Schedulers are responsible for initiating builds on builders.

Some schedulers listen for changes from ChangeSources and generate build sets
in response to these changes.  Others generate build sets without changes,
based on other events in the buildmaster.

@menu
* Configuring Schedulers::
* Change Filters::
* SingleBranchScheduler::
* AnyBranchScheduler::
* Dependent Scheduler::
* Periodic Scheduler::
* Nightly Scheduler::
* Try Schedulers::
* Triggerable Scheduler::
* Scheduler Index::
@end menu

@node Configuring Schedulers
@subsection Configuring Schedulers

@bcindex c['schedulers']
@code{c['schedulers']} is a list of Scheduler instances, each
of which causes builds to be started on a particular set of
Builders. The two basic Scheduler classes you are likely to start
with are @code{Scheduler} and @code{Periodic}, but you can write a
customized subclass to implement more complicated build scheduling.

Scheduler arguments should always be specified by name (as keyword arguments),
to allow for future expansion:

@example
sched = Scheduler(name="quick", builderNames=['lin', 'win'])
@end example

There are several common arguments for schedulers, although not all are
available with all schedulers.

@table @code
@item name

Each Scheduler must have a unique name. This is used in status
displays, and is also available in the build property @code{scheduler}.

@item builderNames

This is the set of builders which this scheduler should trigger, specified
as a list of names (strings).

@item properties
@cindex Properties

This is a dictionary specifying properties that will be transmitted to all
builds started by this scheduler.  The @code{owner} property may be of
particular interest, as its contents (as a list) will be added to the list of
"interested users" (@pxref{Doing Things With Users}) for each triggered build.
For example:

@example
sched = Scheduler(...,
    properties = @{ 'owner' : [ 'zorro@@company.com', 'silver@@company.com' ] @})
@end example

@item fileIsImportant
A callable which takes one argument, a Change instance, and returns
@code{True} if the change is worth building, and @code{False} if
it is not.  Unimportant Changes are accumulated until the build is
triggered by an important change.  The default value of None means
that all Changes are important.

@item change_filter
The change filter that will determine whch changes are recognized by this
scheduler; @pxref{Change Filters}.  Note that this is different from
@code{fileIsImportant}: if the change filter filters out a Change, then it is
completely ignored by the scheduler.  If a Change is allowed by the change
filter, but is deemed unimportant, then it will not cause builds to start, but
will be remembered and shown in status displays.

@end table

The remaining subsections represent a catalog of the available Scheduler types.
All these Schedulers are defined in modules under @code{buildbot.schedulers},
and the docstrings there are the best source of documentation on the arguments
taken by each one.

@node Change Filters
@subsection Change Filters
@slindex buildbot.schedulers.filter.ChangeFilter

Several schedulers perform filtering on an incoming set of changes.  The filter
can most generically be specified as a ChangeFilter.  Set up a ChangeFilter
like this:

@example
from buildbot.changes.filter import ChangeFilter
my_filter = ChangeFilter(
    project_re="^baseproduct/.*",
    branch="devel")
@end example

and then add it to a scheduler with the @code{change_filter} parameter:

@example
sch = SomeSchedulerClass(...,
    change_filter=my_filter)
@end example

There are four attributes of changes on which you can filter:

@itemize
@item @code{project}
the project string, as defined by the ChangeSource.
@item @code{repository}
the repository in which this change occurred.
@item @code{branch}
the branch on which this change occurred.  Note that 'trunk' or 'master' is often
denoted by @code{None}.
@item @code{category}
the category, again as defined by the ChangeSource.
@end itemize

For each attribute, the filter can look for a single, specific value:
@example
my_filter = ChangeFilter(project = 'myproject')
@end example

or accept any of a set of values:

@example
my_filter = ChangeFilter(project = ['myproject', 'jimsproject'])
@end example

It can apply a regular expression, use the attribute name with a suffix of
@code{_re}:

@example
my_filter = ChangeFilter(category_re = '.*deve.*')
# or, to use regular expression flags:
import re
my_filter = ChangeFilter(category_re = re.compile('.*deve.*', re.I))
@end example

For anything more complicated, define a Python function to recognize the strings
you want:

@example
def my_branch_fn(branch):
    return branch in branches_to_build and branch not in branches_to_ignore
my_filter = ChangeFilter(branch_fn = my_branch_fn)
@end example

The special argument @code{filter_fn} can be used to specify a function that is
given the entire Change object, and returns a boolean.

