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README.rst

Async interface to Koji, using Twisted

Access Koji's XML-RPC API asynchronously (non-blocking) using the Twisted framework.

This supports the GSSAPI or Client SSL login methods.

Simple Example: Fetching a user's name

from txkoji import Connection
from twisted.internet import defer
from twisted.internet.task import react


@defer.inlineCallbacks
def example(reactor):
    koji = Connection('brew')
    # Fetch a user.
    # You may pass an ID or a krb principal here
    user = yield koji.getUser(3595)
    # user is a Munch (dict-like) object.
    print(user.name)


if __name__ == '__main__':
    react(example)

Connecting to a Koji Hub

To connect to a Koji hub, create a new txkoji.Connection instance.

You must pass a string to the constructor. This string is a profile name. For example, if you call Connector('mykoji'), then txkoji will search ~/.koji/config.d/*.conf and /etc/koji.conf.d/*.conf for the [mykoji] config section. This matches what the regular Koji client code does.

Making XML-RPC calls

Koji Hub is an XML-RPC server. You can call any method on the Connection class instance and txkoji will treat it as an XML-RPC call to the hub. For example, this Twisted inlineCallbacks-style code looks up information about a given task ID and tag ID:

@defer.inlineCallbacks
def example(reactor):
    koji = Connection('mykoji')

    task = yield koji.getTaskInfo(10000)
    print(task.method)  # "createImage"

    tag = yield koji.getTag(2000)
    print(tag.name)  # "foo-build"

To learn the full Koji XML-RPC API:

koji list-api

You can also read the koji source code to find out details about how each method works.

Logging in

Your Koji hub must support GSSAPI or Client SSL authentication. You must have a valid Kerberos ticket or SSL keypair.

@defer.inlineCallbacks
def example(reactor):
    koji = Connection('mykoji')

    result = yield login()
    print(result)  # "True"
    print('session-id: %s' % koji.session_id)

    # "Who am I?"
    user = yield koji.getLoggedInUser()
    print(user)

Estimating build durations

The txkoji.estimates module provides methods for estimating build times. The average_build_duration() method calls Koji's getAverageBuildDuration RPC and gives you a datetime.timedelta for a package. For container packages, we do something similar client-side with the average_last_builds() method, averaging the last five builds' durations.

Caching long-lived object names

Sometimes all you have is a user id number or tag id number, and you want the user's name or tag's name instead.

txkoji includes a read-through cache for obtaining the user name or tag name. See examples/cache.py for an example. txkoji's cache module stores its data in a txkoji subdirectory of the location specified with the $XDG_CACHE_HOME environment variable if that is set. It will fall back to using ~/.cache/txkoji if the $XDG_CACHE_HOME environment variable is not set.

Rich objects

The following RPC methods will return special classes that inherit from the Munch class:

  • getBuild returns txkoji.build.Build
  • getChannel returns txkoji.channel.Channel
  • listBuilds and listTagged returns a list of txkoji.build.Build
  • getTaskInfo returns txkoji.task.Task
  • getPackage returns txkoji.package.Package

These classes have their own special helper methods to implement things I found interesting:

  • datetime conversions for the start/completion timestamps,
  • url properties for representing the objects in Kojiweb,
  • Unified property attributes across task methods, like tag, package or is_scratch.

More special return values:

  • getAverageBuildDuration returns a datetime.timedelta object instead of a raw float, because this is more useful to do time arithmetic.
  • The task_id property is populated on OSBS's CG container builds (a workaround for https://pagure.io/koji/issue/215).

Multi-call support

If you have to submit many RPCs to koji-hub at once, you can optimize this with "multicall".

Koji's XML-RPC implementation allows you to batch or "boxcar" many methods up into one single "multicall" RPC and send it to the server as one single HTTP request.

@defer.inlineCallbacks
def example(reactor):
    koji = Connection('mykoji')

    multicall = koji.MultiCall()
    # Query the task information for several tasks in one shot:
    multicall.getTaskInfo(123)
    multicall.getTaskInfo(456)
    multicall.getTaskInfo(789)
    results = yield multicall()
    # results is a xmlrpc.client.MultiCallIterator
    for task in iter(results):
        print(task.id)  # eg. "123" or "456" or "789"
        print(task.method)  # eg. "tagBuild"

This is a bit similar to Twisted's DeferredList / gatherResults, although it happens server-side instead of purely client-side.

If the hub returns an error for any of the calls within the multicall, the iterator will raise KojiException when iterating over the specific call result that had the error.

Message Parsing

Koji's messagebus plugin emits messages to an AMQP broker when certain events happen. The txkoji.messages module has support for parsing these messages into the relevant txkoji Task or Build classes.

TODO:

  • More KojiException subclasses for other possible XML-RPC faults?
  • Implement krbV authentication (probably not unless there is an alternative to python-krbV).
  • MikeM noted, the callnum parameter will need special handling. We might need Twisted's DeferredLock to ensure we only have one auth'd RPC in flight at a time. It's not really clear to me if we can actually hit a callnum error here. More integration testing needed for this.
  • Ensure that Brew's "build time" equals the longest "buildArch" time for a task, and not something else, like the buildSRPMFromSCM time, nor even the overall build task's time. This has implications for estimating scratch builds. (comparing our tasks' times to getAverageBuildDuration)

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