Introduction¶

Spicerack - Automation framework for the WMF production infrastructure¶

Spicerack provides an entry point to all the libraries needed to automate and orchestrate tasks inside the Wikimedia Foundation's (WMF) production infrastructure. It provides also an entry point script cookbook to list and run the available cookbooks, both one by one or via an interactive menu.

Cookbooks API¶

Collection of cookbooks to automate and orchestrate operations in the WMF infrastructure. The cookbooks will be executed by the cookbook entry point script of the spicerack package.

Cookbooks hierarchy¶

The cookbooks must be structured in a tree, as they can be run also from an interactive menu that shows the tree from an arbitrary entry point downwards.

Each cookbook filename must be a valid Python module name, hence all lowercase, with underscore if that improves readability and that doesn't start with a number.

Given that the cookbooks are imported dynamically, a broader set of characters like dashes and starting with a number are technically allowed and the current standard at WMF is to name the cookbooks with dashes instead of underscores.

Example of cookbooks tree:

cookbooks
|-- __init__.py
|-- top-level-cookbook.py
|-- group1
|   |-- __init__.py
|   `-- important-cookbook.py
`-- group2
    |-- __init__.py
    `-- subgroup1
        |-- __init__.py
        `-- some-task.py

API interfaces¶

Each cookbook must follow one of the two available API interfaces:

Class interface (preferred)
Module interface

Class interface¶

A more integrated class-based API interface. Each cookbook must define two classes that extends spicerack.cookbook.CookbookBase and spicerack.cookbook.CookbookRunnerBase respectively, defining the required abstract methods and optionally overriding the default implementation of the concrete ones.

The Spicerack framework will instantiate the class derived from CookbookBase passing to it an initialized spicerack.Spicerack instance. Then it will call its argument_parser method to get the argparse instance and with that parse the CLI arguments. After that it will call the get_runner method that must return an instance of a class derived from CookbookRunnerBase. The runtime_description property will be used to customize the default START/STOP IRC messages. Up to this point any exception raised will be considered a pre-failure and make the cookbook fail before IRC-logging its start.

Then the run method will be called to actually run the cookbook.

If the run method returns a non-zero exit code or raises any exception the optional rollback method will be called to allow the cookbook to perform any cleanup action. Any exception raised by the rollback method will be logged and the cookbook will exit with a reserved exit code.

The derived classes can have any name and multiple cookbooks in the same module are supported.

Module interface¶

A simple function-based API interface for the cookbooks in which each cookbook is a Python module that defines the following constants and functions.

cookbook-module.__title__¶

A module attribute that defines the cookbook title. It must be a single line string.

Type: str

cookbook-module.argument_parser() → argparse.ArgumentParser:¶

Optional module function to define if the cookbook should accept command line arguments.

If defined the returned argument parser will be used to parse the cookbook's arguments.

If not defined it means that the cookbook doesn't accept any argument and if called with arguments it's considered an error.

Cookbooks are encouraged to define an argument_parser() function so that an help message is automatically available with -h/--help and it can be shown both when running a cookbook directly or in the interactive menu.

Returns: the argument parser instance.
Return type: argparse.ArgumentParser

cookbook-module.run(args, spicerack)¶

Mandatory module function with the actual execution of the cookbook.

Parameters

args (argparse.Namespace or None) -- the parsed arguments that were parsed using the defined argument_parser() module function or None if the cookbook doesn't support any argument.
spicerack (spicerack.Spicerack) -- the Spicerack accessor instance with which the cookbook can access all the Spicerack capabilities.

Returns

the return code of the cookbook, it should be zero or None on success, a positive integer smaller than 128 and not in the range 90-99 (see Reserved exit codes) in case of failure.

Return type

int or None

Logging¶

The logging is already pre-setup by the cookbook entry point script that initialize the root logger, so that each cookbook can just initialize its own logging instance and log.

A special logger to send notification to the #wikimedia-operations IRC channel with the !log prefix is also available through the spicerack argument, passed to the cookbook's run() function for the module API or available in the cookbook class as self.spicerack for the class API, in its irc_logger property.

The irc_logger logs to both IRC and the nomal log outputs of Spicerack. If the dry-run mode is set it does not log to IRC.

Log files¶

The log files can be found in /var/log/spicerack/${PATH_OF_THE_COOKBOOK} on the host where the cookbooks are run. All normal log messages are sent to two separate files, of which one always logs at DEBUG level even if -v/--verbose is not set. So for example running the cookbook foo.bar.baz will generate two log files:

/var/log/spicerack/foo/bar/baz.log  # with INFO and higher log levels
/var/log/spicerack/foo/bar/baz-extended.log  # with all log levels

If the cookbook is started with a directory of multiple cookbooks then the logs are all concentrated in the directory path ones:

/var/log/spicerack/foo/bar.log  # with INFO and higher log levels
/var/log/spicerack/foo/bar-extended.log  # with all log levels

Example¶

import logging

 logger = logging.getLogger(__name__)

 logger.info('message')  # this goes to stdout in the operator shell and is logged in both files.
 logger.debug('message') # this goes to stdout in the operator shell only if -v/--verbose is set and is logged only
                         # in the extended file.

 def run(args, spicerack):
     spicerack.irc_logger.info('message')  # This sends a message to the #wikimedia-operation IRC channel with:
                                           # !log user@host message

Spicerack library¶

All the available modules in the Spicerack package are exposed to the cookbooks through the spicerack instance injected in the cookbook. It offers helper methods to obtain initialized instances of all the available libraries. This instance exposes also some of the global CLI arguments parsed by the cookbook entry point script such as dry_run and verbose as getters. See spicerack.Spicerack for more details.

Exception handling¶

In general each module in the spicerack package has its own exception class to raise specific errors, and all of them are derived from the base class spicerack.exceptions.SpicerackError.

Reserved exit codes¶

Cookbook exit codes in the range 90-99 are reserved by Spicerack and must not be used by the cookbooks. The currently defined reserved exit codes are documented in the spicerack.cookbook module.