+# Permission is hereby granted, free of charge, to any person obtaining a
+# copy of this software and associated documentation files (the "Software"),
+# to deal in the Software without restriction, including without limitation
+# the rights to use, copy, modify, merge, publish, distribute, sublicense,
+# and/or sell copies of the Software, and to permit persons to whom the
+# Software is furnished to do so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be included in
+# all copies or substantial portions of the Software.
+
=head1 NAME
collectd-python - Documentation of collectd's C<python plugin>
Python-script every time you want to read a value with the C<exec plugin> (see
L<collectd-exec(5)>) and provides a lot more functionality, too.
+At least python I<version 2.3> is required.
+
=head1 CONFIGURATION
=over 4
Loads the Python plugin I<Plugin>. Unlike most other LoadPlugin lines, this one
should be a block containing the line "Globals true". This will cause collectd
to export the name of all objects in the python interpreter for all plugins to
-see. If you don't do this or your platform does not support it, the embeded
-interpreter will start anywa but you won't be able to load certain python
+see. If you don't do this or your platform does not support it, the embedded
+interpreter will start anyway but you won't be able to load certain python
modules, e.g. "time".
-=item B<MudulePath> I<Name>
+=item B<Encoding> I<Name>
+
+The default encoding for Unicode objects you pass to collectd. If you omit this
+option it will default to B<ascii> on I<Python 2> and B<utf-8> on I<Python 3>.
+This is hardcoded in Python and will ignore everything else, including your
+locale.
+
+=item B<ModulePath> I<Name>
Appends I<Name> to B<sys.path>. You won't be able to import any scripts you
-wrote unless they are located in one of the directuries in this list. Please
-note that it only has effect on plugins loaded after this option.
+wrote unless they are located in one of the directories in this list. Please
+note that it only has effect on plugins loaded after this option. You can
+use multiple B<ModulePath> lines to add more than one directory.
=item B<LogTraces> I<bool>
=item B<Interactive> I<bool>
-This option will causethe module to launch an interactive python interpreter
+This option will cause the module to launch an interactive python interpreter
that reads from and writes to the terminal. Note that collectd will terminate
right after starting up if you try to run it as a daemon while this option is
enabled to make sure to start collectd with the B<-f> option.
This interactive session will behave slightly differently from a daemonized
collectd script as well as from a normal python interpreter:
-1. collectd will try to import the B<readline> module to give you a decent
-way of entering your commmands. The daemonized collectd won't do that.
-2. collectd will block SIGINT. Pressing Ctrl+C will usually cause collectd to
-shut down. This would be problematic in an interactive session, therefore this
-signal will be blocked. You can still use it to interrupt syscalls like sleep
-and pause but it won't generate a KeyboardInterrupt exception either.
-To quit collectd send EOF (press Ctrl+D at the beginning of a new line).
+=over 4
+
+=item
+
+B<1.> collectd will try to import the B<readline> module to give you a decent
+way of entering your commands. The daemonized collectd won't do that.
+
+=item
+
+B<2.> collectd will block I<SIGINT>. Pressing I<Ctrl+C> will usually cause
+collectd to shut down. This would be problematic in an interactive session,
+therefore this signal will be blocked. You can still use it to interrupt
+syscalls like sleep and pause but it won't generate a I<KeyboardInterrupt>
+exception either.
+
+To quit collectd send I<EOF> (press I<Ctrl+D> at the beginning of a new line).
+
+=item
+
+B<3.> collectd handles I<SIGCHLD>. This means that python won't be able to
+determine the return code of spawned processes with system(), popen() and
+subprocess. This will result in python not using external programs like less
+to display help texts. You can override this behavior with the B<PAGER>
+environment variable, e.g. I<export PAGER=less> before starting collectd.
+Depending on your version of python this might or might not result in an
+B<OSError> exception which can be ignored.
