Customization¶
For advanced users, Buildbot acts as a framework supporting a customized build application. For the most part, such configurations consist of subclasses set up for use in a regular Buildbot configuration file.
This chapter describes some of the more common idioms in advanced Buildbot configurations.
At the moment, this chapter is an unordered set of suggestions; if you'd like to clean it up, fork the project on github and get started!
Programmatic Configuration Generation¶
Bearing in mind that master.cfg
is a Python file, large configurations can
be shortened considerably by judicious use of Python loops. For example, the
following will generate a builder for each of a range of supported versions of
Python:
pythons = [ 'python2.4', 'python2.5', 'python2.6', 'python2.7',
'python3.2', python3.3' ]
pytest_slaves = [ "slave%s" % n for n in range(10) ]
for python in pythons:
f = BuildFactory()
f.addStep(SVN(..))
f.addStep(ShellCommand(command=[ python, 'test.py' ]))
c['builders'].append(BuilderConfig(
name="test-%s" % python,
factory=f,
slavenames=pytest_slaves))
Merge Request Functions¶
The logic Buildbot uses to decide which build request can be merged can be
customized by providing a Python function (a callable) instead of True
or
False
described in Merging Build Requests.
The callable will be invoked with three positional arguments: a
Builder
object and two BuildRequest
objects. It should return
true if the requests can be merged, and False otherwise. For example:
def mergeRequests(builder, req1, req2):
"any requests with the same branch can be merged"
return req1.branch == req2.branch
c['mergeRequests'] = mergeRequests
In many cases, the details of the SourceStamp
s and BuildRequest
s are important.
In this example, only BuildRequest
s with the same "reason" are merged; thus
developers forcing builds for different reasons will see distinct builds. Note
the use of the canBeMergedWith
method to access the source stamp
compatibility algorithm.
def mergeRequests(builder, req1, req2):
if req1.source.canBeMergedWith(req2.source) and req1.reason == req2.reason:
return True
return False
c['mergeRequests'] = mergeRequests
If it's necessary to perform some extended operation to determine whether two
requests can be merged, then the mergeRequests
callable may return its
result via Deferred. Note, however, that the number of invocations of the
callable is proportional to the square of the request queue length, so a
long-running callable may cause undesirable delays when the queue length
grows. For example:
def mergeRequests(builder, req1, req2):
d = defer.gatherResults([
getMergeInfo(req1.source.revision),
getMergeInfo(req2.source.revision),
])
def process(info1, info2):
return info1 == info2
d.addCallback(process)
return d
c['mergeRequests'] = mergeRequests
Builder Priority Functions¶
The prioritizeBuilders
configuration key specifies a function which
is called with two arguments: a BuildMaster
and a list of
Builder
objects. It should return a list of the same Builder
objects, in the desired order. It may also remove items from the list if
builds should not be started on those builders. If necessary, this function can
return its results via a Deferred (it is called with maybeDeferred
).
A simple prioritizeBuilders
implementation might look like this:
def prioritizeBuilders(buildmaster, builders):
"""Prioritize builders. 'finalRelease' builds have the highest
priority, so they should be built before running tests, or
creating builds."""
builderPriorities = {
"finalRelease": 0,
"test": 1,
"build": 2,
}
builders.sort(key=lambda b: builderPriorities.get(b.name, 0))
return builders
c['prioritizeBuilders'] = prioritizeBuilders
Build Priority Functions¶
When a builder has multiple pending build requests, it uses a nextBuild
function to decide which build it should start first. This function is given
two parameters: the Builder
, and a list of BuildRequest
objects representing pending build requests.
A simple function to prioritize release builds over other builds might look like this:
def nextBuild(bldr, requests):
for r in requests:
if r.source.branch == 'release':
return r
return requests[0]
If some non-immediate result must be calculated, the nextBuild
function can
also return a Deferred:
def nextBuild(bldr, requests):
d = get_request_priorities(requests)
def pick(priorities):
if requests:
return sorted(zip(priorities, requests))[0][1]
d.addCallback(pick)
return d
Customizing SVNPoller¶
Each source file that is tracked by a Subversion repository has a
fully-qualified SVN URL in the following form:
({REPOURL})({PROJECT-plus-BRANCH})({FILEPATH})
. When you create the
SVNPoller
, you give it a svnurl
value that includes all of the
{REPOURL}
and possibly some portion of the
{PROJECT-plus-BRANCH}
string. The SVNPoller
is responsible
for producing Changes that contain a branch name and a {FILEPATH}
(which is relative to the top of a checked-out tree). The details of how these
strings are split up depend upon how your repository names its branches.
