openstack/charm-interface-manila-plugin
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plugin interface for manila to backends

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This commit contains the interface code to connect between the
manila charm and a backend plugin that will provide configuration
for the manila.

Plugin charms are subordinate because they need to be on the same
unit/machine as the manila file share service.

This interface also implements a 1-many interface and so contains code
to manage that.  That code will be abstracted back to charms.openstack
at some point.

Change-Id: Ied0ad014ab7b1d4778113b0d3f2bbae08075372e
This commit is contained in:
Alex Kavanagh 2016-11-15 18:56:24 +00:00 committed by Ryan Beisner
parent 99afa9509e
commit a4f85602af
8 changed files with 747 additions and 0 deletions
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bin
.coverage
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.tox
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*.sw[nop]
*.pyc
.unit-state.db
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# Overview
This interface provides a mechanism for 'plugins' to the the Manila charm to
provide configuration sections/parts to to the Manila charm.
It is intended to be used to enable manila share backends to be configured
independently of the main charm, so that vendors/maintainers can supply their
own backend configuration charms as the project continues.
# Manila usage
This interface is used between the Manila charm (share backend role or all) to
provide the manila service user auth details to backend configuraiton charms,
and to obtain configuration information that needs to be written into 8
No explicit handler is required to consume this interface in charms
that consume this interface.
The interface provides `manila-plugin.connected` and `manila-plugin.available`
states.
## For a Manila backend subordinate charm
A Manila subordinate charm uses this interface to configure the manila
configuration files to 'plugin' its functionality. e.g. the generic backend
needs authentication information (the manila service user) so that it can
generate the configuration information for nova, neutron and cinder as part of
the backend configuration in manila.conf.
The generic charm then needs to set the configuration that the manila principal
charm will use to write the manila.conf and other files. i.e. the manila charm
will fold in the data presented into the its configuration information.
## How the conversation 'goes' between the principal (manila) and subordinate
1. Juju connects the two charms.
2. When the 'requires' side connects (hook
`{requires:manila-plugin}-relation-joined` fires), the Manila principal
charm will receive the state({relation_name}.connected).
3. When the 'provides' side connect (hook
`{provides:manila-plugin}-relation-joined` fires) the subordinate charm
will receive the state({relation_name}.connected).
4. When the Manila charm has received keystone authentication information it
will set that on the relation, and on receipt the 'provides' side will set
the `{relation_name}.available` state. This allows the providing
charm (subordinate backend) to use this information.
5. If the subordinate needs the auth info, then it should block until
`{relation_name}.available` is available.
6. The subordinate should present its configuration information on the
interface, which will be received on the 'requires' side. This will set
the `{relation_name}.available`.
7. If either side changes 'their' data (e.g. the data they set on the
interface), then the receiving side will set the `{relation_name}.changed`
state. IF the consuming charm uses the `...changed` state, it MUST remove
it as otherwise it will not 'receive' it again.
The important points are:
- the `...available` state indicates the _first_ time that the data from the
_other_ side of the interface.
- the `...changed` state indicates the _next_ and subsequent times that data
from the _other_ side has changed. This may not be important to the
subordinate, but Manila will use this to rewrite the configuration files.
- If the subordinate consumes the `...changed` state, then it must remove it
at the end of processing, so that it can 'see' it the next time it is set.
# metadata
To consume this interface in your charm or layer, add the following to
`layer.yaml`:
```yaml
includes: ['interface:manila-plugin']
```
and add a provides interface of type `manila` to your charm or layers
`metadata.yaml`:
```yaml
provides:
manila:
interface: manila-plugin
scope: container
```
Please see the example 'Manila generic backend' charm for an example of how to
author a manila backend configuration charm.
# Bugs
Please report bugs on
[Launchpad](https://bugs.launchpad.net/openstack-charms/+filebug).
For development questions please refer to the OpenStack
[Charm Guide](https://github.com/openstack/charm-guide).

