nofile         1024000
root             soft    memlock        unlimited

NOTE: This step is optional if the docker registry doesn’t require authentication.

Authenticate the elastic user to pull images from the docker registry you use, by creating the file /home/elastic/.docker/config.json. This file needs to be owned by the elastic user. If you are using a user name other than elastic, adjust the path accordingly.

Example: In case you use docker.elastic.co, the file content looks like as follows:
```
{
 "auths": {
   "docker.elastic.co": {
     "auth": "<auth-token>"
   }
 }
}
```
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
```
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
```
Create the /mnt/data/docker directory for the Docker service storage:
```
sudo install -o $USER -g $USER -d -m 700 /mnt/data/docker
```

Configure the Docker daemon options

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You can specify --log-opt max-size and --log-opt max-file to define the Docker daemon containers log rotation.

Update /etc/sysconfig/docker. If the file path and file do not exist, create them first.

Docker version 18.09.9

## Path           : System/Management
## Description    : Extra cli switches for docker daemon
## Type           : string
## Default        : ""
## ServiceRestart : docker
#
DOCKER_OPTS="-H unix:///run/docker.sock -g /mnt/data/docker --storage-driver=overlay2 --bip=172.17.42.1/16 --raw-logs --log-opt max-size=500m --log-opt max-file=10 --icc=false"

Apply the updated Docker daemon configuration:

Reload the Docker daemon configuration:
```
sudo systemctl daemon-reload
```
Restart the Docker service:
```
sudo systemctl restart docker
```
Enable Docker to start on boot:
```
sudo systemctl enable docker
```
Enable your user to communicate with the Docker subsystem by adding it to the docker group:
```
sudo usermod -aG docker $USER
```

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
net.ipv4.tcp_keepalive_time=1800
net.netfilter.nf_conntrack_tcp_timeout_established=7200
net.netfilter.nf_conntrack_max=262140
SETTINGS

Ensure settings in /etc/sysctl.d/*.conf are applied on boot

SCRIPT_LOCATION="/var/lib/cloud/scripts/per-boot/00-load-sysctl-settings"
sudo sh -c "cat << EOF > ${SCRIPT_LOCATION}
#!/bin/bash

set -x

lsmod | grep ip_conntrack || modprobe ip_conntrack

sysctl --system
EOF
"
sudo chmod +x ${SCRIPT_LOCATION}

Reboot your system to ensure that all configuration changes take effect:
```
sudo reboot
```
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, check Custom Docker daemon options in the Docker documentation.
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.

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