本文主要是介绍Horizon 源码阅读（四）—— 调用Novaclient流程，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！
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Nonecacert = 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/ea4d1859494c490495b027f174de307cc.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_keyself.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serversself.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 = 1if not max_count:max_count = min_countif 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_mappingelif block_device_mapping_v2:resource_url = "/os-volumes_boot"boot_kwargs['block_device_mapping_v2'] = block_device_mapping_v2else: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'] = nicsresponse_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_b64if meta:body["server"]["metadata"] = metaif reservation_id:body["server"]["reservation_id"] = reservation_idif key_name:body["server"]["key_name"] = key_nameif scheduler_hints:body['os:scheduler_hints'] = scheduler_hintsif config_drive:body["server"]["config_drive"] = config_driveif admin_pass:body["server"]["adminPass"] = admin_passif not min_count:min_count = 1if not max_count:max_count = min_countbody["server"]["min_count"] = min_countbody["server"]["max_count"] = max_countif 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_stringif 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 dictionariesif 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_v2if nics is not None:# NOTE(tr3buchet): nics can be an empty listall_net_data = []for nic_info in nics:net_data = {}# if value is empty string, do not send value in bodyif nic_info.get('net-id'):net_data['uuid'] = nic_info['net-id']if (nic_info.get('v4-fixed-ip') andnic_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_dataif 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->Managerreturn 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 = Nonecache_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 = apidef <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)sdef <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_tuplepath = 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) + urlelse:# 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_tokenif self.projectid:kwargs['headers']['X-Auth-Project-Id'] = self.projectidresp, 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, bodydef <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_AGENTkwargs['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_certself.http_log_req(method, url, kwargs)request_func = requests.requestsession = 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 = Noneelse: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这篇关于Horizon 源码阅读（四）—— 调用Novaclient流程的文章就介绍到这儿，希望我们推荐的文章对编程师们有所帮助！