PROJECT/BRANCHNAME/FILEPATH repositories¶
One common layout is to have all the various projects that share a repository
get a single top-level directory each, with branches
, tags
, and
trunk
subdirectories:
amanda/trunk
/branches/3_2
/3_3
/tags/3_2_1
/3_2_2
/3_3_0
To set up a SVNPoller
that watches the Amanda trunk (and nothing
else), we would use the following, using the default split_file
:
from buildbot.changes.svnpoller import SVNPoller
c['change_source'] = SVNPoller(
svnurl="https://svn.amanda.sourceforge.net/svnroot/amanda/amanda/trunk")
In this case, every Change that our SVNPoller
produces will have
its branch attribute set to None
, to indicate that the Change is on the
trunk. No other sub-projects or branches will be tracked.
If we want our ChangeSource to follow multiple branches, we have to do
two things. First we have to change our svnurl=
argument to
watch more than just amanda/trunk
. We will set it to
amanda
so that we'll see both the trunk and all the branches.
Second, we have to tell SVNPoller
how to split the
({PROJECT-plus-BRANCH})({FILEPATH})
strings it gets from the repository
out into ({BRANCH})
and ({FILEPATH})`
.
We do the latter by providing a split_file
function. This function is
responsible for splitting something like branches/3_3/common-src/amanda.h
into branch='branches/3_3'
and filepath='common-src/amanda.h'
. The
function is always given a string that names a file relative to the
subdirectory pointed to by the SVNPoller
's svnurl=
argument.
It is expected to return a dictionary with at least the path
key. The
splitter may optionally set branch
, project
and repository
.
For backwards compatibility it may return a tuple of (branchname, path)
.
It may also return None
to indicate that the file is of no interest.
Note
the function should return branches/3_3
rather than just 3_3
because the SVN checkout step, will append the branch name to the
baseURL
, which requires that we keep the branches
component in
there. Other VC schemes use a different approach towards branches and may
not require this artifact.
If your repository uses this same {PROJECT}/{BRANCH}/{FILEPATH}
naming
scheme, the following function will work:
def split_file_branches(path):
pieces = path.split('/')
if len(pieces) > 1 and pieces[0] == 'trunk':
return (None, '/'.join(pieces[1:]))
elif len(pieces) > 2 and pieces[0] == 'branches':
return ('/'.join(pieces[0:2]),
'/'.join(pieces[2:]))
else:
return None
In fact, this is the definition of the provided split_file_branches
function. So to have our Twisted-watching SVNPoller
follow
multiple branches, we would use this:
from buildbot.changes.svnpoller import SVNPoller, split_file_branches
c['change_source'] = SVNPoller("svn://svn.twistedmatrix.com/svn/Twisted",
split_file=split_file_branches)
Changes for all sorts of branches (with names like "branches/1.5.x"
, and
None
to indicate the trunk) will be delivered to the Schedulers. Each
Scheduler is then free to use or ignore each branch as it sees fit.
If you have multiple projects in the same repository your split function can attach a project name to the Change to help the Scheduler filter out unwanted changes:
from buildbot.changes.svnpoller import split_file_branches
def split_file_projects_branches(path):
if not "/" in path:
return None
project, path = path.split("/", 1)
f = split_file_branches(path)
if f:
info = dict(project=project, path=f[1])
if f[0]:
info['branch'] = f[0]
return info
return f
Again, this is provided by default. To use it you would do this:
from buildbot.changes.svnpoller import SVNPoller, split_file_projects_branches
c['change_source'] = SVNPoller(
svnurl="https://svn.amanda.sourceforge.net/svnroot/amanda/",
split_file=split_file_projects_branches)
Note here that we are monitoring at the root of the repository, and that within
that repository is a amanda
subdirectory which in turn has trunk
and
branches
. It is that amanda
subdirectory whose name becomes the
project
field of the Change.
BRANCHNAME/PROJECT/FILEPATH repositories¶
Another common way to organize a Subversion repository is to put the branch name at the top, and the projects underneath. This is especially frequent when there are a number of related sub-projects that all get released in a group.
For example, Divmod.org hosts a project named Nevow as
well as one named Quotient. In a checked-out Nevow tree there is a directory
named formless that contains a python source file named webform.py
.
This repository is accessible via webdav (and thus uses an http: scheme)
through the divmod.org hostname. There are many branches in this repository,
and they use a ({BRANCHNAME})/({PROJECT})
naming policy.
The fully-qualified SVN URL for the trunk version of webform.py
is
http://divmod.org/svn/Divmod/trunk/Nevow/formless/webform.py
.
The 1.5.x branch version of this file would have a URL of
http://divmod.org/svn/Divmod/branches/1.5.x/Nevow/formless/webform.py
.