+
+If you really need to spawn new processes from python you can register an init
+callback and reset the action for SIGCHLD to the default behavior. Please note
+that this I<will> break the exec plugin. Do not even load the exec plugin if
+you intend to do this!
+
+There is an example script located in B<contrib/python/getsigchld.py> to do
+this. If you import this from I<collectd.conf> SIGCHLD will be handled
+normally and spawning processes from python will work as intended.
+
+=back
=item E<lt>B<Module> I<Name>E<gt> block
This block may be used to pass on configuration settings to a Python module.
-The configuration is converted into an instance of the B<Config> class which
-is passed to the registered configuration callback. See below for details about
+The configuration is converted into an instance of the B<Config> class which is
+passed to the registered configuration callback. See below for details about
the B<Config> class and how to register callbacks.
The I<name> identifies the callback.
=back
+=head1 STRINGS
+
+There are a lot of places where strings are send from collectd to python and
+from python to collectd. How exactly this works depends on wheather byte or
+unicode strings or python2 or python3 are used.
+
+Python2 has I<str>, which is just bytes, and I<unicode>. Python3 has I<str>,
+which is a unicode object, and I<bytes>.
+
+When passing strings from python to collectd all of these object are supported
+in all places, however I<str> should be used if possible. These strings must
+not contain a NUL byte. Ignoring this will result in a I<TypeError> exception.
+If a byte string was used it will be used as is by collectd. If a unicode
+object was used it will be encoded using the default encoding (see above). If
+this is not possible python will raise a I<UnicodeEncodeError> exception.
+
+Wenn passing strings from collectd to python the behavior depends on the
+python version used. Python2 will always receive a I<str> object. Python3 will
+usually receive a I<str> object as well, however the original string will be
+decoded to unicode using the default encoding. If this fails because the
+string is not a valid sequence for this encoding a I<bytes> object will be
+returned instead.
+
=head1 WRITING YOUR OWN PLUGINS
Writing your own plugins is quite simple. collectd manages plugins by means of
B<register_config> method - see below.
Python thread support has not been initialized at this point so do not use any
-threading functions at this point!
+threading functions here!
=item init functions
Any function (except log functions) may set throw an exception in case of any
errors. The exception will be passed on to the user using collectd's logging
-mechanism. If a log callback throws an exception it will be printed to stderr
-instead.
+mechanism. If a log callback throws an exception it will be printed to standard
+error instead.
See the documentation of the various B<register_> methods in the section
"FUNCTIONS" below for the number and types of arguments passed to each
The following complex types are used to pass values between the Python plugin
and collectd:
-=over 4
+=head2 Signed
+
+The Signed class is just a long. It has all its methods and behaves exactly
+like any other long object. It is used to indicate if an integer was or should
+be stored as a signed or unsigned integer object.
+
+ class Signed(long)
-=item Config
+This is a long by another name. Use it in meta data dicts
+to choose the way it is stored in the meta data.
-The Config class is an object which keeps the informations provided in the
+=head2 Unsigned
+
+The Unsigned class is just a long. It has all its methods and behaves exactly
+like any other long object. It is used to indicate if an integer was or should
+be stored as a signed or unsigned integer object.
+
+ class Unsigned(long)
+
+This is a long by another name. Use it in meta data dicts
+to choose the way it is stored in the meta data.
+
+=head2 Config
+
+The Config class is an object which keeps the information provided in the
configuration file. The sequence of children keeps one entry for each
configuration option. Each such entry is another Config instance, which
may nest further if nested blocks are used.
-class Config(object)
- | This represents a piece of collectd's config file.
- | It is passed to scripts with config callbacks (see B<register_config>)
- | and is of little use if created somewhere else.
- |
- | It has no methods beyond the bare minimum and only exists for its
- | data members
- |
- | ----------------------------------------------------------------------
- | Data descriptors defined here:
- |
- | parent
- | This represents the parent of this node. On the root node
- | of the config tree it will be None.
