Horizon 源码阅读（四）—— 调用Novaclient流程

一、写在前面
这篇文章主要介绍一下Openstack（Kilo）关于horizon 调用NovaClient的一个分析。
如果转载，请保留作者信息。

邮箱地址：jpzhang.ht@gmail.com

二、novaclient目录结构
novaclient/
|---client.py --------主要提供HTTPClient类，也提供根据版本创建Client对象的函数
|---base.py --------提供基本的Manager基类
|---shell.py --------命令解析，创建相应版本的Client类对象，调用相应版本的shell.py中的函数
...
|---v2
|---client.py ---------版本Client类，拥有一系列Manager类对象，这些Manager可以调用相应的组件
|---flavors.py --------具体的Manager类，使用HTTPClient对象与对应的组件进行通信
...
|---shell.py ————提供每个Command对应的方法

三、以创建虚拟机为例分析源码
/openstack_dashboard/api/nova.py
horizon 调用APi创建虚拟机

def server_create(request, name, image, flavor, key_name, user_data,
security_groups, block_device_mapping=None,
block_device_mapping_v2=None, nics=None,
availability_zone=None, instance_count=1, admin_pass=None,
disk_config=None, config_drive=None, meta=None):
return Server(novaclient(request).servers.create(
name, image, flavor, userdata=user_data,
security_groups=security_groups,
key_name=key_name, block_device_mapping=block_device_mapping,
block_device_mapping_v2=block_device_mapping_v2,
nics=nics, availability_zone=availability_zone,
min_count=instance_count, admin_pass=admin_pass,
disk_config=disk_config, config_drive=config_drive,
meta=meta), request)

返回一个创建后的Server对象，调用novaclient(request).servers.create()传入参数,发送创建虚拟机的请求。
novaclient(request).servers.create(
name, image, flavor….), request

调用流程：
novaclient(request）-> servers -> create
1、novaclient(request）:返回一个novaclient对象。
/openstack_dashboard/api/nova.py

def novaclient(request):
# 获取是否SSL证书检查，默认是禁用
insecure = getattr(settings, 'OPENSTACK_SSL_NO_VERIFY', False)
#获取CA证书使用来验证SSL连接，默认是None
cacert = getattr(settings, 'OPENSTACK_SSL_CACERT', None)

#from novaclient.v2 import client as nova_client 返回Client类
<strong>［1］</strong>c = nova_client.Client(request.user.username,
request.user.token.id,
project_id=request.user.tenant_id,
auth_url=base.url_for(request, 'compute'),
insecure=insecure,
cacert=cacert,
http_log_debug=settings.DEBUG)
#设置Token ID 值
c.client.auth_token = request.user.token.id
#设置访问地址：例如 http://hty-nova:8774/v2/ea4d1859494c490495b027f174de307c c.client.management_url = base.url_for(request, 'compute')
return c

novaclient/v2/__init__.py
from novaclient.v2.client import Client

［1］处代码分析，返回一个Client对象

class Client(object):
"""
顶级对象访问OpenStack计算API。
Top-level object to access the OpenStack Compute API.

"""

def __init__(self, username=None, api_key=None, project_id=None,
auth_url=None, insecure=False, timeout=None,
...):

password = api_key
self.projectid = project_id
...

# extensions 扩展
self.agents = agents.AgentsManager(self)
self.dns_domains = floating_ip_dns.FloatingIPDNSDomainManager(self)
...

# Add in any extensions...在添加任何扩展
if extensions:
for extension in extensions:
if extension.manager_class:
setattr(self, extension.name,
extension.manager_class(self))
#构建HTTP客户端
self.client = client._construct_http_client(
username=username,
password=password,
...
**kwargs)
...

这个client里面有一个Client类，拥有一堆的Manager负责管理各种资源，只需引用这些Manager就可以操作资源，然后创建一系列的Manager类来负责处理资源，在这些Manager类中主要使用HTTPClient来发送请求对相应的组件进行操作，最后，将client版本能够实现的功能封装成函数，这些函数进而能够被相应的command调用。

2、novaclient(request).servers.create():
novaclient/v2/client.py
引用ServerManager操作server

class Client(object):
def __init__(self, username=None, api_key=None, project_id=None,…)
….
#负责管理servers，只需引用Manager就可以操作servers
self.servers = servers.ServerManager(self)
…

novaclient/v2/servers.py
创建虚拟机create() 函数

class ServerManager(base.BootingManagerWithFind):
resource_class = Server # 资源类,上文定义

def create(self, name, image, flavor, meta=None, files=None,
reservation_id=None, min_count=None,
max_count=None, security_groups=None, userdata=None,
key_name=None, availability_zone=None,
block_device_mapping=None, block_device_mapping_v2=None,
nics=None, scheduler_hints=None,
config_drive=None, disk_config=None, **kwargs):
"""
Create (boot) a new server.创建（启动）新的服务器。

