Tracer API

Tracer provides a small interface that you can use in your application. It consist from Query class which is able to ask Tracer for various informations and provide you a results. And from data structues from which results consists.

Surely you could access internal classes and methods on your own, but there is a risk that they will change in the future. In API could be a little changes too, but they will be documented

Quering

class tracer.Query(tracer=<class 'tracer.resources.tracer.Tracer'>)[source]

Provide API for Tracer quering operations. They are executed kind of lazily, so running the operation will return just an wrapper class with get() method.

Example:

from tracer.query import Query
q = Query()
q.affected_applications().get()

Note

Some quering methods can require root permissions

affected_applications(user=None)[source]

Return list of applications which use some outdated files

from_packages(packages)[source]

List of Package that only should be traced

now()[source]

Pretend that specified packages have been updated just now. Benefit of this is absolutely no need for openning the package history database

Hooks

Tracer also provides API for user-defined hooks. They can be defined as a simple functions decorated by @hooks.match("app_name"). Tracer will search for them in directories ~/.config/tracer/hooks/ and /etc/tracer/hooks/. Such hook will be called when tracer determines, that linked application needs restarting.

tracer.hooks.match(apps)[source]

Decorator for tracer hooks.

Example:

from tracer import hooks

@hooks.match("foo")
def hook_app():
    print("Hey, application foo was found")

Note

You can match multiple applications by calling @hooks.match with list of them.

Note

If you want to run tracer’s hooks and print no other output, use tracer --hooks-only

Exit codes

In some use-cases you may want to examine Tracer’s results through exit codes (also known as status codes). See their meanings:

1-99 Error exit codes
0 No affected applications
101 Found some affected applications
102 Found some affected daemons
103 Session restart needed
104 Reboot needed

Data structures

Follows list of classes which quering results may consist from. Not all their properties are covered within API. If your use case requires some which are not listed below, please let me know to cover them in API too.

Packages

class tracer.Package(name, modified=None)[source]

Represents linux package

modified = None

UNIX timestamp of the modification

name = None

Name of the package

Applications

class tracer.Application(attributes_dict)[source]

Represent the application defined in applications.xml

Parameters:
  • name (str) – The name of the application
  • type (str) – See Applications.TYPES for possible values
  • helper (str) – Describes how to restart the applications
  • note (bool) – Provides additional informations to the helper
  • ignore (bool) – If True, the application won’t be printed
  • processes_factory (Processes) – Class providing list of running processes
helpers

Return the list of helpers which describes how to restart the application. When no helper_format was described, empty list will be returned. If helper_format contains process specific arguments such a {PID}, etc. list will contain helper for every application instance. In other cases, there will be just one helper in the list.

instances

Return collection of processes with same name as application. I.e. running instances of the application

class tracer.Process(pid=None)[source]

Represent the process instance uniquely identifiable through PID

For all class properties and methods, please see http://pythonhosted.org/psutil/#process-class

Bellow listed are only reimplemented ones.

children(recursive=False)[source]

The collection of process’s children. Each of them casted from psutil.Process to tracer Process.

exe

The absolute path to process executable. Cleaned from arbitrary strings which appears on the end.

parent()[source]

The parent process casted from psutil.Process to tracer Process

username()[source]

The user who owns the process. If user was deleted in the meantime, None is returned instead.