Configure Linux systems running systemd

If your Linux system is running systemd, you must configure systemd to manage splunkd as a service by creating a unit file that defines a cgroup hierarchy.

The 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.

Splunk Enterprise 9.3 supports workload management on Linux cgroups v1 by default. Support for cgroups v2 is available for early access customers only. For more information, contact your Splunk account representative.

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 automatically using the splunk enable boot-start command.

System requirements

To enable workload management in Splunk Enterprise under systemd requires systemd version 219 or higher. For more information, see Linux operating system requirements.

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, and 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 specific Linux distribution.

You must use sudo to run splunk 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 ===

Alternatively, you can install polkit rules to allow non-root users to run start, stop, and restart operations under systemd without using sudo, when running the enable-boot-start command to configure the systemd service automatically. For more information, see Install polkit rules to elevate user permissions.

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 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 (text 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=/opt/splunk/bin/splunk _internal_launch_under_systemd
   KillMode=mixed
   KillSignal=SIGINT
   TimeoutStopSec=360
   LimitNOFILE=65536
   SuccessExitStatus=51 52
   RestartPreventExitStatus=51
   RestartForceExitStatus=52
   User=splunk
   Group=splunk
   Delegate=true
   CPUShares=1024
   MemoryLimit=<value>
   PermissionsStartOnly=true
   ExecStartPost=/bin/bash -c "chown -R splunk:splunk /sys/fs/cgroup/cpu/system.slice/%n"
   ExecStartPost=/bin/bash -c "chown -R splunk:splunk /sys/fs/cgroup/memory/system.slice/%n"
   
   [Install]
   WantedBy=multi-user.target
   

   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 on systemd unit file configuration settings, see Service unit configuration.

7. Reload the unit file.

   sudo systemctl daemon-reload
   

8. Start splunkd.

   sudo $SPLUNK_HOME/bin/splunk start
   

   This starts splunkd as a systemd service.

   Under systemd, splunk start|stop|restart commands are mapped to systemctl start|stop|restart commands.

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
   

   On Splunk Enterprise 8.0.0 or higher, on initial start of the splunkd service, the software checks the systemd environment, identifies the cgroup path, and automatically sets permissions for the cgroup directories.

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

Manage clusters under systemd

When managing an indexer cluster under systemd:

You must use the sudo command to start, stop, and restart the cluster manager node or individual peer nodes using splunk 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 splunk 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.

Upgrade considerations for systemd

Upgrade from 8.0.x to 8.1

If you configured Splunk Enterprise to run as a systemd service in version 8.0.x, upon upgrade to version 8.1, Splunk Enterprise automatically updates the existing Splunkd.service unit file with the following properties:

User
Group
ExecStartPost

Upgrade from 7.3.x or earlier to 8.0

If you configured Splunk Enterprise to run as a systemd service in version 7.3.x or lower, upon upgrade to version 8.0.0, Splunk Enterprise automatically updates the existing Splunkd.service unit file. For detailed information on these unit files changes, see Upgrade considerations for systemd in the Admin Manual.

Next step

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