"""
#判断虚拟机创建数量
if not min_count:
min_count = 1
if not max_count:
max_count = min_count
if min_count > max_count:
min_count = max_count

# 组拼参数
boot_args = [name, image, flavor]

boot_kwargs = dict(
meta=meta, files=files, userdata=userdata,
reservation_id=reservation_id, min_count=min_count,
max_count=max_count, security_groups=security_groups,
key_name=key_name, availability_zone=availability_zone,
scheduler_hints=scheduler_hints, config_drive=config_drive,
disk_config=disk_config, **kwargs)

#block_device_mapping：（可选扩展）的块设备映射此虚拟机的字典。
if block_device_mapping:
resource_url = "/os-volumes_boot"
boot_kwargs['block_device_mapping'] = block_device_mapping
elif block_device_mapping_v2:
resource_url = "/os-volumes_boot"
boot_kwargs['block_device_mapping_v2'] = block_device_mapping_v2
else:
resource_url = “/servers”

# nics（可选扩展）的NIC的有序列表要添加到该虚拟机，与有关连接的网络，固定的IP地址，端口等。
if nics:
boot_kwargs['nics'] = nics

response_key = “server"
#调用_boot()
return self.<strong>_boot</strong>(resource_url, response_key, *boot_args,
**boot_kwargs)

def <strong>_boot</strong>(self, resource_url, response_key, name, image, flavor,
meta=None, files=None, userdata=None,
reservation_id=None, return_raw=False, min_count=None,
max_count=None, security_groups=None, key_name=None,
availability_zone=None, block_device_mapping=None,
block_device_mapping_v2=None, nics=None, scheduler_hints=None,
config_drive=None, admin_pass=None, disk_config=None, **kwargs):
"""
Create (boot) a new server. 创建（启动）新的服务器。
"""
# 调用Restful API带的body参数
body = {"server": {
"name": name,
"imageRef": str(base.getid(image)) if image else '',
"flavorRef": str(base.getid(flavor)),
}}
if userdata:
if hasattr(userdata, 'read'):
userdata = userdata.read()

if six.PY3:
userdata = userdata.encode("utf-8")
else:
userdata = encodeutils.safe_encode(userdata)

userdata_b64 = base64.b64encode(userdata).decode('utf-8')
body["server"]["user_data"] = userdata_b64
if meta:
body["server"]["metadata"] = meta
if reservation_id:
body["server"]["reservation_id"] = reservation_id
if key_name:
body["server"]["key_name"] = key_name
if scheduler_hints:
body['os:scheduler_hints'] = scheduler_hints
if config_drive:
body["server"]["config_drive"] = config_drive
if admin_pass:
body["server"]["adminPass"] = admin_pass
if not min_count:
min_count = 1
if not max_count:
max_count = min_count
body["server"]["min_count"] = min_count
body["server"]["max_count"] = max_count

if security_groups:
body["server"]["security_groups"] = [{'name': sg}
for sg in security_groups]

# Files are a slight bit tricky. They're passed in a "personality"
# list to the POST. Each item is a dict giving a file name and the
# base64-encoded contents of the file. We want to allow passing
# either an open file *or* some contents as files here.
if files:
personality = body['server']['personality'] = []
for filepath, file_or_string in sorted(files.items(),
key=lambda x: x[0]):
if hasattr(file_or_string, 'read'):
data = file_or_string.read()
else:
data = file_or_string

if six.PY3 and isinstance(data, str):
data = data.encode('utf-8')
cont = base64.b64encode(data).decode('utf-8')
personality.append({
'path': filepath,
'contents': cont,
})

if availability_zone:
body["server"]["availability_zone"] = availability_zone

# Block device mappings are passed as a list of dictionaries
if block_device_mapping:
body['server']['block_device_mapping'] = \
self._parse_block_device_mapping(block_device_mapping)
elif block_device_mapping_v2:
body['server']['block_device_mapping_v2'] = block_device_mapping_v2

if nics is not None:
# NOTE(tr3buchet): nics can be an empty list
all_net_data = []
for nic_info in nics:
net_data = {}
# if value is empty string, do not send value in body
if nic_info.get('net-id'):
net_data['uuid'] = nic_info['net-id']
if (nic_info.get('v4-fixed-ip') and
nic_info.get('v6-fixed-ip')):
raise base.exceptions.CommandError(_(
"Only one of 'v4-fixed-ip' and 'v6-fixed-ip' may be"
" provided."))
elif nic_info.get('v4-fixed-ip'):
net_data['fixed_ip'] = nic_info['v4-fixed-ip']
elif nic_info.get('v6-fixed-ip'):
net_data['fixed_ip'] = nic_info['v6-fixed-ip']
if nic_info.get('port-id'):
net_data['port'] = nic_info['port-id']
all_net_data.append(net_data)
body['server']['networks'] = all_net_data