The whole Nevow trunk would be checked out with
http://divmod.org/svn/Divmod/trunk/Nevow
, while the Quotient
trunk would be checked out using
http://divmod.org/svn/Divmod/trunk/Quotient
.
Now suppose we want to have an SVNPoller
that only cares about the
Nevow trunk. This case looks just like the {PROJECT}/{BRANCH}
layout
described earlier:
from buildbot.changes.svnpoller import SVNPoller
c['change_source'] = SVNPoller("http://divmod.org/svn/Divmod/trunk/Nevow")
But what happens when we want to track multiple Nevow branches? We
have to point our svnurl=
high enough to see all those
branches, but we also don't want to include Quotient changes (since
we're only building Nevow). To accomplish this, we must rely upon the
split_file
function to help us tell the difference between
files that belong to Nevow and those that belong to Quotient, as well
as figuring out which branch each one is on.
from buildbot.changes.svnpoller import SVNPoller
c['change_source'] = SVNPoller("http://divmod.org/svn/Divmod",
split_file=my_file_splitter)
The my_file_splitter
function will be called with repository-relative
pathnames like:
trunk/Nevow/formless/webform.py
- This is a Nevow file, on the trunk. We want the Change that includes this
to see a filename of
formless/webform.py
, and a branch ofNone
branches/1.5.x/Nevow/formless/webform.py
- This is a Nevow file, on a branch. We want to get
branch='branches/1.5.x'
andfilename='formless/webform.py'
. trunk/Quotient/setup.py
- This is a Quotient file, so we want to ignore it by having
my_file_splitter
returnNone
. branches/1.5.x/Quotient/setup.py
- This is also a Quotient file, which should be ignored.
The following definition for my_file_splitter
will do the job:
def my_file_splitter(path):
pieces = path.split('/')
if pieces[0] == 'trunk':
branch = None
pieces.pop(0) # remove 'trunk'
elif pieces[0] == 'branches':
pieces.pop(0) # remove 'branches'
# grab branch name
branch = 'branches/' + pieces.pop(0)
else:
return None # something weird
projectname = pieces.pop(0)
if projectname != 'Nevow':
return None # wrong project
return dict(branch=branch, path='/'.join(pieces))
If you later decide you want to get changes for Quotient as well you could replace the last 3 lines with simply:
return dict(project=projectname, branch=branch, path='/'.join(pieces))
Writing Change Sources¶
For some version-control systems, making Buildbot aware of new changes can be a challenge. If the pre-supplied classes in Change Sources are not sufficient, then you will need to write your own.
There are three approaches, one of which is not even a change source. The first option is to write a change source that exposes some service to which the version control system can "push" changes. This can be more complicated, since it requires implementing a new service, but delivers changes to Buildbot immediately on commit.
The second option is often preferable to the first: implement a notification service in an external process (perhaps one that is started directly by the version control system, or by an email server) and delivers changes to Buildbot via PBChangeSource. This section does not describe this particular approach, since it requires no customization within the buildmaster process.
The third option is to write a change source which polls for changes - repeatedly connecting to an external service to check for new changes. This works well in many cases, but can produce a high load on the version control system if polling is too frequent, and can take too long to notice changes if the polling is not frequent enough.
Writing a Notification-based Change Source¶
-
class
buildbot.changes.base.
ChangeSource
¶
A custom change source must implement
buildbot.interfaces.IChangeSource
.
The easiest way to do this is to subclass
buildbot.changes.base.ChangeSource
, implementing the describe
method to describe the instance. ChangeSource
is a Twisted service, so
you will need to implement the startService
and stopService
methods to control the means by which your change source receives
notifications.
When the class does receive a change, it should call
self.master.addChange(..)
to submit it to the buildmaster. This method
shares the same parameters as master.db.changes.addChange
, so consult the
API documentation for that function for details on the available arguments.
You will probably also want to set compare_attrs
to the list of object
attributes which Buildbot will use to compare one change source to another when
reconfiguring. During reconfiguration, if the new change source is different
from the old, then the old will be stopped and the new started.
Writing a Change Poller¶
-
class
buildbot.changes.base.
PollingChangeSource
¶
Polling is a very common means of seeking changes, so Buildbot supplies a
utility parent class to make it easier. A poller should subclass
buildbot.changes.base.PollingChangeSource
, which is a subclass of
ChangeSource
. This subclass implements the Service
methods,
and causes the poll
method to be called every self.pollInterval
seconds. This method should return a Deferred to signal its completion.
Aside from the service methods, the other concerns in the previous section apply here, too.
