openstack-nova源码分析(八）aggregates主机组管理 metadata
aggregate 主机管理管理
可以向主机中添加，或者移除一个主机，也可以管理metadata
一. URL 及命令行：
/os-aggregates/{aggregate_id}/action
命令行：
[root@nova ~]# nova help | grep agg
aggregate-add-host Add the host to the specified aggregate.
aggregate-remove-host Remove the specified host from the specified aggregate.
aggregate-set-metadata Update the metadata associated with the aggregate.
二. 源码分析：
aggregate 主机管理功能也是定义在AggregateController 中：
class AggregateController(wsgi.Controller):
- 添加主机操作：
@wsgi.action('add_host')
@validation.schema(aggregates.add_host)
def _add_host(self, req, id, body):
"""Adds a host to the specified aggregate."""
host = body['add_host']['host']
context = _get_context(req)
context.can(aggr_policies.POLICY_ROOT % 'add_host')
try:
aggregate = self.api.add_host_to_aggregate(context, id, host)
except (exception.AggregateNotFound,
exception.ComputeHostNotFound) as e:
raise exc.HTTPNotFound(explanation=e.format_message())
except (exception.AggregateHostExists,
exception.InvalidAggregateAction) as e:
raise exc.HTTPConflict(explanation=e.format_message())
return self._marshall_aggregate(req, aggregate)
调用add_host_to_aggregate
定义如下：
def add_host_to_aggregate(self, context, aggregate_id, host_name):
"""Adds the host to an aggregate."""
aggregate_payload = {'aggregate_id': aggregate_id,
'host_name': host_name}
compute_utils.notify_about_aggregate_update(context,
"addhost.start",
aggregate_payload)
# validates the host; ComputeHostNotFound is raised if invalid
objects.Service.get_by_compute_host(context, host_name)
aggregate = objects.Aggregate.get_by_id(context, aggregate_id)
self.is_safe_to_update_az(context, aggregate.metadata,
hosts=[host_name], aggregate=aggregate)
aggregate.add_host(host_name)
self.scheduler_client.update_aggregates(context, [aggregate])
self._update_az_cache_for_host(context, host_name, aggregate.metadata)
# NOTE(jogo): Send message to host to support resource pools
self.compute_rpcapi.add_aggregate_host(context,
aggregate=aggregate, host_param=host_name, host=host_name)
aggregate_payload.update({'name': aggregate.name})
compute_utils.notify_about_aggregate_update(context,
"addhost.end",
aggregate_payload)
return aggregate
传入aggregate_id, host_name两个参数
notify_about_aggregate_update 写入日志
get_by_compute_host 获取主机信息，用于检查主机是否存在
Aggregate.get_by_id 获取主机组信息
aggregate.add_host(host_name)将主机添加到主机组中
scheduler_client.update_aggregates 刷新调度
_update_az_cache_for_host 刷新az信息
aggregate.add_host(host_name)源码如下：
@base.remotable
def add_host(self, host):
if self.in_api:
_host_add_to_db(self._context, self.id, host)
else:
db.aggregate_host_add(self._context, self.id, host)
if self.hosts is None:
self.hosts = []
self.hosts.append(host)
self.obj_reset_changes(fields=['hosts'])
最终使用api_models.AggregateHost() update 将主机信息添加到aggregate_hosts中
- remove host 删除主机
跟add host类似，这里只做简单分析:
@wsgi.action('remove_host')
@validation.schema(aggregates.remove_host)
def _remove_host(self, req, id, body):
"""Removes a host from the specified aggregate."""