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name: manila-plugin
summary: Interface for configuration plugins to charm-manila
maintainer: OpenStack Charmers <openstack-charmers@lists.ubuntu.com>
repo: https://github.com/openstack/charm-interface-manila-plugin

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# Copyright 2016 Canonical Ltd
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
import json
import charms.reactive as reactive
class ManilaPluginProvides(reactive.RelationBase):
"""This is the subordinate end of the relation. i.e. the configuration
provider to the manila plugin.
The purpose of the provides side of the interface is to provide the manila
charm with configuration information to correctly link to whatever the
plugin wants to do. e.g. for a backend, to configure manila to use the
appropriate backend.
The manila charm provides the service user manila, and other authentication
information that it can use to configure other services in the OpenStack
system.
"""
scope = reactive.scopes.GLOBAL
# These remote data fields will be automatically mapped to accessors
# with a basic documentation string provided.
auto_accessors = ['_authentication_data']
@reactive.hook('{provides:manila-plugin}-relation-joined')
def joined(self):
self.set_state('{relation_name}.connected')
self.update_status()
@reactive.hook('{provides:manila-plugin}-relation-changed')
def changed(self):
"""This hook is used to indicate that something has changed on the
interface and that interested parties should recheck the properties
exposed to see if they need to do anything.
The handler should clear the state after it has been consumed so that
the next change gets registered too.
"""
self.update_status()
@reactive.hook('{provides:manila-plugin}-relation-{broken,departed}')
def departed(self):
self.remove_state('{relation_name}.changed')
self.remove_state('{relation_name}.available')
self.remove_state('{relation_name}.connected')
def update_status(self):
"""Set the .available and .changed state if both the plugin name and
the authentication data are available.
Note that the .changed state can be used if the plugin changes the
data. Thus, a subordinate charm (e.g. generic backend) can watched
changed and then clear it using the method clear_changed() to update
configuration files as needed.
The interface will NOT set .changed without having .available at the
same time.
"""
if self._authentication_data() is not None:
self.set_state('{relation_name}.available')
self.set_state('{relation_name}.changed')
def clear_changed(self):
"""Provide a convenient method to clear the .changed relation"""
self.remove_state('{relation_name}.changed')
@property
def name(self):
"""Returns the name if it has been set"""
scope = self.conversations()[0].scope
return self.get_local('_name', default=None, scope=scope)
@name.setter
def name(self, name):
"""Set the name plugin -- this is for logs, and to distinguish between
multiple plugins.
:param name: a string indicating the name of the plugin (or None)
"""
scope = self.conversations()[0].scope
self.set_local(_name=name, scope=scope)
self.set_remote(_name=name, scope=scope)
@property
def authentication_data(self):
"""Return authentication data provided by the Manila charm, or None if
the data has not yet been set.
The authentication data is set when the Manila charm has received it
over its identity interface; thus this may return None until that data
has become available. This means that the configuration data may be
delayed until this is available.
The authentication data format is:
{
'username': <value>
'password': <value>
'project_domain_id': <value>
'project_name': <value>
'user_domain_id': <value>
'auth_uri': <value>
'auth_url': <value>
'auth_type': <value> # 'password', typically
}
:returns: data object that was passed.
"""
data = self._authentication_data()
if data is None:
return None
return json.loads(data)["data"]
@property
def configuration_data(self):
"""Get the configuration data (if it has been set yet) or None"""
scope = self.conversations()[0].scope
data = self.get_local('_configuration_data', default=None, scope=scope)
if data is None:
return
return json.loads(data)["data"]
@configuration_data.setter
def configuration_data(self, data):
"""
NOTE that the data is wrapped in a dictionary, converted to JSON and
then placed in the juju remote variable. The other 'end' unpacks this
and provides the original data to Manila charm.
If complete is False (or missing) then the configuration data is only
partially complete OR the subordinate charm is not ready yet -- e.g. it
still has to configure something.
The format of the data is:
{
"complete": <boolean>,
'<config file>': {
'<section>: (
(key, value),
(key, value),
)
}
Thus data has to be JSONable.
:param data: object that describes the plugin data to be sent.
"""
scope = self.conversations()[0].scope
self.set_local(_configuration_data=json.dumps({"data": data}),
scope=scope)
self.set_remote(_configuration_data=json.dumps({"data": data}),
scope=scope)