Writing a New Latent Buildslave Implementation¶
Writing a new latent buildslave should only require subclassing
buildbot.buildslave.AbstractLatentBuildSlave
and implementing
start_instance
and stop_instance
.
def start_instance(self):
# responsible for starting instance that will try to connect with this
# master. Should return deferred. Problems should use an errback. The
# callback value can be None, or can be an iterable of short strings to
# include in the "substantiate success" status message, such as
# identifying the instance that started.
raise NotImplementedError
def stop_instance(self, fast=False):
# responsible for shutting down instance. Return a deferred. If `fast`,
# we're trying to shut the master down, so callback as soon as is safe.
# Callback value is ignored.
raise NotImplementedError
See buildbot.ec2buildslave.EC2LatentBuildSlave
for an example, or see
the test example buildbot.test_slaves.FakeLatentBuildSlave
.
Custom Build Classes¶
The standard BuildFactory
object creates Build
objects
by default. These Builds will each execute a collection of BuildStep
s
in a fixed sequence. Each step can affect the results of the build,
but in general there is little intelligence to tie the different steps
together.
By setting the factory's buildClass
attribute to a different class, you can
instantiate a different build class. This might be useful, for example, to
create a build class that dynamically determines which steps to run. The
skeleton of such a project would look like:
class DynamicBuild(Build):
# .. override some methods
f = factory.BuildFactory()
f.buildClass = DynamicBuild
f.addStep(...)
Factory Workdir Functions¶
It is sometimes helpful to have a build's workdir determined at runtime based
on the parameters of the build. To accomplish this, set the workdir
attribute of the build factory to a callable. That callable will be invoked
with the SourceStamp
for the build, and should return the appropriate
workdir. Note that the value must be returned immediately - Deferreds are not
supported.
This can be useful, for example, in scenarios with multiple repositories submitting changes to BuildBot. In this case you likely will want to have a dedicated workdir per repository, since otherwise a sourcing step with mode = "update" will fail as a workdir with a working copy of repository A can't be "updated" for changes from a repository B. Here is an example how you can achieve workdir-per-repo:
def workdir(source_stamp):
return hashlib.md5 (source_stamp.repository).hexdigest()[:8]
build_factory = factory.BuildFactory()
build_factory.workdir = workdir
build_factory.addStep(Git(mode="update"))
# ...
builders.append ({'name': 'mybuilder',
'slavename': 'myslave',
'builddir': 'mybuilder',
'factory': build_factory})
The end result is a set of workdirs like
Repo1 => <buildslave-base>/mybuilder/a78890ba
Repo2 => <buildslave-base>/mybuilder/0823ba88
You could make the workdir
function compute other paths, based on
parts of the repo URL in the sourcestamp, or lookup in a lookup table
based on repo URL. As long as there is a permanent 1:1 mapping between
repos and workdir, this will work.
Writing New BuildSteps¶
While it is a good idea to keep your build process self-contained in the source code tree, sometimes it is convenient to put more intelligence into your Buildbot configuration.
One way to do this is to write a custom BuildStep
.
Once written, this Step can be used in the master.cfg
file.
The best reason for writing a custom BuildStep
is to better parse the results of the command being run.
For example, a BuildStep
that knows about JUnit could look at the logfiles to determine which tests had been run, how many passed and how many failed, and then report more detailed information than a simple rc==0
-based good/bad decision.
Buildbot has acquired a large fleet of build steps, and sports a number of knobs and hooks to make steps easier to write. This section may seem a bit overwhelming, but most custom steps will only need to apply one or two of the techniques outlined here.
For complete documentation of the build step interfaces, see BuildSteps.
Writing BuildStep Constructors¶
Build steps act as their own factories, so their constructors are a bit more complex than necessary.
In the configuration file, a BuildStep
object is instantiated, but because steps store state locally while executing, this object cannot be used during builds.
Consider the use of a BuildStep
in master.cfg
:
f.addStep(MyStep(someopt="stuff", anotheropt=1))
This creates a single instance of class MyStep
.
However, Buildbot needs a new object each time the step is executed.
An instance of BuildStep
remembers how it was constructed, and can create copies of itself.
When writing a new step class, then, keep in mind are that you cannot do anything "interesting" in the constructor -- limit yourself to checking and storing arguments.
It is customary to call the parent class's constructor with all otherwise-unspecified keyword arguments.
Keep a **kwargs
argument on the end of your options, and pass that up to the parent class's constructor.
The whole thing looks like this:
class Frobnify(LoggingBuildStep):
def __init__(self,
frob_what="frobee",
frob_how_many=None,
frob_how=None,
**kwargs):
# check
if frob_how_many is None:
raise TypeError("Frobnify argument how_many is required")
# override a parent option
kwargs['parentOpt'] = 'xyz'
# call parent
LoggingBuildStep.__init__(self, **kwargs)
# set Frobnify attributes
self.frob_what = frob_what
self.frob_how_many = how_many
self.frob_how = frob_how
class FastFrobnify(Frobnify):
def __init__(self,
speed=5,
**kwargs)
Frobnify.__init__(self, **kwargs)
self.speed = speed
Running Commands¶
To spawn a command in the buildslave, create a RemoteCommand
instance in your step's start
method and run it with runCommand
:
cmd = RemoteCommand(args)
d = self.runCommand(cmd)
To add a LogFile, use addLog
.