- |
- | key
- | This is the keyword of this item, ie the first word of any
- | given line in the config file. It will always be a string.
- |
- | values
- | This is a tuple (which might be empty) of all value, ie words
- | following the keyword in any given line in the config file.
- |
- | Every item in this tuple will be either a string or a float or a bool,
- | depending on the contents of the configuration file.
- |
- | children
- | This is a tuple of child nodes. For most nodes this will be
- | empty. If this node represents a block instead of a single line of the config
- | file it will contain all nodes in this block.
+ class Config(object)
+This represents a piece of collectd's config file. It is passed to scripts with
+config callbacks (see B<register_config>) and is of little use if created
+somewhere else.
-=item PluginData
+It has no methods beyond the bare minimum and only exists for its data members.
+
+Data descriptors defined here:
+
+=over 4
+
+=item parent
+
+This represents the parent of this node. On the root node
+of the config tree it will be None.
+
+=item key
+
+This is the keyword of this item, i.e. the first word of any given line in the
+config file. It will always be a string.
+
+=item values
+
+This is a tuple (which might be empty) of all value, i.e. words following the
+keyword in any given line in the config file.
+
+Every item in this tuple will be either a string or a float or a boolean,
+depending on the contents of the configuration file.
+
+=item children
+
+This is a tuple of child nodes. For most nodes this will be empty. If this node
+represents a block instead of a single line of the config file it will contain
+all nodes in this block.
+
+=back
+
+=head2 PluginData
This should not be used directly but it is the base class for both Values and
Notification. It is used to identify the source of a value or notification.
-class PluginData(object)
- | This is an internal class that is the base for Values
- | and Notification. It is pretty useless by itself and was therefore not
- | exported to the collectd module.
- |
- | ----------------------------------------------------------------------
- | Data descriptors defined here:
- |
- | host
- | The hostname of the host this value was read from.
- | For dispatching this can be set to an empty string which means
- | the local hostname as defined in collectd.conf.
- |
- | plugin
- | The name of the plugin that read the data. Setting this
- | member to an empty string will insert "python" upon dispatching.
- |
- | plugin_instance
- |
- | time
- | This is the Unix timestap of the time this value was read.
- | For dispatching values this can be set to 0 which means "now".
- | This means the time the value is actually dispatched, not the time
- | it was set to 0.
- |
- | type
- | The type of this value. This type has to be defined
- | in your types.db. Attempting to set it to any other value will
- | raise a TypeError exception.
- | Assigning a type is mandetory, calling dispatch without doing
- | so will raise a RuntimeError exception.
- |
- | type_instance
+ class PluginData(object)
+This is an internal class that is the base for Values and Notification. It is
+pretty useless by itself and was therefore not exported to the collectd module.
-=item Values
+Data descriptors defined here:
+
+=over 4
+
+=item host
+
+The hostname of the host this value was read from. For dispatching this can be
+set to an empty string which means the local hostname as defined in
+collectd.conf.
+
+=item plugin
+
+The name of the plugin that read the data. Setting this member to an empty
+string will insert "python" upon dispatching.
+
+=item plugin_instance
+
+Plugin instance string. May be empty.
+
+=item time
+
+This is the Unix timestamp of the time this value was read. For dispatching
+values this can be set to zero which means "now". This means the time the value
+is actually dispatched, not the time it was set to 0.
+
+=item type
+
+The type of this value. This type has to be defined in your I<types.db>.
+Attempting to set it to any other value will raise a I<TypeError> exception.
+Assigning a type is mandatory, calling dispatch without doing so will raise a
+I<RuntimeError> exception.
+
+=item type_instance
+
+Type instance string. May be empty.
+
+=back
+
+=head2 Values
A Value is an object which features a sequence of values. It is based on then
I<PluginData> type and uses its members to identify the values.
-class Values(PluginData)
- | A Values object used for dispatching values to collectd and receiving
- | values from write callbacks.
