openstack/fuel-docs
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Nailgun extensions docs - fix Eli's comments

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Eli's comments, see here: https://review.openstack.org/#/c/295846/7/

Change-Id: I2597f7b5ea8da16ed1d3cc7070c8405920eb040f
implements: blueprint data-pipeline
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Sylwester Brzeczkowski 2016-04-07 12:04:56 +02:00
parent 8db61f1a2c
commit 218ad7defa
2 changed files with 27 additions and 13 deletions
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38
devdocs/develop/nailgun/customization/extensions.rst
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@ -5,10 +5,10 @@ __________________
Overview of extensions
======================
Nailgun extensions provide a capability to extend Fuel features.
Extensions were introduced to provide *pythonic way* for adding integrations
with external services, extending existing features, or adding new features
**without** changing the Nailgun source code.
Nailgun extensions provide a capability for Fuel Developers to extend Fuel
features. Extensions were introduced to provide *pythonic way* for adding
integrations with external services, extending existing features, or adding
new features **without** changing the Nailgun source code.
A Nailgun extension can execute its method on specific events
such as ``on_node_create`` or ``on_cluster_delete`` (more about event handlers
@ -16,6 +16,14 @@ in the `Available Events`_ section) and also to change deployment and
provisioning data just before it is sent to orchestrator by the means of
Data Pipelines classes.
.. note::
The extensions mechanism does not provide a sufficient level
of isolation. Therefore, the extension may not work after you upgrade Fuel.
On the contrary, Fuel plugins provide backward compatibility and a friendly
UI for the end user. Use plugins for all changes in the system performed
by the Fuel user.
Required properties
===================
@ -26,8 +34,8 @@ All Nailgun extensions must populate the following class variables:
extension. It should consist only of lowercase letters with "_" (underscore)
separator and digits.
* ``version`` - a string which should look like *X.Y.Z* where X is a major
version, Y is minor, and Z is bug fix update or build number.
* ``version`` - a string with version. It should follow semantic versioning:
http://semver.org/
* ``description`` - a short text which briefly describes the actions that the
extension performs.
@ -99,8 +107,8 @@ Database interaction
====================
There is a possibility to use the Nailgun database to store the data needed by
a Nailgun extension. To use it, provide alembic migration scripts which should
be placed in::
a Nailgun extension. To use it you must provide alembic migration scripts which
should be placed in::
extension_module/alembic_migrations/migrations/
@ -114,10 +122,16 @@ You can also change this directory by overriding the classmethod::
It should return an absolute path (string) to alembic migrations
directory.
.. important::
Do not use the direct db calls to Nailgun core tables in the extension
class. Use the ``nailgun.objects`` module which ensures compatibility
between the Nailgun DB and the configuration implemented in your extension.
Additionally, use a table name with an extension-specific prefix in models
classes and alembic migration scripts. We recommend that you use the
``table_prefix`` extension method to retrieve the prefix (string).
.. note::
Do not use the direct db calls to Nailgun core tables in the extension
class. Use the ``nailgun.objects`` module which ensures compatibility
between the Nailgun DB and the configuration implemented in your extension.
There **must be no** relations between extension models and core models.
Extension Data Pipelines

2
userdocs/fuel-install-guide/plugins/plugins_prerequisites.rst
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@ -14,4 +14,4 @@ following:
.. seealso::
- `Fuel plugins catalog
<http://stackalytics.com/report/driverlog?project_id=openstack%2Ffuel¬>`__
<http://stackalytics.com/report/driverlog?project_id=openstack%2Ffuel>`__