Make sure the log gets closed when it finishes.
When giving a Logfile to a RemoteShellCommand
, just ask it to close the log when the command completes:
log = self.addLog('output')
cmd.useLog(log, closeWhenFinished=True)
Updating Status¶
TBD
Capturing Logfiles¶
Each BuildStep has a collection of logfiles. Each one has a short
name, like stdio or warnings. Each LogFile
contains an
arbitrary amount of text, usually the contents of some output file
generated during a build or test step, or a record of everything that
was printed to stdout
/stderr
during the execution of some command.
These LogFile
s are stored to disk, so they can be retrieved later.
Each can contain multiple channels, generally limited to three
basic ones: stdout, stderr, and headers. For example, when a
ShellCommand runs, it writes a few lines to the headers channel to
indicate the exact argv strings being run, which directory the command
is being executed in, and the contents of the current environment
variables. Then, as the command runs, it adds a lot of stdout
and
stderr
messages. When the command finishes, a final header
line is added with the exit code of the process.
Status display plugins can format these different channels in different ways. For example, the web page shows LogFiles as text/html, with header lines in blue text, stdout in black, and stderr in red. A different URL is available which provides a text/plain format, in which stdout and stderr are collapsed together, and header lines are stripped completely. This latter option makes it easy to save the results to a file and run grep or whatever against the output.
Each BuildStep
contains a mapping (implemented in a python dictionary)
from LogFile
name to the actual LogFile
objects. Status plugins can
get a list of LogFiles to display, for example, a list of HREF links
that, when clicked, provide the full contents of the LogFile
.
Using LogFiles in custom BuildSteps¶
The most common way for a custom BuildStep
to use a LogFile
is to
summarize the results of a ShellCommand
(after the command has
finished running). For example, a compile step with thousands of lines
of output might want to create a summary of just the warning messages.
If you were doing this from a shell, you would use something like:
grep "warning:" output.log >warnings.log
In a custom BuildStep, you could instead create a warnings
LogFile
that contained the same text. To do this, you would add code to your
createSummary
method that pulls lines from the main output log
and creates a new LogFile
with the results:
def createSummary(self, log):
warnings = []
sio = StringIO.StringIO(log.getText())
for line in sio.readlines():
if "warning:" in line:
warnings.append()
self.addCompleteLog('warnings', "".join(warnings))
This example uses the addCompleteLog
method, which creates a
new LogFile
, puts some text in it, and then closes it, meaning
that no further contents will be added. This LogFile
will appear in
the HTML display under an HREF with the name warnings, since that
is the name of the LogFile
.
You can also use addHTMLLog
to create a complete (closed)
LogFile
that contains HTML instead of plain text. The normal LogFile
will be HTML-escaped if presented through a web page, but the HTML
LogFile
will not. At the moment this is only used to present a pretty
HTML representation of an otherwise ugly exception traceback when
something goes badly wrong during the BuildStep
.
In contrast, you might want to create a new LogFile
at the beginning
of the step, and add text to it as the command runs. You can create
the LogFile
and attach it to the build by calling addLog
, which
returns the LogFile
object. You then add text to this LogFile
by
calling methods like addStdout
and addHeader
. When you
are done, you must call the finish
method so the LogFile
can be
closed. It may be useful to create and populate a LogFile
like this
from a LogObserver
method - see Adding LogObservers.
The logfiles=
argument to ShellCommand
(see
ShellCommand
) creates new LogFile
s and fills them in realtime
by asking the buildslave to watch a actual file on disk. The
buildslave will look for additions in the target file and report them
back to the BuildStep
. These additions will be added to the LogFile
by
calling addStdout
. These secondary LogFiles can be used as the
source of a LogObserver just like the normal stdio
LogFile
.
Reading Logfiles¶
Once a LogFile
has been added to a
BuildStep
with
addLog
,
addCompleteLog
,
addHTMLLog
, or logfiles={}
,
your BuildStep
can retrieve it
by using getLog
:
class MyBuildStep(ShellCommand):
logfiles = @{ "nodelog": "_test/node.log" @}
def evaluateCommand(self, cmd):
nodelog = self.getLog("nodelog")
if "STARTED" in nodelog.getText():
return SUCCESS
else:
return FAILURE
Adding LogObservers¶
Most shell commands emit messages to stdout or stderr as they operate,
especially if you ask them nicely with a --verbose
flag of some
sort. They may also write text to a log file while they run. Your
BuildStep
can watch this output as it arrives, to keep track of how
much progress the command has made. You can get a better measure of
progress by counting the number of source files compiled or test cases
run than by merely tracking the number of bytes that have been written
to stdout. This improves the accuracy and the smoothness of the ETA
display.
