Sometimes debugging with
print() and extra logs sprinkled everywhere is not
the best strategy.
IPython is a helpful debug tool that has an interactive python environment which can be embedded in python programs.
First the system will require IPython to be installed.
apt-get install ipython
# Arch Linux
pacman -Syu ipython2
# RHEL/CentOS (via EPEL)
yum install python-ipython
Now, in the troubling python module, add the following line at a location where the debugger should be started:
test = 'test123'
import IPython; IPython.embed_kernel()
After running a Salt command that hits that line, the following will show up in the log file:
[CRITICAL] To connect another client to this kernel, use:
[IPKernelApp] --existing kernel-31271.json
Now on the system that invoked
embed_kernel, run the following command from
# NOTE: use ipython2 instead of ipython for Arch Linux
ipython console --existing
This provides a console that has access to all the vars and functions, and even supports tab-completion.
To exit IPython and continue running Salt, press
Ctrl-d to logout.
These are things that may be defined by the module to influence various things.
grains and proxy modules
__proxyenabled__ as a list containing the names of the proxy types that the module supports.
Salt provides several special "dunder" dictionaries as a convenience for Salt
development. These include
others. This document will describe each dictionary and detail where they exist
and what information and/or functionality they provide.
The following dunder dictionaries are always defined, but may be empty
Defined in: All modules
__opts__ dictionary contains all of the options passed in the
configuration file for the master or minion.
In many places in salt, instead of pulling raw data from the __opts__
dict, configuration data should be pulled from the salt get functions
such as config.get, aka -
The get functions also allow for dict traversal via the : delimiter.
Consider using get functions whenever using
__grains__ (when using grains for configuration data)
The configuration file data made available in the
__opts__ dictionary is the
configuration data relative to the running daemon. If the modules are loaded and
executed by the master, then the master configuration data is available, if the
modules are executed by the minion, then the minion configuration is
available. Any additional information passed into the respective configuration
files is made available
Defined in: Auth, Beacons, Engines, Execution, Executors, Outputters, Pillars, Proxies, Renderers, Returners, Runners, SDB, SSH Wrappers, State, Thorium
__salt__ contains the execution module functions. This allows for all
functions to be called as they have been set up by the salt loader.
When used in runners or outputters,
__salt__ references other
runner/outputter modules, and not execution modules.
Filled in for: Execution, Pillar, Renderer, Returner, SSH Wrapper, State.
__grains__ dictionary contains the grains data generated by the minion
that is currently being worked with. In execution modules, state modules and
returners this is the grains of the minion running the calls, when generating
the external pillar the
__grains__ is the grains data from the minion that
the pillar is being generated for.
__grains__ is defined for every module, it's only filled in for some.
Filled in for: Execution, Renderer, Returner, SSH Wrapper, State
__pillar__ dictionary contains the pillar for the respective minion.
__pillar__ is defined for every module, it's only filled in for some.
Filled in for: Pillar
__ext_pillar__ dictionary contains the external pillar modules.
During a state run the
__context__ dictionary persists across all states
that are run and then is destroyed when the state ends.
A great place to see how to use
__context__ is in the cp.py module in
salt/modules/cp.py. The fileclient authenticates with the master when it is
instantiated and then is used to copy files to the minion. Rather than create a
new fileclient for each file that is to be copied down, one instance of the
fileclient is instantiated in the
__context__ dictionary and is reused for
each file. Here is an example from salt/modules/cp.py:
if not 'cp.fileclient' in __context__:
__context__['cp.fileclient'] = salt.fileclient.get_file_client(__opts__)
Because __context__ may or may not have been destroyed, always be sure to check for the existence of the key in __context__ and generate the key before using it.
Defined in: Cloud, Engine, Execution, File Server, Grain, Pillar, Proxy, Roster, Runner, SDB, State
Defined in: Beacon, Engine, Execution, Executor, Proxy, Renderer, Returner, State, Util
Defined in: Engine, Roster, Thorium
When used in engines, it should be called __runners__ (plural)
Defined in: Executor
Defined in: Proxy
Defined in: Thorium
Defined in: Renderers, State
Defined in: State
Defined in: SDB