Salt custom grains

Question

I am trying to write custom grains. I put this code in /etc/salt/grains

#!/usr/bin/env python
def function():
    grains = {}
    grains['test'] = "test"
    return grains

and to test it I created this script:

import salt.config
import salt.loader
__opts__ = salt.config.minion_config('/etc/salt/minion')
__grains__ = salt.loader.grains(__opts__)
test = __grains__['test']
print test

I've got this error:

dirs = __grains__['test']
KeyError: 'test'

What's wrong with this ?

Answer 1

/etc/salt/grains is where salt stores grains set by salt targetid grains.setval and friends. It is a flat, static yaml file.

Custom grains via python go in /srv/salt/_grains, and are then synced to minions with salt \* saltutil.sync_grains. This is where you should put your python script.

Here is an example similar to your code with logging and verification:

$ cat /srv/salt/_grains/spam.py 
#!/usr/bin/env python
import logging
log = logging.getLogger(__name__)

def function():
    log.trace('Setting grains["spam"] to "eggs"')
    grains = {}
    grains['spam'] = "eggs"
    return grains

$ sudo salt lead saltutil.sync_grains
lead:
    - grains.spam

$ sudo salt-call grains.item spam -l trace 2>&1 \
  | egrep '^local|spam'
[TRACE   ] Added spam.function to grain
[TRACE   ] Setting grains["spam"] to "eggs"
local:
  spam: eggs

$ cat /tmp/spam_taster.py 
#!/usr/bin/env python
import salt.config
import salt.loader
__opts__ = salt.config.minion_config('/etc/salt/minion')
__grains__ = salt.loader.grains(__opts__)
spam = __grains__['spam']
print spam

$ python /tmp/spam_taster.py 
eggs