To accomplish this, you will need to attach a LogObserver
to
one of the log channels, most commonly to the stdio
channel but
perhaps to another one which tracks a log file. This observer is given
all text as it is emitted from the command, and has the opportunity to
parse that output incrementally. Once the observer has decided that
some event has occurred (like a source file being compiled), it can
use the setProgress
method to tell the BuildStep
about the
progress that this event represents.
There are a number of pre-built LogObserver
classes that you
can choose from (defined in buildbot.process.buildstep
, and of
course you can subclass them to add further customization. The
LogLineObserver
class handles the grunt work of buffering and
scanning for end-of-line delimiters, allowing your parser to operate
on complete stdout
/stderr
lines. (Lines longer than a set maximum
length are dropped; the maximum defaults to 16384 bytes, but you can
change it by calling setMaxLineLength
on your
LogLineObserver
instance. Use sys.maxint
for effective
infinity.)
For example, let's take a look at the TrialTestCaseCounter
,
which is used by the Trial
step to count test cases as they are run.
As Trial executes, it emits lines like the following:
buildbot.test.test_config.ConfigTest.testDebugPassword ... [OK]
buildbot.test.test_config.ConfigTest.testEmpty ... [OK]
buildbot.test.test_config.ConfigTest.testIRC ... [FAIL]
buildbot.test.test_config.ConfigTest.testLocks ... [OK]
When the tests are finished, trial emits a long line of ====== and then some lines which summarize the tests that failed. We want to avoid parsing these trailing lines, because their format is less well-defined than the [OK] lines.
The parser class looks like this:
from buildbot.process.buildstep import LogLineObserver
class TrialTestCaseCounter(LogLineObserver):
_line_re = re.compile(r'^([\w\.]+) \.\.\. \[([^\]]+)\]$')
numTests = 0
finished = False
def outLineReceived(self, line):
if self.finished:
return
if line.startswith("=" * 40):
self.finished = True
return
m = self._line_re.search(line.strip())
if m:
testname, result = m.groups()
self.numTests += 1
self.step.setProgress('tests', self.numTests)
This parser only pays attention to stdout, since that's where trial
writes the progress lines. It has a mode flag named finished
to
ignore everything after the ====
marker, and a scary-looking
regular expression to match each line while hopefully ignoring other
messages that might get displayed as the test runs.
Each time it identifies a test has been completed, it increments its counter and delivers the new progress value to the step with @code{self.step.setProgress}. This class is specifically measuring progress along the tests metric, in units of test cases (as opposed to other kinds of progress like the output metric, which measures in units of bytes). The Progress-tracking code uses each progress metric separately to come up with an overall completion percentage and an ETA value.
To connect this parser into the Trial
build step,
Trial.__init__
ends with the following clause:
# this counter will feed Progress along the 'test cases' metric
counter = TrialTestCaseCounter()
self.addLogObserver('stdio', counter)
self.progressMetrics += ('tests',)
This creates a TrialTestCaseCounter
and tells the step that the
counter wants to watch the stdio
log. The observer is
automatically given a reference to the step in its step
attribute.
Using Properties¶
In custom BuildSteps
, you can get and set the build properties with
the getProperty
/setProperty
methods. Each takes a string
for the name of the property, and returns or accepts an
arbitrary object. For example:
class MakeTarball(ShellCommand):
def start(self):
if self.getProperty("os") == "win":
self.setCommand([ ... ]) # windows-only command
else:
self.setCommand([ ... ]) # equivalent for other systems
ShellCommand.start(self)
Remember that properties set in a step may not be available until the next step
begins. In particular, any Property
or Interpolate
instances for the current step are interpolated before the start
method
begins.
BuildStep URLs¶
Each BuildStep has a collection of links. Like its collection of LogFiles, each link has a name and a target URL. The web status page creates HREFs for each link in the same box as it does for LogFiles, except that the target of the link is the external URL instead of an internal link to a page that shows the contents of the LogFile.
These external links can be used to point at build information hosted
on other servers. For example, the test process might produce an
intricate description of which tests passed and failed, or some sort
of code coverage data in HTML form, or a PNG or GIF image with a graph
of memory usage over time. The external link can provide an easy way
for users to navigate from the buildbot's status page to these
external web sites or file servers. Note that the step itself is
responsible for insuring that there will be a document available at
the given URL (perhaps by using scp to copy the HTML output
to a ~/public_html/
directory on a remote web server). Calling
addURL
does not magically populate a web server.
