This page documents the latest, unreleased version of Buildbot. For documentation for released versions, see http://buildbot.net/buildbot/docs.
Build properties are a generalized way to provide configuration information to build steps; see Build Properties for the conceptual overview of properties.
Some build properties come from external sources and are set before the build begins; others are set during the build, and available for later steps. The sources for properties are:
- global configuration -- These properties apply to all builds.
- schedulers -- A scheduler can specify properties that become available to all builds it starts.
- changes -- A change can have properties attached to it, supplying extra information gathered by the change source. This is most commonly used with the sendchange command.
- forced builds -- The "Force Build" form allows users to specify properties
- buildslaves -- A buildslave can pass properties on to the builds it performs.
- builds -- A build automatically sets a number of properties on itself.
- builders -- A builder can set properties on all the builds it runs.
- steps -- The steps of a build can set properties that are available to subsequent steps. In particular, source steps set the got_revision property.
If the same property is supplied in multiple places, the final appearance takes precedence. For example, a property set in a builder configuration will override one supplied by a scheduler.
Properties are stored internally in JSON format, so they are limited to basic types of data: numbers, strings, lists, and dictionaries.
Common Build Properties¶
The following build properties are set when the build is started, and are available to all steps.
This property is set when a Source step checks out the source tree, and provides the revision that was actually obtained from the VC system. In general this should be the same as revision, except for non-absolute sourcestamps, where got_revision indicates what revision was current when the checkout was performed. This can be used to rebuild the same source code later.
For some VC systems (Darcs in particular), the revision is a large string containing newlines, and is not suitable for interpolation into a filename.
For multi-codebase builds (where codebase is not the default ''), this property is a dictionary, keyed by codebase.
- This is a string that indicates which Builder the build was a part of. The combination of buildername and buildnumber uniquely identify a build.
- Each build gets a number, scoped to the Builder (so the first build performed on any given Builder will have a build number of 0). This integer property contains the build's number.
- This is a string which identifies which buildslave the build is running on.
- If the build was started from a scheduler, then this property will contain the name of that scheduler.
- The absolute path of the base working directory on the slave, of the current builder.
For single codebase builds, where the codebase is '', the following Source Stamp Attributes are also available as properties: branch, revision, repository, and project .
Source Stamp Attributes¶
branch revision repository project codebase
For details of these attributes see Concepts.
This attribute is a list of dictionaries reperesnting the changes that make up this sourcestamp.
Using Properties in Steps¶
For the most part, properties are used to alter the behavior of build steps during a build. This is done by annotating the step definition in master.cfg with placeholders. When the step is executed, these placeholders will be replaced using the current values of the build properties.
Properties are defined while a build is in progress; their values are not available when the configuration file is parsed. This can sometimes confuse newcomers to Buildbot! In particular, the following is a common error:
if Property('release_train') == 'alpha': f.addStep(...)
This does not work because the value of the property is not available when the if statement is executed. However, Python will not detect this as an error - you will just never see the step added to the factory.
You can use build properties in most step parameters. Please file bugs for any parameters which do not accept properties.
The simplest form of annotation is to wrap the property name with Property:
from buildbot.steps.shell import ShellCommand from buildbot.process.properties import Property f.addStep(ShellCommand(command=[ 'echo', 'buildername:', Property('buildername') ]))
You can specify a default value by passing a default keyword argument:
f.addStep(ShellCommand(command=[ 'echo', 'warnings:', Property('warnings', default='none') ]))
The default value is used when the property doesn't exist, or when the value is something Python regards as False. The defaultWhenFalse argument can be set to False to force buildbot to use the default argument only if the parameter is not set:
f.addStep(ShellCommand(command=[ 'echo', 'warnings:', Property('warnings', default='none', defaultWhenFalse=False) ]))
The default value can reference other properties, e.g.,
Property can only be used to replace an entire argument: in the example above, it replaces an argument to echo. Often, properties need to be interpolated into strings, instead. The tool for that job is Interpolate.
The more common pattern is to use Python dictionary-style string interpolation by using the %(prop:<propname>)s syntax. In this form, the property name goes in the parentheses, as above. A common mistake is to omit the trailing "s", leading to a rather obscure error from Python ("ValueError: unsupported format character").
from buildbot.steps.shell import ShellCommand from buildbot.process.properties import Interpolate f.addStep(ShellCommand(command=[ 'make', Interpolate('REVISION=%(prop:got_revision)s'), 'dist' ]))
This example will result in a make command with an argument like REVISION=12098.
The syntax of dictionary-style interpolation is a selector, followed by a colon, followed by a selector specific key, optionally followed by a colon and a string indicating how to interpret the value produced by the key.
The following selectors are supported.
- The key is the name of a property.
- The key is a codebase and source stamp attribute, separated by a colon.
- The key refers to a keyword argument passed to Interpolate.
The following ways of interpreting the value are available.
- If the key exists, substitute its value; otherwise, substitute replacement. replacement may be empty (%(prop:propname:-)s). This is the default.
- Like -replacement, but only substitutes the value of the key if it is something Python regards as True. Python considers None, 0, empty lists, and the empty string to be false, so such values will be replaced by replacement.
