Configure Linux systemd for workload management

Before you can configure workload management on Linux distributions running systemd, you must configure systemd to manage splunkd as a service by creating a unit file that defines a cgroup hierarchy.

The following diagram illustrates the cgroup hierarchy under systemd:

For more information, see cgroups.

You must configure cpu and memory cgroups for workload management on all search heads and indexers.

Configure systemd to manage splunkd as a service

There are two ways to configure systemd to manage splunkd as a service:

• Configure systemd manually.
• Configure systemd using the enable boot-start command.

Configuring systemd using enable boot-start requires Splunk Enterprise version 7.2.2 or later.

Permissions requirements for systemd

systemd has the following permissions requirements:

• Non-root users must have super user permissions to manually configure systemd on Linux.
• Non-root users must have super user permissions to run start, stop, restart commands under systemd.

For instructions on how to create a new user with super user permissions, see your Linux documentation. The specific steps can vary depending on the Linux distribution.

You must use sudo to run systemctl start|stop|restart. If you do not use sudo, you must authenticate. For example:

==== AUTHENTICATING FOR org.freedesktop.systemd1.manage-units ===
Authentication is required to manage system services or units.
Multiple identities can be used for authentication:
 1.  <username_1>
 2.  <username_2>
Choose identity to authenticate as (1-2): 2
Password: 
==== AUTHENTICATION COMPLETE ===

Configure systemd manually

Follow these steps to configure systemd to manage splunkd as a service:

1. Confirm that your Linux machine is running systemd. See Is Linux running systemd?
2. Before you create, delete, or modify the systemd unit file, you must stop splunkd:

   $SPLUNK_HOME/bin/splunk stop
   

3. If you enabled Splunk software to start at boot using enable boot-start, run disable boot-start to remove both the splunk init script from /etc/init.d and its symbolic links.

   sudo $SPLUNK_HOME/bin/splunk disable boot-start
   

4. Open the $SPLUNK_HOME/etc/splunk-launch.conf file and note the value of SPLUNK_SERVER_NAME. The default value is Splunkd.
5. In the /etc/systemd/system directory, create a unit file named <SPLUNK_SERVER_NAME>.service, such as Splunkd.service.

   You can change the SPLUNK_SERVER_NAME to any name you choose by directly editing the splunk-launch.conf file.

6. Add the following content to the <SPLUNK_SERVER_NAME>.service unit file:

   [Unit]
   After=network.target
   
   [Service]
   Type=simple
   Restart=always
   ExecStart=/home/<username>/splunk/bin/splunk _internal_launch_under_systemd
   LimitNOFILE=65536
   SuccessExitStatus=51 52
   RestartPreventExitStatus=51
   RestartForceExitStatus=52
   KillMode=mixed
   KillSignal=SIGINT
   TimeoutStopSec=10min
   User=<username>
   Delegate=true
   MemoryLimit=<value>
   CPUShares=1024
   PermissionsStartOnly=true
   ExecStartPost=/bin/bash -c "chown -R <username>:<username> /sys/fs/cgroup/cpu/system.slice/%n"
   ExecStartPost=/bin/bash -c "chown -R <username>:<username> /sys/fs/cgroup/memory/system.slice/%n"
   
   [Install]
   WantedBy=multi-user.target
   

   Regarding these lines in the unit file:

   ExecStartPost=/bin/bash -c "chown -R <username>:<username> /sys/fs/cgroup/cpu/system.slice/%n"
   ExecStartPost=/bin/bash -c "chown -R <username>:<username> /sys/fs/cgroup/memory/system.slice/%n"
   

   if a group does not exist on they system with the name <username>, the splunkd service will not start. To workaround this issue, manually update the unit file with the correct group name.

   The MemoryLimit value should be set to the total system memory available in bytes. The MemoryLimit value will not update if the total available system memory changes. To update the MemoryLimit value in the unit file, manually edit the unit file value and run the systemctl daemon-reload command to reload systemd.

   The following unit file properties are set specifically for Splunk workload management:
   Type=simple
Restart=always
Delegate=true
   Do not change these values unless you are familiar with systemd or receive guidance from Splunk support.

   Do not use the following unit file properties. These properties can cause splunkd to fail on restart.
   RemainAfterExit=yes
ExecStop
   

   For more information, see Systemd unit file properties.

7. Reload the unit file.

   sudo systemctl daemon-reload
   

8. Start splunkd as a systemd service.

   sudo systemctl start Splunkd.service
   

9. Verify that splunkd is running as a systemd service:

   sudo systemctl status <SPLUNK_SERVER_NAME>.service
   

   When you create the splunkd service, systemd creates corresponding CPU and Memory cgroups in these locations:

   CPU: /sys/fs/cgroup/cpu/system.slice/<SPLUNK_SERVER_NAME>.service
   Memory: /sys/fs/cgroup/memory/system.slice/<SPLUNK_SERVER_NAME>.service
   

10. For distributed deployments, repeat steps 1-9 on all search heads and indexers.

systemd unit file properties

The following table lists the unit file properties you must specify to run splunkd as a service under systemd:

Property	Expected Value
Restart	always
Type	simple
ExecStart	$SPLUNK_HOME/bin/splunk _internal_launch_under_systemd
ExecStartPost	chown -R <USER>:<GROUP of USER>/sys/fs/cgroup/<cpu or memory>/system.slice/%n"
Delegate	True
SuccessExitStatus	51 52
RestartPreventExitStatus	51
RestartForceExitStatus	52
RemainAfterExit	no (default)
MemoryLimit	Example: 12G
CPUShares	Example: 8192. (Allowed range is 2 to 262144. Default is 1024.)
User, Group	<Splunk Owner> <Splunk Group>

For more information on systemd unit file properties, see Service unit configuration.

Manage clusters under systemd

When managing an indexer cluster under systemd:

You must use the sudo command to start, stop, and restart the cluster master or individual peer nodes using systemctl start|stop|restart commands. You do not need sudo to perform a rolling restart using the splunk rolling-restart cluster-peers command, or to take a peer offline using the splunk offline command.

When managing a search head cluster under systemd:

You must use the sudo command to start, stop, and restart cluster members using systemctl start|stop|restart commands. You do not need sudo to perform a rolling restart using the splunk rolling-restart shcluster-members command, or to remove a cluster member using the splunk remove shcluster-members command.

Next step

After you set up cgroups on your Linux operating system, you can configure workload management in Splunk Enterprise. See Configure workload management.