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# Copyright 2016 Canonical Ltd
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
import json
import charmhelpers.core.hookenv as hookenv
import charms.reactive as reactive
class ManilaPluginRequires(reactive.RelationBase):
"""The is the Manila 'end' of the relation.
The auto accessors are underscored as for some reason RelationBase only
provides these as 'calls'; i.e. they have to be used as `self._name()`.
This class therefore provides @properties `name` and `plugin_data` that can
be used directly.
This side of the interface sends the manila service user authentication
information to the plugin charm (which is a subordinate) and gets
configuration segments for the various files that the manila charm 'owns'
and, therefore, writes out.
The most important property is the 'ready' property which indicates that
the configuration data on the interface is valid and thus can be written to
the configuration files by the manila charm.
"""
scope = reactive.scopes.UNIT
# These remote data fields will be automatically mapped to accessors
# with a basic documentation string provided.
auto_accessors = ['_name', '_configuration_data']
@reactive.hook('{requires:manila-plugin}-relation-joined')
def joined(self):
"""At least one manila-plugin has joined. Thus we set the connected
state to allow the consumer to start setting authentication data.
We also update the status, as this may or may not be another plugin.
"""
self.set_state('{relation_name}.connected')
self.update_status()
@reactive.hook('{requires:manila-plugin}-relation-changed')
def changed(self):
"""Something has changed in one of the plugins, so we use update_status
to update the relation states to allow the consumer of the interface to
update any structures that it needs.
"""
self.update_status()
@reactive.hook('{requires:manila-plugin}-relation-{broken,departed}')
def departed(self):
self.update_status()
def update_status(self):
"""Set the .available and .changed state if at least one of the
conversations (with the subordinate) has a name and some configuration
data (regardless of whether it is complete).
As there can be multiple conversations, it is up to the subordinate
charm to flag up problems with its juju status as the principal charm
deals with multiple backends.
Note that the .changed state can be used if a plugin changes the data.
Thus, Manila can watch changes and then clear it using the method
clear_changed() to update configuration files as needed.
The interface will NOT set .changed without having .available at the
same time.
"""
count_available = 0
count_changed = 0
count_conversations = 0
for conversation in self.conversations():
if conversation.scope is None:
# the conversation has gone away; ignore it
continue
count_conversations += 1
# try to see if we've already had this conversation
conversation_available = self.get_local(
'_available', default=None, scope=conversation.scope)
name = self.get_remote(
'_name', default=None, scope=conversation.scope)
configuration_data = self.get_remote(
'_configuration_data',
default=None,
scope=conversation.scope)
if name is not None and configuration_data is not None:
count_available += 1
available = True
else:
available = False
# if we've changed state (or just connected)
if available != conversation_available:
self.set_local(_available=available, scope=conversation.scope)
count_changed += 1
# now update the relation states to convey what is happening.
if count_changed:
self.set_state('{relation_name}.changed')
if count_available:
self.set_state('{relation_name}.available')
else:
self.remove_state('{relation_name}.available')
if not count_conversations:
self.remove_state('{relation_name}.connected')
self.remove_state('{relation_name}.changed')
def clear_changed(self):
"""Provide a convenient method to clear the .changed relation"""
self.remove_state('{relation_name}.changed')
def set_authentication_data(self, value, name=None):
"""Set the authentication data to the plugin charm. This is to enable
the plugin to either 'talk' to OpenStack or to provide authentication
data into the configuraiton sections that it needs to set (the generic