- |
- | Method resolution order:
- | Values
- | PluginData
- | object
- |
- | Methods defined here:
- |
- | dispatch(...)
- | dispatch([type][, values][, plugin_instance][, type_instance][, plugin][, host][, time][, interval]) -> None. Dispatch a value list.
- |
- | Dispatch this instance to the collectd process. The object has members
- | for each of the possible arguments for this method. For a detailed
- | explanation of these parameters see the member of the same same.
- |
- | If you do not submit a parameter the value saved in its member will be
- | submitted. If you do provide a parameter it will be used instead,
- | without altering the member.
- |
- | write(...)
- | write([destination][, type][, values][, plugin_instance][, type_instance][, plugin][, host][, time][, interval]) -> None. Dispatch a value list.
- |
- | Write this instance to a single plugin or all plugins if 'destination' is obmitted.
- | This will bypass the main collectd process and all filtering and caching.
- | Other than that it works similar to 'dispatch'. In most cases 'dispatch' should be
- | used instead of 'write'.
- |
- | ----------------------------------------------------------------------
- | Data descriptors defined here:
- |
- | interval
- | The interval is the timespan in seconds between two submits for the
- | same data source. This value has to be a positive integer, so you can't
- | submit more than one value per second. If this member is set to a
- | non-positive value, the default value as specified in the config file
- | will be used (default: 10).
- |
- | If you submit values more often than the specified interval, the average
- | will be used. If you submit less values, your graphs will have gaps.
- |
- | values
- | These are the actual values that get dispatched to collectd.
- | It has to be a sequence (a tuple or list) of numbers.
- | The size of the sequence and the type of its content depend on the type
- | member your types.db file. For more information on this read the
- | types.db man page.
- |
- | If the sequence does not have the correct size upon dispatch a
- | RuntimeError exception will be raised. If the content of the sequence
- | is not a number, a TypeError exception will be raised.
+ class Values(PluginData)
+A Values object used for dispatching values to collectd and receiving values
+from write callbacks.
-=item Notification
+Method resolution order:
+
+=over 4
+
+=item Values
+
+=item PluginData
+
+=item object
+
+=back
+
+Methods defined here:
+
+=over 4
+
+=item B<dispatch>([type][, values][, plugin_instance][, type_instance][, plugin][, host][, time][, interval]) -> None.
+
+Dispatch this instance to the collectd process. The object has members for each
+of the possible arguments for this method. For a detailed explanation of these
+parameters see the member of the same same.
+
+If you do not submit a parameter the value saved in its member will be
+submitted. If you do provide a parameter it will be used instead, without
+altering the member.
+
+=item B<write>([destination][, type][, values][, plugin_instance][, type_instance][, plugin][, host][, time][, interval]) -> None.
+
+Write this instance to a single plugin or all plugins if "destination" is
+omitted. This will bypass the main collectd process and all filtering and
+caching. Other than that it works similar to "dispatch". In most cases
+"dispatch" should be used instead of "write".
+
+=back
+
+Data descriptors defined here:
+
+=over 4
+
+=item interval
+
+The interval is the timespan in seconds between two submits for the same data
+source. This value has to be a positive integer, so you can't submit more than
+one value per second. If this member is set to a non-positive value, the
+default value as specified in the config file will be used (default: 10).
+
+If you submit values more often than the specified interval, the average will
+be used. If you submit less values, your graphs will have gaps.
+
+=item values
+
+These are the actual values that get dispatched to collectd. It has to be a
+sequence (a tuple or list) of numbers. The size of the sequence and the type of
+its content depend on the type member your I<types.db> file. For more
+information on this read the L<types.db(5)> manual page.
+
+If the sequence does not have the correct size upon dispatch a I<RuntimeError>
+exception will be raised. If the content of the sequence is not a number, a
+I<TypeError> exception will be raised.
