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 local-as 65536
set protocols bgp neighbor 192.168.2.1 shutdown
commit
exit

Run operational commands

Unlike a normal configuration session, 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 languages

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 '192.0.2.3'"
print "set firewall group address-group somehosts address '203.0.113.55'"
#!/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) $@"
fi

Executing pre-hooks/post-hooks Scripts

VyOS has the ability to run custom scripts before and after each commit

The default directories where your custom Scripts should be located are:

/config/scripts/commit/pre-hooks.d   - Directory with scripts that run before
                                       each commit.

/config/scripts/commit/post-hooks.d  - Directory with scripts that run after
                                       each commit.

Scripts are run in alphabetical order. Their names must consist entirely of ASCII upper- and lower-case letters,ASCII digits, ASCII underscores, and ASCII minus-hyphens.No other characters are allowed.

Note

Custom scripts are not executed with root privileges (Use sudo inside if this is necessary).

A simple example is shown below, where the ops command executed in the post-hook script is “show interfaces”.

vyos@vyos# set interfaces ethernet eth1  address 192.0.2.3/24
vyos@vyos# commit
Codes: S - State, L - Link, u - Up, D - Down, A - Admin Down
Interface        IP Address                        S/L  Description
---------        ----------                        ---  -----------
eth0             198.51.100.10/24                  u/u
eth1             192.0.2.3/24                      u/u
eth2             -                                 u/u
eth3             -                                 u/u
lo               203.0.113.5/24                    u/u

Preconfig on boot

The /config/scripts/vyos-preconfig-bootup.script script is called on boot before the VyOS configuration during boot process.

Any modifications were done to work around unfixed bugs and implement enhancements that 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 before VyOS configuration is applied.
# Any modifications required to work around unfixed bugs or use
# services not available through the VyOS CLI system can be placed here.

Postconfig on boot

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

Any modifications were done to work around unfixed bugs and implement enhancements that 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.