A Change passes the filter only if @i{all} arguments are satisfied.  If no
filter object is given to a scheduler, then all changes will be built (subject
to any other restrictions the scheduler enforces).

@node SingleBranchScheduler
@subsection SingleBranchScheduler
@slindex buildbot.schedulers.basic.SingleBranchScheduler

This is the original and still most popular scheduler class. It follows
exactly one branch, and starts a configurable tree-stable-timer after
each change on that branch. When the timer expires, it starts a build
on some set of Builders. The scheduler accepts a @code{fileIsImportant}
function which can be used to ignore some Changes if they do not
affect any ``important'' files.

The arguments to this scheduler are:

@table @code
@item name

@item builderNames

@item properties

@item fileIsImportant

@item change_filter
@pxref{Configuring Schedulers}

@item treeStableTimer
The scheduler will wait for this many seconds before starting the
build. If new changes are made during this interval, the timer will be
restarted, so really the build will be started after a change and then
after this many seconds of inactivity.

If treeStableTimer is @code{None}, then a separate build is started
immediately for each Change.

@item categories (deprecated; use change_filter)
A list of categories of changes that this scheduler will respond to.  If this
is specified, then any non-matching changes are ignored.

@item branch (deprecated; use change_filter)
The scheduler will pay attention to this branch, ignoring Changes that occur
on other branches. Setting @code{branch} equal to the special value of
@code{None} means it should only pay attention to the default branch. Note that
@code{None} is a keyword, not a string, so write @code{None} and not
@code{"None"}.

@end table

Example:

@example
from buildbot.schedulers.basic  import SingleBranchScheduler
quick = SingleBranchScheduler(name="quick",
                    branch=None,
                    treeStableTimer=60,
                    builderNames=["quick-linux", "quick-netbsd"])
full = SingleBranchScheduler(name="full",
                    branch=None,
                    treeStableTimer=5*60,
                    builderNames=["full-linux", "full-netbsd", "full-OSX"])
c['schedulers'] = [quick, full]
@end example

In this example, the two ``quick'' builders are triggered 60 seconds
after the tree has been changed. The ``full'' builds do not run quite
so quickly (they wait 5 minutes), so hopefully if the quick builds
fail due to a missing file or really simple typo, the developer can
discover and fix the problem before the full builds are started. Both
Schedulers only pay attention to the default branch: any changes
on other branches are ignored by these schedulers. Each scheduler
triggers a different set of Builders, referenced by name.

@slindex buildbot.schedulers.basic.Scheduler
@slindex buildbot.scheduler.Scheduler
The old names for this scheduler, @code{buildbot.scheduler.Scheduler} and
@code{buildbot.schedulers.basic.Scheduler}, are deprecated in favor of the more
accurate name @code{SingleBranchScheduler}.

@node AnyBranchScheduler
@subsection AnyBranchScheduler
@slindex buildbot.schedulers.basic.AnyBranchScheduler

This scheduler uses a tree-stable-timer like the default one, but
uses a separate timer for each branch.

The arguments to this scheduler are:

@table @code
@item name

@item builderNames

@item properties

@item fileIsImportant

@item change_filter
@pxref{Configuring Schedulers}

@item treeStableTimer
The scheduler will wait for this many seconds before starting the
build. If new changes are made during this interval, the timer will be
restarted, so really the build will be started after a change and then
after this many seconds of inactivity.

@item branches (deprecated; use change_filter)
This scheduler will pay attention to any number of branches, ignoring
Changes that occur on other branches. 

@item categories (deprecated; use change_filter)
A list of categories of changes that this scheduler will respond to.  If this
is specified, then any non-matching changes are ignored.

@end table

@node Dependent Scheduler
@subsection Dependent Scheduler
@cindex Dependent
@cindex Dependencies
@slindex buildbot.schedulers.dependent.Dependent
@slindex buildbot.schedulers.basic.Dependent

It is common to wind up with one kind of build which should only be
performed if the same source code was successfully handled by some
other kind of build first. An example might be a packaging step: you
might only want to produce .deb or RPM packages from a tree that was
known to compile successfully and pass all unit tests. You could put
the packaging step in the same Build as the compile and testing steps,
but there might be other reasons to not do this (in particular you
might have several Builders worth of compiles/tests, but only wish to
do the packaging once). Another example is if you want to skip the
``full'' builds after a failing ``quick'' build of the same source
code. Or, if one Build creates a product (like a compiled library)
that is used by some other Builder, you'd want to make sure the
consuming Build is run @emph{after} the producing one.