+
+=item meta
+
+These are the meta data for this Value object.
+It has to be a dictionary of numbers, strings or bools. All keys must be
+strings. I<int> and <long> objects will be dispatched as signed integers unless
+they are between 2**63 and 2**64-1, which will result in a unsigned integer.
+You can force one of these storage classes by using the classes
+B<collectd.Signed> and B<collectd.Unsigned>. A meta object received by a write
+callback will always contain B<Signed> or B<Unsigned> objects.
+
+=back
+
+=head2 Notification
A notification is an object defining the severity and message of the status
message as well as an identification of a data instance by means of the members
-of PluginData on which it is based.
+of I<PluginData> on which it is based.
class Notification(PluginData)
- | The Notification class is a wrapper around the collectd notification.
- | It can be used to notify other plugins about bad stuff happening. It works
- | similar to Values but has a severity and a message instead of interval
- | and time.
- | Notifications can be dispatched at any time and can be received with
- | register_notification.
- |
- | Method resolution order:
- | Notification
- | PluginData
- | object
- |
- | Methods defined here:
- |
- | dispatch(...)
- | dispatch([type][, values][, plugin_instance][, type_instance][, plugin][, host][, time][, interval]) -> None. Dispatch a value list.
- |
- | Dispatch this instance to the collectd process. The object has members
- | for each of the possible arguments for this method. For a detailed
- | explanation of these parameters see the member of the same same.
- |
- | If you do not submit a parameter the value saved in its member will be
- | submitted. If you do provide a parameter it will be used instead,
- | without altering the member.
- |
- | ----------------------------------------------------------------------
- | Data descriptors defined here:
- |
- | message
- | Some kind of description what's going on and why this Notification
- | was generated.
- |
- | severity
- | The severity of this notification. Assign or compare to
- | NOTIF_FAILURE, NOTIF_WARNING or NOTIF_OKAY.
+The Notification class is a wrapper around the collectd notification.
+It can be used to notify other plugins about bad stuff happening. It works
+similar to Values but has a severity and a message instead of interval
+and time.
+Notifications can be dispatched at any time and can be received with
+register_notification.
+
+Method resolution order:
+=over 4
+
+=item Notification
+
+=item PluginData
+
+=item object
+
+=back
+
+Methods defined here:
+
+=over 4
+
+=item B<dispatch>([type][, values][, plugin_instance][, type_instance][, plugin][, host][, time][, interval]) -> None. Dispatch a value list.
+
+Dispatch this instance to the collectd process. The object has members for each
+of the possible arguments for this method. For a detailed explanation of these
+parameters see the member of the same same.
+
+If you do not submit a parameter the value saved in its member will be
+submitted. If you do provide a parameter it will be used instead, without
+altering the member.
+
+=back
+
+Data descriptors defined here:
+
+=over 4
+
+=item message
+
+Some kind of description what's going on and why this Notification was
+generated.
+
+=item severity
+
+The severity of this notification. Assign or compare to I<NOTIF_FAILURE>,
+I<NOTIF_WARNING> or I<NOTIF_OKAY>.
=back
There are eight different register functions to get callback for eight
different events. With one exception all of them are called as shown above.
+=over 4
+
+=item
+
I<callback> is a callable object that will be called every time the event is
- triggered.
+triggered.
+
+=item
+
I<data> is an optional object that will be passed back to the callback function
- every time it is called. If you obmit this parameter no object is
- passed back to your callback, not even None.
+every time it is called. If you omit this parameter no object is passed back to
+your callback, not even None.
+
+=item
+
I<name> is an optional identifier for this callback. The default name is
- B<python>.I<module>.I<name>'. I<module> and I<name> are taken from the
- B<__module__> and B<__name__> attributes of your callback function. If
- the parameter I<name> contains a B<.>' it replaces both I<module> and
- I<name>, otherwise it replaces only I<name>.