if disk_config is not None:
body['server']['OS-DCF:diskConfig'] = disk_config
# 调用父类基类Manager._create()方法
# ServerManager->BootingManagerWithFind->ManagerWithFind->Manager
return self.<strong>_create</strong>(resource_url, body, response_key,
return_raw=return_raw, **kwargs)

novaclient/base.py

class Manager(base.HookableMixin):
"""
Managers interact with a particular type of API (servers, flavors, images,
etc.) and provide CRUD operations for them.
"""
# 管理者与特定类型的API（servers, flavors, images,etc）进行交互，并为他们提供CRUD操作。

resource_class = None
cache_lock = threading.RLock()

def __init__(self, api):# api 即 Client对象，从<span style="font-family: Arial, Helvetica, sans-serif;">novaclient/v2/client.py:self.servers = servers.ServerManager(self)传入</span>
self.api = api

def <strong>_create</strong>(self, url, body, response_key, return_raw=False, **kwargs):
# 运行指定类型的所有挂钩。
self.run_hooks('modify_body_for_create', body, **kwargs)
# self.api 即novaclient/v2/client.py:self.servers = servers.ServerManager(self) class -> Client(object)对象;
# client: self.client HTTPClient客户端对象 novaclient/client.py->def _construct_http_client() -> class HTTPClient(object)->def post()
# 发起post请求
_resp, body = self.api.client.<strong>post</strong>(url, body=body)
if return_raw:
return body[response_key]

with self.completion_cache('human_id', self.resource_class, mode="a"):
with self.completion_cache('uuid', self.resource_class, mode="a"):
return self.resource_class(self, body[response_key])

novaclient/client.py/class HTTPClient(object)

#调用POST 发送请求

def post(self, url, **kwargs):
return self.<strong>_cs_request</strong>(url, 'POST', **kwargs)s

def <strong>_cs_request</strong>(self, url, method, **kwargs):
if not self.management_url:
self.authenticate()
if url is None:
# To get API version information, it is necessary to GET
# a nova endpoint directly without "v2/<tenant-id>".
magic_tuple = parse.urlsplit(self.management_url)
scheme, netloc, path, query, frag = magic_tuple
path = re.sub(r'v[1-9]/[a-z0-9]+$', '', path)
url = parse.urlunsplit((scheme, netloc, path, None, None))
else:
if self.service_catalog:
url = self.get_service_url(self.service_type) + url
else:
# NOTE(melwitt): The service catalog is not available
#                when bypass_url is used.
url = self.management_url + url

# Perform the request once. If we get a 401 back then it
# might be because the auth token expired, so try to
# re-authenticate and try again. If it still fails, bail.
try:
kwargs.setdefault('headers', {})['X-Auth-Token'] = self.auth_token
if self.projectid:
kwargs['headers']['X-Auth-Project-Id'] = self.projectid

resp, body = self.<strong>_time_request</strong>(url, method, **kwargs)
return resp, body
"""有可能出现没有认证的情况，需要先认证再发送请求 """
except exceptions.Unauthorized as e:
...

def <strong>_time_request</strong>(self, url, method, **kwargs):
start_time = time.time()
resp, body = self.<strong>request</strong>(url, method, **kwargs)
self.times.append(("%s %s" % (method, url),
start_time, time.time()))
return resp, body

def <strong>request</strong>(self, url, method, **kwargs):
""" 构造请求报文参数 """
kwargs.setdefault('headers', kwargs.get('headers', {}))
kwargs['headers']['User-Agent'] = self.USER_AGENT
kwargs['headers']['Accept'] = 'application/json'
if 'body' in kwargs:
kwargs['headers']['Content-Type'] = 'application/json'
kwargs['data'] = json.dumps(kwargs['body'])
del kwargs['body']
if self.timeout is not None:
kwargs.setdefault('timeout', self.timeout)
kwargs['verify'] = self.verify_cert

self.http_log_req(method, url, kwargs)

request_func = requests.request
session = self._get_session(url)
if session:
request_func = session.request

""" 这里使用了第三方的 requests 库，发起post请求"""
resp = request_func(
method,
url,
**kwargs)

self.http_log_resp(resp)

if resp.text:
# TODO(dtroyer): verify the note below in a requests context
# NOTE(alaski): Because force_exceptions_to_status_code=True
# httplib2 returns a connection refused event as a 400 response.
# To determine if it is a bad request or refused connection we need
# to check the body.  httplib2 tests check for 'Connection refused'
# or 'actively refused' in the body, so that's what we'll do.
""" 根据请求返回的结果决定是否抛出异常 """
if resp.status_code == 400:
if ('Connection refused' in resp.text or
'actively refused' in resp.text):
raise exceptions.ConnectionRefused(resp.text)
try:
body = json.loads(resp.text)
except ValueError:
body = None
else:
body = None
""" 根据请求返回的结果决定是否抛出异常 """
if resp.status_code >= 400:
raise exceptions.from_response(resp, body, url, method)
# 返回调用结果
return resp, body