To set one of these links, the BuildStep
should call the addURL
method with the name of the link and the target URL. Multiple URLs can
be set.
In this example, we assume that the make test
command causes
a collection of HTML files to be created and put somewhere on the
coverage.example.org web server, in a filename that incorporates the
build number.
class TestWithCodeCoverage(BuildStep):
command = ["make", "test",
Interpolate("buildnum=%(prop:buildnumber)s")]
def createSummary(self, log):
buildnumber = self.getProperty("buildnumber")
url = "http://coverage.example.org/builds/%s.html" % buildnumber
self.addURL("coverage", url)
You might also want to extract the URL from some special message output by the build process itself:
class TestWithCodeCoverage(BuildStep):
command = ["make", "test",
Interpolate("buildnum=%(prop:buildnumber)s")]
def createSummary(self, log):
output = StringIO(log.getText())
for line in output.readlines():
if line.startswith("coverage-url:"):
url = line[len("coverage-url:"):].strip()
self.addURL("coverage", url)
return
Note that a build process which emits both stdout
and stderr
might
cause this line to be split or interleaved between other lines. It
might be necessary to restrict the getText
call to only stdout with
something like this:
output = StringIO("".join([c[1]
for c in log.getChunks()
if c[0] == LOG_CHANNEL_STDOUT]))
Of course if the build is run under a PTY, then stdout and stderr will be merged before the buildbot ever sees them, so such interleaving will be unavoidable.
A Somewhat Whimsical Example¶
Let's say that we've got some snazzy new unit-test framework called Framboozle. It's the hottest thing since sliced bread. It slices, it dices, it runs unit tests like there's no tomorrow. Plus if your unit tests fail, you can use its name for a Web 2.1 startup company, make millions of dollars, and hire engineers to fix the bugs for you, while you spend your afternoons lazily hang-gliding along a scenic pacific beach, blissfully unconcerned about the state of your tests. [1]
To run a Framboozle-enabled test suite, you just run the 'framboozler' command from the top of your source code tree. The 'framboozler' command emits a bunch of stuff to stdout, but the most interesting bit is that it emits the line "FNURRRGH!" every time it finishes running a test case You'd like to have a test-case counting LogObserver that watches for these lines and counts them, because counting them will help the buildbot more accurately calculate how long the build will take, and this will let you know exactly how long you can sneak out of the office for your hang-gliding lessons without anyone noticing that you're gone.
This will involve writing a new BuildStep
(probably named
"Framboozle") which inherits from ShellCommand
. The BuildStep
class
definition itself will look something like this:
from buildbot.steps.shell import ShellCommand
from buildbot.process.buildstep import LogLineObserver
class FNURRRGHCounter(LogLineObserver):
numTests = 0
def outLineReceived(self, line):
if "FNURRRGH!" in line:
self.numTests += 1
self.step.setProgress('tests', self.numTests)
class Framboozle(ShellCommand):
command = ["framboozler"]
def __init__(self, **kwargs):
ShellCommand.__init__(self, **kwargs) # always upcall!
counter = FNURRRGHCounter())
self.addLogObserver('stdio', counter)
self.progressMetrics += ('tests',)
So that's the code that we want to wind up using. How do we actually deploy it?
You have a couple of different options.
Option 1: The simplest technique is to simply put this text
(everything from START to FINISH) in your master.cfg
file, somewhere
before the BuildFactory
definition where you actually use it in a
clause like:
f = BuildFactory()
f.addStep(SVN(svnurl="stuff"))
f.addStep(Framboozle())
Remember that master.cfg
is secretly just a python program with one
job: populating the BuildmasterConfig
dictionary. And python programs
are allowed to define as many classes as they like. So you can define
classes and use them in the same file, just as long as the class is
defined before some other code tries to use it.
This is easy, and it keeps the point of definition very close to the point of use, and whoever replaces you after that unfortunate hang-gliding accident will appreciate being able to easily figure out what the heck this stupid "Framboozle" step is doing anyways. The downside is that every time you reload the config file, the Framboozle class will get redefined, which means that the buildmaster will think that you've reconfigured all the Builders that use it, even though nothing changed. Bleh.
Option 2: Instead, we can put this code in a separate file, and import
it into the master.cfg file just like we would the normal buildsteps
like ShellCommand
and SVN
.
