以操作记录为例子，介绍一下如何扩展nova-api组

[openstack2012]

得益于OpenStack的良好架构，对OpenStack进行扩展非常方便，每个模块都留出了各种接口和扩展点，能够让用户扩展自定义功能。下面以操作记录为例子，介绍一下如何扩展nova-api组件。

需求：

用户的一些重要操作必须记录下来，方便进行事后查询，比如instance的创建、销毁，比如公网IP的申请、分配等等。

实现：

因为所有的这些操作都是通过调用nova-api进行，我们要对nova-api进行扩展，记录相关的请求。nova-api是基于Python Paste来构建的，只需要在配置文件里面进行修改(nova-api-paste.ini)，在pipeline上添加一个名为audit的filter：

Text代码

[pipeline:openstackapi11]
pipeline = faultwrap authtoken keystonecontext ratelimit audit extensions osapiapp11

[filter:audit]
paste.filter_factory = nova.api.openstack.audit:AuditMiddleware.factory

[pipeline:openstackapi11]
pipeline = faultwrap authtoken keystonecontext ratelimit audit extensions osapiapp11

[filter:audit]
paste.filter_factory = nova.api.openstack.audit:AuditMiddleware.factory


然后我们写一个Middleware:

Python代码

import time

from nova import log as logging
from nova import wsgi as base_wsgi
from nova.api.openstack import wsgi

LOG = logging.getLogger('nova.api.audit')

class AuditMiddleware(base_wsgi.Middleware):
"""store POST/PUT/DELETE api request for audit."""
def __init__(self, application, audit_methods='POST,PUT,DELETE'):
base_wsgi.Middleware.__init__(self, application)
self._audit_methods = audit_methods.split(",")

def process_request(self, req):
self._need_audit = req.method in self._audit_methods
if self._need_audit:
self._request = req
self._requested_at = time.time()

def process_response(self, response):
if self._need_audit and response.status_int >= 200 and response.status_int < 300:
self._store_log(response)
return response

def _store_log(self, response):
req = self._request
LOG.info("tenant: %s, user: %s, %s: %s, at: %s",
req.headers.get('X-Tenant', 'admin'),
req.headers.get('X-User', 'admin'),
req.method,
req.path_info,
self._requested_at)

import time

from nova import log as logging
from nova import wsgi as base_wsgi
from nova.api.openstack import wsgi

LOG = logging.getLogger('nova.api.audit')

class AuditMiddleware(base_wsgi.Middleware):
"""store POST/PUT/DELETE api request for audit."""
def __init__(self, application, audit_methods='POST,PUT,DELETE'):
base_wsgi.Middleware.__init__(self, application)
self._audit_methods = audit_methods.split(",")

def process_request(self, req):
self._need_audit = req.method in self._audit_methods
if self._need_audit:
self._request = req
self._requested_at = time.time()

def process_response(self, response):
if self._need_audit and response.status_int >= 200 and response.status_int < 300:
self._store_log(response)
return response

def _store_log(self, response):
req = self._request
LOG.info("tenant: %s, user: %s, %s: %s, at: %s",
req.headers.get('X-Tenant', 'admin'),
req.headers.get('X-User', 'admin'),
req.method,
req.path_info,
self._requested_at)

重启一下nova-api进程，然后在dashboard上做一些操作，我们就能在日志文件里面看到如下的信息：

Text代码

tenant: 1, user: admin, POST: /1/os-security-group-rules, at: 1326352441.16
tenant: 1, user: admin, DELETE: /1/servers/32, at: 1326353021.58

tenant: 1, user: admin, POST: /1/os-security-group-rules, at: 1326352441.16
tenant: 1, user: admin, DELETE: /1/servers/32, at: 1326353021.58

这里默认记录所有的非GET请求，如果不想将PUT请求记录（PUT对应更新），在配置文件里面更改一下：

Text代码

[filter:audit]
audit_methods=POST,DELETE

[filter:audit]
audit_methods=POST,DELETE

更进一步，可以将_store_log改造一下，将数据保存到数据库，我们可以在配置文件里面添加数据库的连接信息等，然后利用API Extension来写一个扩展API，提供查询租户audit log的api功能。

原文链接：http://openstack.csdn.net/community/content.html?arcid=2808237

[wdvill]

原文链接 404了

[wdvill]

代理不工整难看啊，能否整理下