- Every callback needs a unique identifier, so if you want to register
- one function multiple time you need to specify a name here. Otherwise
- it's save to ignore this parameter
-I<identifier> is the full identifier assigned to this callback.
-
-These functions are called in the various stages of the daemon (see the
-section "WRITING YOUR OWN PLUGINS" above) and are passed the following
-arguments:
+B<python>.I<module>. I<module> is taken from the B<__module__> attribute of
+your callback function. Every callback needs a unique identifier, so if you
+want to register the same callback multiple time in the same module you need to
+specify a name here. Otherwise it's save to ignore this parameter I<identifier>
+is the full identifier assigned to this callback.
+
+=back
+
+These functions are called in the various stages of the daemon (see the section
+L<"WRITING YOUR OWN PLUGINS"> above) and are passed the following arguments:
=over 4
data type.
Note that you can not receive the whole config files this way, only B<Module>
blocks inside the Python configuration block. Additionally you will only
-receive blocks where your callback identifier matches B<python.>I<blockname>. In
-order for this to work the way the identifier is constructed is shortened to
-not have a I<name> part.
+receive blocks where your callback identifier matches B<python.>I<blockname>.
=item register_init
=item register_flush
-Like B<register_config> the identifier is shortened because it determines what
-flush requests the plugin will receive.
+Like B<register_config> is important for this callback because it determines
+what flush requests the plugin will receive.
The arguments passed are I<timeout> and I<identifier>. I<timeout> indicates
that only data older than I<timeout> seconds is to be flushed. I<identifier>
end.
If this callback throws an exception it will B<not> be logged. It will just be
-printed to sys.stderr which usually means silently ignored.
+printed to B<sys.stderr> which usually means silently ignored.
=item register_notification
=item B<unregister_*>(I<identifier>) -> None
Removes a callback or data-set from collectd's internal list of callback
-functions. Every register_* function has an unregister_* function. I<identifier>
-is either the string that was returned by the register function or a callback
-function. The identifier will be constructed in the same way as for the
-register functions.
+functions. Every I<register_*> function has an I<unregister_*> function.
+I<identifier> is either the string that was returned by the register function
+or a callback function. The identifier will be constructed in the same way as
+for the register functions.
=item B<flush>(I<plugin[, I<timeout>][, I<identifier>]) -> None
collectd.register_read(read);
collectd.register_write(write);
-See the section "CLASSES" above for a complete documentation of the data
+See the section L<"CLASSES"> above for a complete documentation of the data
types used by the read, write and match functions.
=head1 NOTES
=item
-This plugin is not compatible with python3. Trying to complie it with python3
-will fail because of the ways string, unicode and bytearray bahavior was
-changed.
-
-Not all aspects of the collectd API are accessable from python. This includes
-but is not limited to meta-data, filters and data sets.
+Not all aspects of the collectd API are accessible from python. This includes
+but is not limited to filters and data sets.
=back
=head1 AUTHOR
-The C<python plugin> has been written by Sebastian Harl
-E<lt>shE<nbsp>atE<nbsp>tokkee.orgE<gt>.
+The C<python plugin> has been written by
+Sven Trenkel E<lt>collectdE<nbsp>atE<nbsp>semidefinite.deE<gt>.
-This manpage has been written by Florian Forster
-E<lt>octoE<nbsp>atE<nbsp>verplant.orgE<gt> and Sebastian Harl
-E<lt>shE<nbsp>atE<nbsp>tokkee.orgE<gt>.
+This manpage has been written by Sven Trenkel
+E<lt>collectdE<nbsp>atE<nbsp>semidefinite.deE<gt>.
+It is based on the L<collectd-perl(5)> manual page by
+Florian Forster E<lt>octoE<nbsp>atE<nbsp>verplant.orgE<gt> and
+Sebastian Harl E<lt>shE<nbsp>atE<nbsp>tokkee.orgE<gt>.
=cut
-
projects / collectd.git / blobdiff