Create a directory named ~/lib/python, put everything from START to
FINISH in ~/lib/python/framboozle.py
, and run your buildmaster using:
PYTHONPATH=~/lib/python buildbot start MASTERDIR
or use the Makefile.buildbot
to control the way
buildbot start
works. Or add something like this to
something like your ~/.bashrc
or ~/.bash_profile
or ~/.cshrc
:
export PYTHONPATH=~/lib/python
Once we've done this, our master.cfg
can look like:
from framboozle import Framboozle
f = BuildFactory()
f.addStep(SVN(svnurl="stuff"))
f.addStep(Framboozle())
or:
import framboozle
f = BuildFactory()
f.addStep(SVN(svnurl="stuff"))
f.addStep(framboozle.Framboozle())
(check out the python docs for details about how "import" and "from A import B" work).
What we've done here is to tell python that every time it handles an
"import" statement for some named module, it should look in our
~/lib/python/
for that module before it looks anywhere else. After our
directories, it will try in a bunch of standard directories too
(including the one where buildbot is installed). By setting the
PYTHONPATH
environment variable, you can add directories to the front
of this search list.
Python knows that once it "import"s a file, it doesn't need to
re-import it again. This means that reconfiguring the buildmaster
(with buildbot reconfig
, for example) won't make it think the
Framboozle class has changed every time, so the Builders that use it
will not be spuriously restarted. On the other hand, you either have
to start your buildmaster in a slightly weird way, or you have to
modify your environment to set the PYTHONPATH
variable.
Option 3: Install this code into a standard python library directory
Find out what your python's standard include path is by asking it:
80:warner@luther% python
Python 2.4.4c0 (#2, Oct 2 2006, 00:57:46)
[GCC 4.1.2 20060928 (prerelease) (Debian 4.1.1-15)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import sys
>>> import pprint
>>> pprint.pprint(sys.path)
['',
'/usr/lib/python24.zip',
'/usr/lib/python2.4',
'/usr/lib/python2.4/plat-linux2',
'/usr/lib/python2.4/lib-tk',
'/usr/lib/python2.4/lib-dynload',
'/usr/local/lib/python2.4/site-packages',
'/usr/lib/python2.4/site-packages',
'/usr/lib/python2.4/site-packages/Numeric',
'/var/lib/python-support/python2.4',
'/usr/lib/site-python']
In this case, putting the code into
/usr/local/lib/python2.4/site-packages/framboozle.py would work just
fine. We can use the same master.cfg
import framboozle
statement as
in Option 2. By putting it in a standard include directory (instead of
the decidedly non-standard ~/lib/python
), we don't even have to set
PYTHONPATH
to anything special. The downside is that you probably have
to be root to write to one of those standard include directories.
Option 4: Submit the code for inclusion in the Buildbot distribution
Make a fork of buildbot on http://github.com/djmitche/buildbot or post a patch in a bug at http://buildbot.net. In either case, post a note about your patch to the mailing list, so others can provide feedback and, eventually, commit it.
from buildbot.steps import framboozle f = BuildFactory() f.addStep(SVN(svnurl="stuff")) f.addStep(framboozle.Framboozle())
And then you don't even have to install framboozle.py anywhere on your system,
since it will ship with Buildbot. You don't have to be root, you don't have to
set PYTHONPATH
. But you do have to make a good case for Framboozle
being worth going into the main distribution, you'll probably have to provide
docs and some unit test cases, you'll need to figure out what kind of beer the
author likes (IPA's and Stouts for Dustin), and then you'll have to wait until
the next release. But in some environments, all this is easier than getting
root on your buildmaster box, so the tradeoffs may actually be worth it.
Putting the code in master.cfg (1) makes it available to that buildmaster instance. Putting it in a file in a personal library directory (2) makes it available for any buildmasters you might be running. Putting it in a file in a system-wide shared library directory (3) makes it available for any buildmasters that anyone on that system might be running. Getting it into the buildbot's upstream repository (4) makes it available for any buildmasters that anyone in the world might be running. It's all a matter of how widely you want to deploy that new class.
Writing New Status Plugins¶
Each status plugin is an object which provides the
twisted.application.service.IService
interface, which creates a
tree of Services with the buildmaster at the top [not strictly true].
The status plugins are all children of an object which implements
buildbot.interfaces.IStatus
, the main status object. From this
object, the plugin can retrieve anything it wants about current and
past builds. It can also subscribe to hear about new and upcoming
builds.
Status plugins which only react to human queries (like the Waterfall
display) never need to subscribe to anything: they are idle until
someone asks a question, then wake up and extract the information they
need to answer it, then they go back to sleep. Plugins which need to
act spontaneously when builds complete (like the MailNotifier
plugin)
need to subscribe to hear about new builds.
If the status plugin needs to run network services (like the HTTP
server used by the Waterfall plugin), they can be attached as Service
children of the plugin itself, using the IServiceCollection
interface.
[1] | framboozle.com is still available. Remember, I get 10% :). |