- If the key exists, substitute replacement; otherwise, substitute an empty string.
- Ternary substitution, depending on either the key being present (with ?, similar to +) or being True (with #?, like ~). Notice that there is a pipe immediately following the question mark and between the two substitution alternatives. The character that follows the question mark is used as the delimiter between the two alternatives. In the above examples, it is a pipe, but any character other than ( can be used.
Although these are similar to shell substitutions, no other substitutions are currently supported.
from buildbot.steps.shell import ShellCommand from buildbot.process.properties import Interpolate f.addStep(ShellCommand(command=[ 'make', Interpolate('REVISION=%(prop:got_revision:-%(src::revision:-unknown)s)s'), 'dist' ]))
In addition, Interpolate supports using positional string interpolation. Here, %s is used as a placeholder, and the substitutions (which may themselves be placeholders), are given as subsequent arguments:
Like Python, you can use either positional interpolation or dictionary-style interpolation, not both. Thus you cannot use a string like Interpolate("foo-%(src::revision)s-%s", "branch").
While Interpolate can handle many simple cases, and even some common conditionals, more complex cases are best handled with Python code. The renderer decorator creates a renderable object that will be replaced with the result of the function, called when the step it's passed to begins. The function receives an IProperties object, which it can use to examine the values of any and all properties. For example:
from buildbot.process import properties @properties.renderer def makeCommand(props): command = [ 'make' ] cpus = props.getProperty('CPUs') if cpus: command += [ '-j', str(cpus+1) ] else: command += [ '-j', '2' ] command += [ 'all' ] return command f.addStep(ShellCommand(command=makeCommand))
You can think of renderer as saying "call this function when the step starts".
If nested list should be flatten for some renderables, FlattenList could be used. For example:
f.addStep(ShellCommand(command=[ 'make' ], descriptionDone=FlattenList([ 'make ', [ 'done' ]])))
descriptionDone would be set to [ 'make', 'done' ] when the ShellCommand executes. This is useful when a list-returning property is used in renderables.
ShellCommand automatically flattens nested lists in its command argument, so there is no need to use FlattenList for it.
This placeholder is deprecated. It is an older version of Interpolate. It exists for compatibility with older configs.
The simplest use of this class is with positional string interpolation. Here, %s is used as a placeholder, and property names are given as subsequent arguments:
from buildbot.steps.shell import ShellCommand from buildbot.process.properties import WithProperties f.addStep(ShellCommand( command=["tar", "czf", WithProperties("build-%s-%s.tar.gz", "branch", "revision"), "source"]))
If this BuildStep were used in a tree obtained from Git, it would create a tarball with a name like build-master-a7d3a333db708e786edb34b6af646edd8d4d3ad9.tar.gz.
The more common pattern is to use Python dictionary-style string interpolation by using the %(propname)s syntax. In this form, the property name goes in the parentheses, as above. A common mistake is to omit the trailing "s", leading to a rather obscure error from Python ("ValueError: unsupported format character").
from buildbot.steps.shell import ShellCommand from buildbot.process.properties import WithProperties f.addStep(ShellCommand(command=[ 'make', WithProperties('REVISION=%(got_revision)s'), 'dist' ]))
This example will result in a make command with an argument like REVISION=12098.
The dictionary-style interpolation supports a number of more advanced syntaxes in the parentheses.
- If propname exists, substitute its value; otherwise, substitute replacement. replacement may be empty (%(propname:-)s)
- Like propname:-replacement, but only substitutes the value of property propname if it is something Python regards as True. Python considers None, 0, empty lists, and the empty string to be false, so such values will be replaced by replacement.
- If propname exists, substitute replacement; otherwise, substitute an empty string.
Although these are similar to shell substitutions, no other substitutions are currently supported, and replacement in the above cannot contain more substitutions.
Note: like Python, you can use either positional interpolation or dictionary-style interpolation, not both. Thus you cannot use a string like WithProperties("foo-%(revision)s-%s", "branch").
If the options described above are not sufficient, more complex substitutions can be achieved by writing custom renderables.
Renderables are objects providing the IRenderable interface. That interface is simple - objects must provide a getRenderingFor method. The method should take one argument - an IProperties provider - and should return a string or a deferred firing with a string. Pass instances of the class anywhere other renderables are accepted. For example:
class DetermineFoo(object): implements(IRenderable) def getRenderingFor(self, props): if props.hasProperty('bar'): return props['bar'] elif props.hasProperty('baz'): return props['baz'] return 'qux' ShellCommand(command=['echo', DetermineFoo()])
or, more practically,
class Now(object): implements(IRenderable) def getRenderingFor(self, props): return time.clock() ShellCommand(command=['make', Interpolate('TIME=%(kw:now)s', now=Now())])
This is equivalent to:
@renderer def now(props): return time.clock() ShellCommand(command=['make', Interpolate('TIME=%(kw:now)s', now=now)])
Note that a custom renderable must be instantiated (and its constructor can take whatever arguments you'd like), whereas a function decorated with renderer can be used directly.