RancherOS parses the Linux kernel boot cmdline to add any keys it understands to its configuration. This allows you to modify what cloud-init sources it will use on boot, to enable
rancher.debug logging, or to almost any other configuration setting.
There are two ways to set or modify persistent kernel parameters, in-place (editing the file and reboot) or during installation to disk.
To edit the kernel boot parameters of an already installed RancherOS system, use the new
sudo ros config syslinux editing command (uses
To activate this setting, you will need to reboot.
If you want to set the extra kernel parameters when you are Installing RancherOS to Disk please use the
$ sudo ros install -d /dev/sda --append "rancheros.autologin=tty1"
RancherOS v1.1.0 added a Syslinux boot menu, which allows you to temporarily edit the boot paramters, or to select “Debug logging”, “Autologin”, both “Debug logging & Autologin” and “Recovery Console”.
On desktop systems the Syslinux boot menu can be switched to graphical mode by adding
UI vesamenu.c32 to a new line in
sudo ros config syslinux to edit the file).
rancher.recovery=true will start a single user
root bash session as easily in the boot process, with no network, or persitent filesystem mounted. This can be used to fix disk problems, or to debug your system.
rancher.ssh.daemon=false (its enabled in the os-config) can be used to start your RancherOS with no sshd daemon. This can be used to further reduce the ports that your system is listening on.
rancher.debug=true will log everything to the console for debugging.
rancher.autologin=<tty...> will automatically log in the sepcified console - common values are
ttyAMA0 - depending on your platform.
RancherOS v1.1.0 added detection of Hypervisor, and then will try to download the a service called
<hypervisor>-vm-tools. This may cause boot speed issues, and so can be disabled by setting
RancherOS v1.2.0 added ability to configure docker-sys bridge, this can be used like this