Command scripting

VyOS supports executing configuration and operational commands non-interactively from shell scripts.

To include VyOS-specific functions and aliases you need to source /opt/vyatta/etc/functions/script-template files at the top of your script.

#!/bin/vbash
source /opt/vyatta/etc/functions/script-template

exit

Run configuration commands

Configuration commands are executed just like from a normal config session.

For example, if you want to disable a BGP peer on VRRP transition to backup:

#!/bin/vbash
source /opt/vyatta/etc/functions/script-template

configure

set protocols bgp 65536 neighbor 192.168.2.1 shutdown

commit

exit

Run operational commands

Unlike a normal configuration sessions, all operational commands must be prepended with run, even if you haven’t created a session with configure.

#!/bin/vbash
source /opt/vyatta/etc/functions/script-template

run show interfaces

exit

Other script language

If you want to script the configs in a language other than bash you can have your script output commands and then source them in a bash script.

Here is a simple example:

#!/usr/bin/env python
print "delete firewall group address-group somehosts"
print "set firewall group address-group somehosts address '1.1.1.1'"
print "set firewall group address-group somehosts address '1.1.1.2'"
#!/bin/vbash
source /opt/vyatta/etc/functions/script-template

configure
source <(/config/scripts/setfirewallgroup.py)
commit

Executing Configuration Scripts

There is a pitfall when working with configuration scripts. It is tempting to call configuration scripts with “sudo” (i.e., temporary root permissions), because that’s the common way on most Linux platforms to call system commands.

On VyOS this will cause the following problem: After modifying the configuration via script like this once, it is not possible to manually modify the config anymore:

sudo ./myscript.sh # Modifies config
configure
set ... # Any configuration parameter
This will result in the following error message: Set failed
If this happens, a reboot is required to be able to edit the config manually again.

To avoid these problems, the proper way is to call a script with the vyattacfg group, e.g., by using the sg (switch group) command:

sg vyattacfg -c ./myscript.sh

To make sure that a script is not accidentally called without the vyattacfg group, the script can be safeguarded like this:

if [ "$(id -g -n)" != 'vyattacfg' ] ; then
    exec sg vyattacfg -c "/bin/vbash $(readlink -f $0) [email protected]"
fi

Postconfig on boot

The /config/scripts/vyos-postconfig-bootup.script script is called on boot after the VyOS configuration is fully applied.

Any modifications done to work around unfixed bugs and implement enhancements which are not complete in the VyOS system can be placed here.

The default file looks like this:

#!/bin/sh
# This script is executed at boot time after VyOS configuration is fully applied.
# Any modifications required to work around unfixed bugs
# or use services not available through the VyOS CLI system can be placed here.

Hint

For configuration/upgrade management issues, modification of this script should be the last option. Always try to find solutions based on CLI commands first.