host = body['remove_host']['host']
context = _get_context(req)
context.can(aggr_policies.POLICY_ROOT % 'remove_host')
try:
aggregate = self.api.remove_host_from_aggregate(context, id, host)
except (exception.AggregateNotFound, exception.AggregateHostNotFound,
exception.ComputeHostNotFound):
msg = _('Cannot remove host %(host)s in aggregate %(id)s') % {
'host': host, 'id': id}
raise exc.HTTPNotFound(explanation=msg)
except exception.InvalidAggregateAction:
msg = _('Cannot remove host %(host)s in aggregate %(id)s') % {
'host': host, 'id': id}
raise exc.HTTPConflict(explanation=msg)
return self._marshall_aggregate(req, aggregate)
实际调用remove_host_from_aggregate 移除主机
remove_host_from_aggregate步骤：
notify_about_aggregate_update写入日志
get_by_compute_host校验主机
Aggregate.get_by_id获取主机组
aggregate.delete_host(host_name)移除主机
刷新scheduler_client 调度，
刷新az
aggregate.delete_hos 源码：
@base.remotable
def delete_host(self, host):
if self.in_api:
_host_delete_from_db(self._context, self.id, host)
else:
db.aggregate_host_delete(self._context, self.id, host)
self.hosts.remove(host)
self.obj_reset_changes(fields=['hosts'])
这里实际是调用api_models.AggregateHost的delete方法进行删除
- metadata管理：
由于只有一个接口，并且只定义在一个动作中，因此metadata的管理，创建更新等操作都在一起，所以依据传入的数据为最终的数据，缺少的数据，则认为删除
源码如下：
@wsgi.action('set_metadata')
@validation.schema(aggregates.set_metadata)
def _set_metadata(self, req, id, body):
"""Replaces the aggregate's existing metadata with new metadata."""
context = _get_context(req)
context.can(aggr_policies.POLICY_ROOT % 'set_metadata')
metadata = body["set_metadata"]["metadata"]
try:
aggregate = self.api.update_aggregate_metadata(context,
id, metadata)
except exception.AggregateNotFound as e:
raise exc.HTTPNotFound(explanation=e.format_message())
except exception.InvalidAggregateAction as e:
raise exc.HTTPBadRequest(explanation=e.format_message())
return self._marshall_aggregate(req, aggregate)
实际调用： update_aggregate_metadata
源码：
def update_aggregate_metadata(self, context, aggregate_id, metadata):
"""Updates the aggregate metadata."""
aggregate = objects.Aggregate.get_by_id(context, aggregate_id)
self.is_safe_to_update_az(context, metadata, aggregate=aggregate,
action_name=AGGREGATE_ACTION_UPDATE_META)
aggregate.update_metadata(metadata)
self.scheduler_client.update_aggregates(context, [aggregate])
# If updated metadata include availability_zones, then the cache
# which stored availability_zones and host need to be reset
if metadata and metadata.get('availability_zone'):
availability_zones.reset_cache()
aggregate.updated_at = timeutils.utcnow()
return aggregate
更新az信息
更新metadata
更新调度信息
刷新可用区cache
aggregate.update_metadata(metadata)
源码：
def update_metadata(self, updates):
if self.in_api:
metadata_delete = _metadata_delete_from_db
metadata_add = _metadata_add_to_db
else:
metadata_delete = db.aggregate_metadata_delete
metadata_add = db.aggregate_metadata_add
payload = {'aggregate_id': self.id,
'meta_data': updates}
compute_utils.notify_about_aggregate_update(self._context,
"updatemetadata.start",
payload)
to_add = {}
for key, value in updates.items():
if value is None:
try:
metadata_delete(self._context, self.id, key)
except exception.AggregateMetadataNotFound:
pass
try:
self.metadata.pop(key)
except KeyError:
pass
else:
to_add[key] = value
self.metadata[key] = value
metadata_add(self._context, self.id, to_add)
compute_utils.notify_about_aggregate_update(self._context,
"updatemetadata.end",
payload)
self.obj_reset_changes(fields=['metadata'])
步骤：
notify_about_aggregate_update 写入日志
如果value值为空，则默认删除
metadata_add检查需要更新的值，以及需要新增的
metadata_add(self._context, self.id, to_add)
校验更新或新增， 部分源码如下：
already_existing_keys = set()
if all_keys:
query = query.filter(
api_models.AggregateMetadata.key.in_(all_keys))
for meta_ref in query.all():
key = meta_ref.key
meta_ref.update({"value": metadata[key]})
already_existing_keys.add(key)
new_entries = []
for key, value in metadata.items():
if key in already_existing_keys:
continue
new_entries.append({"key": key,
"value": value,
"aggregate_id": aggregate_id})
if new_entries:
context.session.execute(
api_models.AggregateMetadata.__table__.insert(),
new_entries)