You can use ``Dependencies'' to express this relationship
to the Buildbot. There is a special kind of scheduler named
@code{scheduler.Dependent} that will watch an ``upstream'' scheduler
for builds to complete successfully (on all of its Builders). Each time
that happens, the same source code (i.e. the same @code{SourceStamp})
will be used to start a new set of builds, on a different set of
Builders. This ``downstream'' scheduler doesn't pay attention to
Changes at all. It only pays attention to the upstream scheduler.

If the build fails on any of the Builders in the upstream set,
the downstream builds will not fire.  Note that, for SourceStamps
generated by a ChangeSource, the @code{revision} is None, meaning HEAD.
If any changes are committed between the time the upstream scheduler
begins its build and the time the dependent scheduler begins its
build, then those changes will be included in the downstream build.
See the @pxref{Triggerable Scheduler} for a more flexible dependency
mechanism that can avoid this problem.

The keyword arguments to this scheduler are:

@table @code
@item name

@item builderNames

@item properties

@item upstream
The upstream scheduler to watch.  Note that this is an ``instance'',
not the name of the scheduler.
@end table

Example:

@example
from buildbot.schedulers import dependent
tests = basic.SingleBranchScheduler(name="just-tests", branch=None,
                treeStableTimer=5*60,
                builderNames=["full-linux", "full-netbsd", "full-OSX"])
package = dependent.Dependent(name="build-package",
                upstream=tests, # <- no quotes!
                builderNames=["make-tarball", "make-deb", "make-rpm"])
c['schedulers'] = [tests, package]
@end example

@node Periodic Scheduler
@subsection Periodic Scheduler
@slindex buildbot.schedulers.timed.Periodic

This simple scheduler just triggers a build every N seconds.

The arguments to this scheduler are:

@table @code
@item name

@item builderNames

@item properties

@item periodicBuildTimer
The time, in seconds, after which to start a build.
@end table

Example:

@example
from buildbot.schedulers import timed
nightly = timed.Periodic(name="daily",
                builderNames=["full-solaris"],
                periodicBuildTimer=24*60*60)
c['schedulers'] = [nightly]
@end example

The scheduler in this example just runs the full solaris build once per day.
Note that this scheduler only lets you control the time between builds, not the
absolute time-of-day of each Build, so this could easily wind up an ``evening''
or ``every afternoon'' scheduler depending upon when it was first activated.

@node Nightly Scheduler
@subsection Nightly Scheduler
@slindex buildbot.schedulers.timed.Nightly

This is highly configurable periodic build scheduler, which triggers
a build at particular times of day, week, month, or year. The
configuration syntax is very similar to the well-known @code{crontab}
format, in which you provide values for minute, hour, day, and month
(some of which can be wildcards), and a build is triggered whenever
the current time matches the given constraints. This can run a build
every night, every morning, every weekend, alternate Thursdays,
on your boss's birthday, etc.

Pass some subset of @code{minute}, @code{hour}, @code{dayOfMonth},
@code{month}, and @code{dayOfWeek}; each may be a single number or
a list of valid values. The builds will be triggered whenever the
current time matches these values. Wildcards are represented by a
'*' string. All fields default to a wildcard except 'minute', so
with no fields this defaults to a build every hour, on the hour.
The full list of parameters is:

@table @code
@item name

@item builderNames

@item properties

@item fileIsImportant

@item branch
(required) The branch to build when the time comes.  Remember that a value of
@code{None} here means the default branch, and will not match other branches!

@item change_filter
@pxref{Configuring Schedulers}.  Note that @code{fileIsImportant} and
@code{change_filter} are only relevant if @code{onlyIfChanged} is true.

@item minute
The minute of the hour on which to start the build.  This defaults
to 0, meaning an hourly build.

@item hour
The hour of the day on which to start the build, in 24-hour notation.
This defaults to *, meaning every hour.

@item dayOfMonth
The day of the month to start a build.  This defauls to *, meaning every day.

@item month
The month in which to start the build, with January = 1.  This defaults
to *, meaning every month.

@item dayOfWeek
The day of the week to start a build, with Monday = 0.  This defauls to *,
meaning every day of the week.  If @code{dayOfMonth} and @code{dayOfWeek} are
both specified, builds will be started when @emph{either} parameter matches.

@item onlyIfChanged
If this is true, then builds will not be scheduled at the designated time
@emph{unless} the specified branch has seen an important change since the
previous build.

