[openstack-dev] [Fuel] [Plugins] Further development of plugin metadata format
vkramskikh at mirantis.com
Sun Nov 30 12:12:50 UTC 2014
2014-11-28 23:20 GMT+04:00 Dmitriy Shulyak <dshulyak at mirantis.com>:
>> - environment_config.yaml should contain exact config which will be
>> mixed into cluster_attributes. No need to implicitly generate any controls
>> like it is done now.
>> Initially i had the same thoughts and wanted to use it the way it is,
> but now i completely agree with Evgeniy that additional DSL will cause a lot
> of problems with compatibility between versions and developer experience.
As far as I understand, you want to introduce another approach to describe
UI part or plugins?
> We need to search for alternatives..
> 1. for UI i would prefer separate tab for plugins, where user will be able
> to enable/disable plugin explicitly.
Of course, we need a separate page for plugin management.
> Currently settings tab is overloaded.
> 2. on backend we need to validate plugins against certain env before
> enabling it,
> and for simple case we may expose some basic entities like network_mode.
> For case where you need complex logic - python code is far more flexible
> that new DSL.
>> - metadata.yaml should also contain "is_removable" field. This field
>> is needed to determine whether it is possible to remove installed plugin.
>> It is impossible to remove plugins in the current implementation.
>> This field should contain an expression written in our DSL which we already
>> use in a few places. The LBaaS plugin also uses it to hide the checkbox if
>> Neutron is not used, so even simple plugins like this need to utilize it.
>> This field can also be autogenerated, for more complex plugins plugin
>> writer needs to fix it manually. For example, for Ceph it could look like
>> "settings:storage.volumes_ceph.value == false and
>> settings:storage.images_ceph.value == false".
>> How checkbox will help? There is several cases of plugin removal..
It is not a checkbox, this is condition that determines whether the plugin
is removable. It allows plugin developer specify when plguin can be safely
removed from Fuel if there are some environments which were created after
the plugin had been installed.
> 1. Plugin is installed, but not enabled for any env - just remove the
> 2. Plugin is installed, enabled and cluster deployed - forget about it for
> 3. Plugin is installed and only enabled - we need to maintain state of db
> consistent after plugin is removed, it is problematic, but possible
My approach also allows to eliminate "enableness" of plugins which will
cause UX issues and issues like you described above. vCenter and Ceph also
don't have "enabled" state. vCenter has hypervisor and storage, Ceph
provides backends for Cinder and Glance which can be used simultaneously or
only one of them can be used.
> My main point that plugin is enabled/disabled explicitly by user, after
> that we can decide ourselves can it be removed or not.
>> - For every task in tasks.yaml there should be added new "condition"
>> field with an expression which determines whether the task should be run.
>> In the current implementation tasks are always run for specified roles. For
>> example, vCenter plugin can have a few tasks with conditions like
>> "settings:common.libvirt_type.value == 'vcenter'" or
>> "settings:storage.volumes_vmdk.value == true". Also, AFAIU, similar
>> approach will be used in implementation of Granular Deployment feature.
>> I had some thoughts about using DSL, it seemed to me especially helpfull
> when you need to disable part of embedded into core functionality,
> like deploying with another hypervisor, or network dirver (contrail for
> example). And DSL wont cover all cases here, this quite similar to
> metadata.yaml, simple cases can be covered by some variables in tasks (like
> group, unique, etc), but complex is easier to test and describe in python.
Could you please provide example of such conditions? vCenter and Ceph can
be turned into plugins using this approach.
Also, I'm not against python version of plugins. It could look like a
python class with exactly the same fields form YAML files, but conditions
will be written in python.
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