Running a command in a State
For this illustration let's pretend that we want to execute the script/ root/ scripts/test.sh on systems with the nginx software loaded. To do this we can simply add the command into the nginx state file.
On the Salt Master edit the nginx/init.sls file
vi/ salt/ states/ base/ nginx/init.sls
Append the following
- run
- name/ root/ scripts/test.sh
The below entry will tell Salt to run the command named/ root/ scripts/test.sh every time the systems state is managed.
Using onlyif and unless
What if we only want to run the command when certain conditions are true? Well salt can handle that too. We can us the onlyif and unless options to tell Salt to only run the command if certain conditions are met.
Onlyif
Onlyif will execute the command only if the supplied command is true. In the below illustration we will only executetest.sh if the file exists.
illustration
test.sh
cmd
- run
- name/ root/ scripts/test.sh
- onlyif test- f/ root/ scripts/test.sh
Unless
While onlyif executes the named command if the supplied command returns true, unless will only execute the named command if the supplied command returns false. In this illustration we will execute the commandtest.sh only when the nginx configtest fails.
Illustration
cmd
- run
- name/ root/ scripts/test.sh
- unless/ usr/ sbin/ service nginx configtest
Stateful commands
If you want Salt to understand whether your script passed or failed you can do this by making the command stateful.
Adding stateful to the state file
In the state file we will tell Salt that the command is stateful by appending- stateful True.
illustration
- run
- name/ root/ scripts/test.sh
- unless/ usr/ sbin/ service nginx configtest
- stateful True
Adding state status to the script
Now that salt knows the command is “ stateful ” the script must also tell Salt what has changed and if it was successful or not. To do this you can append two lines at the end of the scripts output.
Illustration of a good run
echo""## This echos an empty line and is required
echo" changed = yes comment = ' I executed something and it changed'"
Illustration of a failed run
echo""## This echos an empty line and is required
echo" changed = no comment = ' I executed something and it didn't change'"
It's ok if your script also has other output. Salt will only be looking at the last two lines of output; so you must make sure that these lines are at the end. For further information about running commands in states check out the Saltstack cmd state docs.