@end table

For example, the following master.cfg clause will cause a build to be
started every night at 3:00am:

@example
from buildbot.schedulers import timed
s = timed.Nightly(name='nightly',
        branch='master',
        builderNames=['builder1', 'builder2'],
        hour=3,
        minute=0)
@end example

This scheduler will perform a build each monday morning at 6:23am and
again at 8:23am, but only if someone has committed code in the interim:

@example
s = timed.Nightly(name='BeforeWork',
         branch='default',
         builderNames=['builder1'],
         dayOfWeek=0,
         hour=[6,8],
         minute=23,
         onlyIfChanged=True)
@end example

The following runs a build every two hours, using Python's @code{range}
function:

@example
s = timed.Nightly(name='every2hours',
        branch=None, # default branch
        builderNames=['builder1'],
        hour=range(0, 24, 2))
@end example

Finally, this example will run only on December 24th:

@example
s = timed.Nightly(name='SleighPreflightCheck',
        branch=None, # default branch
        builderNames=['flying_circuits', 'radar'],
        month=12,
        dayOfMonth=24,
        hour=12,
        minute=0)
@end example

@node Try Schedulers
@subsection Try Schedulers
@slindex buildbot.schedulers.trysched.Try_Jobdir
@slindex buildbot.schedulers.trysched.Try_Userpass

This scheduler allows developers to use the @code{buildbot try}
command to trigger builds of code they have not yet committed. See
@ref{try} for complete details.

Two implementations are available: @code{Try_Jobdir} and
@code{Try_Userpass}.  The former monitors a job directory, specified
by the @code{jobdir} parameter, while the latter listens for PB
connections on a specific @code{port}, and authenticates against
@code{userport}.

The buildmaster must have a scheduler instance in the config file's
@code{c['schedulers']} list to receive try requests. This lets the
administrator control who may initiate these ``trial'' builds, which branches
are eligible for trial builds, and which Builders should be used for them.

The scheduler has various means to accept build requests.
All of them enforce more security than the usual buildmaster ports do.
Any source code being built can be used to compromise the buildslave
accounts, but in general that code must be checked out from the VC
repository first, so only people with commit privileges can get
control of the buildslaves. The usual force-build control channels can
waste buildslave time but do not allow arbitrary commands to be
executed by people who don't have those commit privileges. However,
the source code patch that is provided with the trial build does not
have to go through the VC system first, so it is important to make
sure these builds cannot be abused by a non-committer to acquire as
much control over the buildslaves as a committer has. Ideally, only
developers who have commit access to the VC repository would be able
to start trial builds, but unfortunately the buildmaster does not, in
general, have access to VC system's user list.

As a result, the try scheduler requires a bit more configuration. There are
currently two ways to set this up:

@table @strong
@item jobdir (ssh)

This approach creates a command queue directory, called the
``jobdir'', in the buildmaster's working directory. The buildmaster
admin sets the ownership and permissions of this directory to only
grant write access to the desired set of developers, all of whom must
have accounts on the machine. The @code{buildbot try} command creates
a special file containing the source stamp information and drops it in
the jobdir, just like a standard maildir. When the buildmaster notices
the new file, it unpacks the information inside and starts the builds.

The config file entries used by 'buildbot try' either specify a local
queuedir (for which write and mv are used) or a remote one (using scp
and ssh).

The advantage of this scheme is that it is quite secure, the
disadvantage is that it requires fiddling outside the buildmaster
config (to set the permissions on the jobdir correctly). If the
buildmaster machine happens to also house the VC repository, then it
can be fairly easy to keep the VC userlist in sync with the
trial-build userlist. If they are on different machines, this will be
much more of a hassle. It may also involve granting developer accounts
on a machine that would not otherwise require them.

To implement this, the buildslave invokes 'ssh -l username host
buildbot tryserver ARGS', passing the patch contents over stdin. The
arguments must include the inlet directory and the revision
information.

@item user+password (PB)

In this approach, each developer gets a username/password pair, which
are all listed in the buildmaster's configuration file. When the
developer runs @code{buildbot try}, their machine connects to the
buildmaster via PB and authenticates themselves using that username
and password, then sends a PB command to start the trial build.

The advantage of this scheme is that the entire configuration is
performed inside the buildmaster's config file. The disadvantages are
that it is less secure (while the ``cred'' authentication system does
not expose the password in plaintext over the wire, it does not offer
most of the other security properties that SSH does). In addition, the
buildmaster admin is responsible for maintaining the username/password
list, adding and deleting entries as developers come and go.

