How-to: Test Linux kernel swapiness
Overview
This example illustrates how the SSH plugin can be used to test the kernel swap policy in Linux (specifically the Linux variants Centos and Red Hat).
This example modifies the How-to: Configure Linux kernel swapiness example, which illustrated how to define resources for enabling usage of the SSH plugin, define credentials for authentication and create the module which configured the Linux kernel swappiness policy.
Part of the default configuration
This example is included in the default configuration created by Pineapple, so there is no need to create it by hand.
Define module
The created module in the How-to: Configure Linux kernel swapiness example was named ssh-001-configure-wm-swapiness. In this example we will start off with a copy of that module, but naming it ssh-001-test-wm-swapiness and modifies the model to test instead of configuring.
Modify the model
Replace the lines:
<!-- set kernel swappiness --> <shp:execute command="sudo sysctl -w vm.swappiness=0" />
with:
<!-- test kernel swappiness --> <shp:assert-equals command="cat /proc/sys/vm/swapiness" expected-value="0"/>
The result being:
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<mmd:models xmlns:mmd="http://pineapple.dev.java.net/ns/module_model_1_0"
xmlns:shp="http://pineapple.dev.java.net/ns/plugin/ssh_1_0" >
<mmd:model target-resource="regex:ssh-node.*">
<mmd:content>
<shp:ssh>
<!-- test kernel swappiness -->
<shp:assert-equals command="cat /proc/sys/vm/swapiness" expected-value="0"/>
</shp:ssh>
</mmd:content>
</mmd:model>
</mmd:models>
The configuration details
The assert-equals command extends the execute command with the extension that it executes a shell command and then asserts whether the output from standard out matches the expected values. The assert-equals commands asserts that the output in standard out is contains the expected value.