backend needs to do this).
The authentication data format is:
{
'username': <value>
'password': <value>
'project_domain_id': <value>
'project_name': <value>
'user_domain_id': <value>
'auth_uri': <value>
'auth_url': <value>
'auth_type': <value> # 'password', typically
}
:param value: a dictionary of data to set.
:param name: OPTIONAL - target the config at a particular name only
"""
keys = {'username', 'password', 'project_domain_id', 'project_name',
'user_domain_id', 'auth_uri', 'auth_url', 'auth_type'}
passed_keys = set(value.keys())
if passed_keys.difference(keys) or keys.difference(passed_keys):
hookenv.log(
"Setting Authentication data; there may be missing or mispelt "
"keys: passed: {}".format(passed_keys),
level=hookenv.WARNING)
# need to check for each conversation whether we've sent the data, or
# whether it is different, and then set the local & remote only if that
# is the case.
for conversation in self.conversations():
if conversation.scope is None:
# the conversation has gone away; ignore it
continue
if name is not None:
conversation_name = self.get_remote('_name', default=None,
scope=conversation.scope)
if name != conversation_name:
continue
existing_auth_data = self.get_local('_authentication_data',
default=None,
scope=conversation.scope)
if existing_auth_data is not None:
# see if they are different
existing_auth = json.loads(existing_auth_data)["data"]
if (existing_auth.keys() == value.keys() and
all([v == value[k]
for k, v in existing_auth.items()])):
# the values haven't changed, so don't set them again
continue
self.set_local(_authentication_data=json.dumps({"data": value}),
scope=conversation.scope)
self.set_remote(_authentication_data=json.dumps({"data": value}),
scope=conversation.scope)
@property
def names(self):
"""Response with a list of names of backends where there is
configuration data on the interface.
:returns: list of names from the interfaces which have config data
"""
names = []
for conversation in self.conversations():
if conversation.scope is None:
# the conversation has gone away; ignore it
continue
name = self.get_remote('_name', default=None,
scope=conversation.scope)
config = self.get_remote('_configuration_data', default=None,
scope=conversation.scope)
if name and config:
names.append(name)
return names
def get_configuration_data(self, name=None):
"""Return the configuration_data from the plugin if it is available.
The format of the data returned is:
{
'<config file>': {
'<section>: (
(key, value),
(key, value),
"or string",
)
}
if 'name' is provided, then only the configuration data for that name
is returned, otherwise all of the configuration data for all
conversations is returned as an amalgamated dict.
:param name: OPTIONAL: specify the name of the interface (_name)
:returns: data object that was passed.
"""
result = {}
for conversation in self.conversations():
if conversation.scope is None:
# the conversation has gone away; ignore it
continue
if name:
_name = self.get_remote('_name', default=None,
scope=conversation.scope)
if _name != name:
continue
config = self.get_remote('_configuration_data', default=None,
scope=conversation.scope)
if config:
result.update(json.loads(config)["data"])
return result

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flake8>=2.2.4,<=2.4.1
os-testr>=0.4.1

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[tox]
envlist = pep8,py34,py35
skipsdist = True
skip_missing_interpreters = True
[testenv]
setenv = VIRTUAL_ENV={envdir}
PYTHONHASHSEED=0
install_command =
pip install --allow-unverified python-apt {opts} {packages}
commands = ostestr {posargs}
[testenv:py34]
basepython = python3.4
deps = -r{toxinidir}/test-requirements.txt
# TODO: Need to write unit tests then remove the following command.
commands = /bin/true
[testenv:py35]
basepython = python3.5
deps = -r{toxinidir}/test-requirements.txt
# TODO: Need to write unit tests then remove the following command.
commands = /bin/true
[testenv:pep8]
basepython = python2.7
deps = -r{toxinidir}/test-requirements.txt
commands = flake8 {posargs}
[testenv:venv]
commands = {posargs}
[flake8]
ignore = E402,E226