@end table

For example, to set up the ``jobdir'' style of trial build, using a
command queue directory of @file{MASTERDIR/jobdir} (and assuming that
all your project developers were members of the @code{developers} unix
group), you would first set up that directory:

@example
mkdir -p MASTERDIR/jobdir MASTERDIR/jobdir/new MASTERDIR/jobdir/cur MASTERDIR/jobdir/tmp
chgrp developers MASTERDIR/jobdir MASTERDIR/jobdir/*
chmod g+rwx,o-rwx MASTERDIR/jobdir MASTERDIR/jobdir/*
@end example

and then use the following scheduler in the buildmaster's config file:

@example
from buildbot.schedulers.trysched import Try_Jobdir
s = Try_Jobdir(name="try1",
               builderNames=["full-linux", "full-netbsd", "full-OSX"],
               jobdir="jobdir")
c['schedulers'] = [s]
@end example

Note that you must create the jobdir before telling the buildmaster to
use this configuration, otherwise you will get an error. Also remember
that the buildmaster must be able to read and write to the jobdir as
well. Be sure to watch the @file{twistd.log} file (@pxref{Logfiles})
as you start using the jobdir, to make sure the buildmaster is happy
with it.

To use the username/password form of authentication, create a
@code{Try_Userpass} instance instead. It takes the same
@code{builderNames} argument as the @code{Try_Jobdir} form, but
accepts an addtional @code{port} argument (to specify the TCP port to
listen on) and a @code{userpass} list of username/password pairs to
accept. Remember to use good passwords for this: the security of the
buildslave accounts depends upon it:

@example
from buildbot.schedulers.trysched import Try_Userpass
s = Try_Userpass(name="try2",
                 builderNames=["full-linux", "full-netbsd", "full-OSX"],
                 port=8031,
                 userpass=[("alice","pw1"), ("bob", "pw2")] )
c['schedulers'] = [s]
@end example

Like most places in the buildbot, the @code{port} argument takes a
strports specification. See @code{twisted.application.strports} for
details.

@node Triggerable Scheduler
@subsection Triggerable Scheduler
@cindex Triggers
@slindex buildbot.schedulers.triggerable.Triggerable

The @code{Triggerable} scheduler waits to be triggered by a Trigger
step (see @ref{Triggering Schedulers}) in another build. That step
can optionally wait for the scheduler's builds to complete. This
provides two advantages over Dependent schedulers. First, the same
scheduler can be triggered from multiple builds. Second, the ability
to wait for a Triggerable's builds to complete provides a form of
"subroutine call", where one or more builds can "call" a scheduler
to perform some work for them, perhaps on other buildslaves.

The parameters are just the basics:

@table @code
@item name
@item builderNames
@item properties
@end table

This class is only useful in conjunction with the @code{Trigger} step.
Here is a fully-worked example:

@example
from buildbot.schedulers import basic, timed, triggerable
from buildbot.process import factory
from buildbot.steps import trigger

checkin = basic.SingleBranchScheduler(name="checkin",
            branch=None,
            treeStableTimer=5*60,
            builderNames=["checkin"])
nightly = timed.Nightly(name='nightly',
            builderNames=['nightly'],
            hour=3,
            minute=0)

mktarball = triggerable.Triggerable(name="mktarball",
                builderNames=["mktarball"])
build = triggerable.Triggerable(name="build-all-platforms",
                builderNames=["build-all-platforms"])
test = triggerable.Triggerable(name="distributed-test",
                builderNames=["distributed-test"])
package = triggerable.Triggerable(name="package-all-platforms",
                builderNames=["package-all-platforms"])

c['schedulers'] = [mktarball, checkin, nightly, build, test, package]

# on checkin, make a tarball, build it, and test it
checkin_factory = factory.BuildFactory()
checkin_factory.addStep(trigger.Trigger(schedulerNames=['mktarball'],
                                       waitForFinish=True))
checkin_factory.addStep(trigger.Trigger(schedulerNames=['build-all-platforms'],
                                   waitForFinish=True))
checkin_factory.addStep(trigger.Trigger(schedulerNames=['distributed-test'],
                                  waitForFinish=True))

# and every night, make a tarball, build it, and package it
nightly_factory = factory.BuildFactory()
nightly_factory.addStep(trigger.Trigger(schedulerNames=['mktarball'],
                                       waitForFinish=True))
nightly_factory.addStep(trigger.Trigger(schedulerNames=['build-all-platforms'],
                                   waitForFinish=True))
nightly_factory.addStep(trigger.Trigger(schedulerNames=['package-all-platforms'],
                                     waitForFinish=True))
@end example

@node Scheduler Index
@subsection Scheduler Index
@printindex sl
