plugin_sysctl.py: sysctl configs apply order

[alexeyantropov]

This block https://github.com/redhat-performance/tuned/blob/master/tuned/plugins/plugin_sysctl.py#L119-L123 applies configuration files in an unexpected order. At the first it applies override values from the sysctl.d drop-in directory, and at the last it applies values from main sysctl.conf config.

I reckon it's wrong. In the general case sysctl.conf has only default values and files from sysctl.d/*.conf have some custom values. However tuned (re)start breaks this drop-in approach and custom values are rewritten by the default values from the main config.

For example, it could be net.ipv4.ip_forward=1 in /etc/sysctl.d/foo.conf and net.ipv4.ip_forward=0 in /etc/sysctl.conf for virtualization systems like lxc, docker, kvm. After tuned (re)start virtual machines will be lost.

[alexeyantropov]

Ping?

[alexeyantropov]

Hello there! How about this issue? Is anybody alive here?

[yarda]

Although I think it's systemd fault and other tools, especially sysctl, which we took as the standard for the implementation, do it the same way, we will probably add some workaround for it.

There is downstream Red Hat bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2213614

[alexeyantropov]

Thx for the answer, got it