SiteExtensions

Adding site-specific extensions

If you need to extend the Autotest code in a way that isn't usable by the main project, then you'll probably want to do so in a way that doesn't unduly complicate merging your local, extended code with the official project code. In general this means that you want to pull any site-specific code into separate files, and have the main code call into the extension in an optional way.

For site-specific tests this is not a problem. Each test should be self-contained in its own directory and so you should be able to add new tests without any other changes to Autotest at all. There may occasionally be a conflict if a new test is added to the project that conflicts with a private name you're already using, but this will should not be overly common and is easily fixed by renaming.

For adding site-specific common libraries, this is also not a big problem. Add your module to the client/common_lib directory but add the name of your module to client/common_lib/site_libraries.py instead of directly to client/common_lib/__init__.py. This will create a small conflict as your local client/common_lib/site_libraries.py will differ from the official one, however since the official one should never really be changing, merging should never be a problem. However, remember that any code that imports these site-specific libraries has itself become site-specific.

In any other cases where you have to modify the core Autotest code, you'll have to make an effort to separate out your extensions from the main body of code. Assuming your extension is being done in a file x.py, the easiest way to extend it is to add a new module site_x.py that contains your site specific-code, and then add code to x.py that imports site_x and makes the appropriate calls.

Now, you'll want to be able to push out these calls to site_x into the official code so that you don't have to constantly merge around them. That means you'll still have to be careful about how you use site_x. In particular:

1. the import of site_x has to be done in such a way the code still works properly when site_x doesn't exist
2. the coupling between x and site_x should be as minimal as possible (to reduce the chances that other people's changes to x inadvertently break site_x)

As an example, look at the use of site_kernel in client/bin/kernel.py. It supports point 1 by pulling in a function from site_kernel, and if the import of site_kernel fails, it provides a default implementation of the function it is trying to import. It supports point 2 by only inserting a single call into auto_kernel stage, one with very clear and simple semantics (i.e. perform some optional, site-specific munging of path names before using them).

Adding site-specific extensions to the CLI

If you need to change the default behavior of some autotest-rpc-client commands, you can create a cli/site_<topic>.py file to subclass some of the classes from cli/<topic>.py.

The following example would prevent the creation of platform labels:

import inspect, new, sys

from autotest_lib.cli import topic_common, label


class site_label(label.label):
    pass


class site_label_create(label.label_create):
    """Disable the platform option
    autotest-rpc-client label create <labels>|--blist <file>"""
    def __init__(self):
        super(site_label_create, self).__init__()
        self.parser.remove_option("--platform")


    def parse(self):
        (options, leftover) = super(site_label_create, self).parse()
        self.is_platform = False
        return (options, leftover)


# The following boiler plate code should be added at the end to create
# all the other site_<topic>_<action> classes that do not modify their
# <topic>_<action> super class.

# Any classes we don't override in label should be copied automatically
for cls in [getattr(label, n) for n in dir(label) if not n.startswith("_")]:
    if not inspect.isclass(cls):
        continue
    cls_name = cls.__name__
    site_cls_name = 'site_' + cls_name
    if hasattr(sys.modules[__name__], site_cls_name):
        continue
    bases = (site_label, cls)
    members = {'__doc__': cls.__doc__}
    site_cls = new.classobj(site_cls_name, bases, members)
    setattr(sys.modules[__name__], site_cls_name, site_cls)