Wherever possible, Buildbot components should access configuration information
as needed from the canonical source,
master.config, which is an instance of
MasterConfig. For example, components should not keep a copy of
buildbotURL locally, as this value may change throughout the lifetime
of the master.
The master object makes much of the configuration available from an object named
master.config. Configuration is stored as attributes of this object. Where possible, other Buildbot components should access this configuration directly and not cache the configuration values anywhere else. This avoids the need to ensure that update-from-configuration methods are called on a reconfig.
Aside from validating the configuration, this class handles any backward-compatibility issues - renamed parameters, type changes, and so on - removing those concerns from other parts of Buildbot.
This class may be instantiated directly, creating an entirely default configuration, or via
loadConfig, which will load the configuration from a config file.
The following attributes are available from this class, representing the current configuration. This includes a number of global parameters:
A callable, or None, used to determine the codebase from an incoming
The remaining attributes contain compound configuration structures, usually dictionaries:
Validation regular expressions, a dictionary from
validation. It is safe to assume that all expected keys are present.
Cachesare always available; other keys should use
Loading of the configuration file is generally triggered by the master, using the following methods:
- basedir (string) -- directory to which config is relative
- filename (string) -- the configuration file to load
ConfigErrorsif any errors occur
Load the configuration in the given file. Aside from syntax errors, this will also detect a number of semantic errors such as multiple schedulers with the same name.
The filename is treated as relative to the basedir, if it is not absolute.
This class parameterizes configuration of builders; see Builder Configuration for its arguments. The constructor checks for errors and applies defaults, and sets the properties described here. Most are simply copied from the constructor argument of the same name.
Users may subclass this class to add defaults, for example.
The builder's name.
The builder's factory.
The builder's slave names (a list, regardless of whether the names were specified with
The builder's builddir.
The builder's slave-side builddir.
The builder's category.
The builder's nextSlave callable.
The builder's nextBuild callable.
The builder's canStartBuild callable.
The builder's locks.
The builder's environmnet variables.
The builder's properties, as a dictionary.
The builder's mergeRequests callable.
The builder's description, displayed in the web status.
If any errors are encountered while loading the configuration
should be called. This can occur both in the configuration-loading code,
and in the constructors of any objects that are instantiated in the
configuration - change sources, slaves, schedulers, build steps, and so on.
Parameters: error -- error to report Raises:
ConfigErrorsif called at build-time
This function reports a configuration error. If a config file is being loaded, then the function merely records the error, and allows the rest of the configuration to be loaded. At any other time, it raises
ConfigErrors. This is done so all config errors can be reported, rather than just the first.
Parameters: errors (list) -- errors to report
This exception represents errors in the configuration. It supports reporting multiple errors to the user simultaneously, e.g., when several consistency checks fail.
A list of detected errors, each given as a string.
Parameters: msg (string) -- the message to add
Add another error message to the (presumably not-yet-raised) exception.
When the buildmaster receives a signal to begin a reconfig, it re-reads the
configuration file, generating a new
MasterConfig instance, and
then notifies all of its child services via the reconfig mechanism described
below. The master ensures that at most one reconfiguration is taking place at
See Master Organization for the structure of the Buildbot service tree.
To simplify initialization, a reconfiguration is performed immediately on
master startup. As a result, services only need to implement their
configuration handling once, and can use
startService for initialization.
See below for instructions on implementing configuration of common types of components in Buildbot.
Because Buildbot uses a pure-Python configuration file, it is not possible to support all forms of reconfiguration. In particular, when the configuration includes custom subclasses or modules, reconfiguration can turn up some surprising behaviors due to the dynamic nature of Python. The reconfig support in Buildbot is intended for "intermediate" uses of the software, where there are fewer surprises.
Parameters: new_config (
MasterConfig) -- new master configuration
This method notifies the service that it should make any changes necessary to adapt to the new configuration values given.
This method will be called automatically after a service is started.
It is generally too late at this point to roll back the reconfiguration, so if possible any errors should be detected in the
MasterConfigimplementation. Errors are handled as best as possible and communicated back to the top level invocation, but such errors may leave the master in an inconsistent state.
ConfigErrorsexceptions will be displayed appropriately to the user on startup.
Subclasses should always call the parent class's implementation. For
MultiServiceinstances, this will call any child services'
reconfigServicemethods, as appropriate. This will be done sequentially, such that the Deferred from one service must fire before the next service is reconfigured.
Child services are reconfigured in order of decreasing priority. The default priority is 128, so a service that must be reconfigured before others should be given a higher priority.
When reconfiguring, there is no method by which Buildbot can determine that a
ChangeSource represents the same source
as an existing
ChangeSource, but with
different configuration parameters. As a result, the change source manager
compares the lists of existing and new change sources using equality, stops any
existing sources that are not in the new list, and starts any new change
sources that do not already exist.
If a change source does not make reference to any global configuration
parameters, then there is no need to inherit
ReconfigurableServiceMixin, as a simple comparison and
stopService will be sufficient.
If the change source does make reference to global values, e.g., as default
values for its parameters, then it must inherit
ReconfigurableServiceMixin to support the case where the global
Schedulers have names, so Buildbot can determine whether a scheduler has been
added, removed, or changed during a reconfig. Old schedulers will be stopped,
new schedulers will be started, and both new and existing schedulers will see a
reconfigService, if such a
method exists. For backward compatibility, schedulers which do not support
reconfiguration will be stopped, and the new scheduler started, when their
If, during a reconfiguration, a new and old scheduler's fully qualified class names differ, then the old class will be stopped and the new class started. This supports the case when a user changes, for example, a Nightly scheduler to a Periodic scheduler without changing the name.
Because Buildbot uses
instances directly in the configuration file, a reconfigured scheduler must
extract its new configuration information from another instance of itself.
BaseScheduler implements a helper method,
which will return the new instance of the scheduler in the given
Custom subclasses are most often defined directly in the configuration file, or
in a Python module that is reloaded with
reload every time the
configuration is loaded. Because of the dynamic nature of Python, this creates
a new object representing the subclass every time the configuration is loaded
-- even if the class definition has not changed.
Note that if a scheduler's class changes in a reconfig, but the scheduler's name does not, it will still be treated as a reconfiguration of the existing scheduler. This means that implementation changes in custom scheduler subclasses will not be activated with a reconfig. This behavior avoids stopping and starting such schedulers on every reconfig, but can make development difficult.
One workaround for this is to change the name of the scheduler before each reconfig - this will cause the old scheduler to be stopped, and the new scheduler (with the new name and class) to be started.
Similar to schedulers, slaves are specified by name, so new and old
configurations are first compared by name, and any slaves to be added or
removed are noted. Slaves for which the fully-qualified class name has changed
are also added and removed. All slaves have their
reconfigService method called.
This method takes care of the basic slave attributes, including changing the PB
registration if necessary. Any subclasses that add configuration parameters
update those parameters. As with Schedulers, because the
AbstractBuildSlave instance is given directly
in the configuration, on reconfig instances must extract the configuration from
a new instance. The
can be used to find the new instance.
Since user managers are rarely used, and their purpose is unclear, they are always stopped and re-started on every reconfig. This may change in figure versions.
At every reconfig, all status listeners are stopped and new versions started.