nova创建虚拟机的过程是怎样的

这篇文章给大家介绍nova创建虚拟机的过程是怎样的，内容非常详细，感兴趣的小伙伴们可以参考借鉴，希望对大家能有所帮助。

1. 初衷

时常被问及"nova创建虚拟机的过程"，虽然大致是知道里面的过程的，但在某些场合之下，说"大致"知道往往决定了一场对话的无疾而终。要把这详细的内容给完整地说出来，有逻辑地说出来，还是需要细细斟酌一番的，那种"大致"的说辞就显得苍白了。毕竟作为从业者，详细地，深入地了解内部的整个过程应该是必须的基本功，这算是初衷吧。

2. 由一条命令引起的风波

nova --debug boot ubuntu_test --flavor 2 \ --image cde1d850-65bb-48f6-8ee9-b990c7ccf158 \ --num-instance 1 \--nic net-id=cfa25cef-96c3-46f1-8522-d9518eb5a451

这是一条创建虚拟机（实例）的命令，在命令中指定了新实例的名称：ubuntu_test，云主机类型：2，镜像：cde1d850-65bb-48f6-8ee9-b990c7ccf158，数量：1台，指定网络：cfa25cef-96c3-46f1-8522-d9518eb5a451。

这里要说明一下镜像和网络：

命令中的镜像网络通过这两个命令查询而来。

正如所看到的，命令中加了--debug参数，这可以让我们清楚看到在执行这个命令的过程中做了哪些具体操作。

下图就是我们执行创建实例后的过程

这里信息有点多啊，因此只好截了部分的图。详细信息整理后放在下面。并逐一分析。

3. debug输出的主要的请求

这里主要说明下面最重要的四条

3.1. 向keystone取得token

REQ: curl \ -i 'http://ubuntu80:35357/v2.0/tokens' -X POST -H "Accept: application/json" \ -H "Content-Type: application/json" -H "User-Agent: python-novaclient"      \ -d '{"auth": {"tenantName": "admin", "passwordCredentials": {"username": "admin", "password": "{SHA1}5705cc2e5fda0ab7529d5093c5e389fffe45d615"}}}'

3.2. 通过nova-api验证镜像

REQ:  curl  -i 'http://ubuntu80:8774/v2/0e962df9db3f4469b3d9bfbc5ffdaf7e/images/cde1d850-65bb-48f6-8ee9-b990c7ccf158' \ -X GET                        \ -H "Accept: application/json"  \ -H "User-Agent: python-novaclient" \ -H "X-Auth-Project-Id: admin"      \-H "X-Auth-Token: {SHA1}e87219521f61238b143fbb323b962930380ce022"

3.3. 通过nova-api验证云主机类型

REQ:  curl  -i 'http://ubuntu80:8774/v2/0e962df9db3f4469b3d9bfbc5ffdaf7e/flavors/2' \ -X GET -H "Accept: application/json" -H "User-Agent: python-novaclient" \ -H "X-Auth-Project-Id: admin" \-H "X-Auth-Token: {SHA1}e87219521f61238b143fbb323b962930380ce022"

3.4. 创建实例

REQ:  curl  -i 'http://ubuntu80:8774/v2/0e962df9db3f4469b3d9bfbc5ffdaf7e/servers' \ -X POST -H "Accept: application/json" \ -H "Content-Type: application/json"   \ -H "User-Agent: python-novaclient"    \ -H "X-Auth-Project-Id: admin"         \ -H "X-Auth-Token: {SHA1}e87219521f61238b143fbb323b962930380ce022" \-d '{"server": {"name": "ubuntu_test", "imageRef": "cde1d850-65bb-48f6-8ee9-b990c7ccf158", "flavorRef": "2", "max_count": 1, "min_count": 1, "networks": [{"uuid": "cfa25cef-96c3-46f1-8522-d9518eb5a451"}]}}'

4. 从如何取得token说起

我们都知道35357是keystone的端口，问我为啥知道是keystone，好吧，我是通过端口查到的。

恩，是的，就是keystone，我们回到我们的主题，这里向keystone发送请求的时候，组织了这样的一个数据

{    "auth": {        "tenantName": "admin",         "passwordCredentials": {            "username": "admin",             "password": "{SHA1}5705cc2e5fda0ab7529d5093c5e389fffe45d615"        }    }}

把这个数据发给keystone，目的是为了获取一个token，就是一个钥匙，有了它，我们后面的操作就可以凭借这个钥匙畅通无阻了。那keystone是怎么处理的呢。

找到keystone的源码

看到token了吧，嗯嗯，就在那里面

nano token/controllers.py

找到Auth类的authenticate方法

是不是跟上面给keystone的参数类似。这个方法一切顺利的话，在最后它会返回一个token（钥匙）。

keystone回复的是什么呢。

REQ: curl \ -i 'http://ubuntu80:35357/v2.0/tokens'  \  -X POST -H "Accept: application/json"  \ -H "Content-Type: application/json"     \ -H "User-Agent: python-novaclient"      \-d '{"auth": {"tenantName": "admin", "passwordCredentials": {"username": "admin", "password": "{SHA1}5705cc2e5fda0ab7529d5093c5e389fffe45d615"}}}'INFO (connectionpool:259) Starting new HTTP connection (1): ubuntu80DEBUG (connectionpool:390) Setting read timeout to 600.0DEBUG (connectionpool:430) "POST /v2.0/tokens HTTP/1.1" 200 1744RESP: [200] {'date': 'Mon, 18 Jan 2016 01:58:37 GMT', 'vary': 'X-Auth-Token', 'content-length': '1744', 'content-type': 'application/json', 'x-distribution': 'Ubuntu'}RESP BODY: {"access": {"token": {"issued_at": "2016-01-18T01:58:37.093849", "expires": "2016-01-18T02:58:37Z", "id": "{SHA1}e87219521f61238b143fbb323b962930380ce022", "tenant": {"enabled": true, "description": "Admin Tenant", "name": "admin", "id": "0e962df9db3f4469b3d9bfbc5ffdaf7e"}, "audit_ids": ["RugmwI0_R3ysmpJ3zF8k4Q"]}, "serviceCatalog": [{"endpoints_links": [], "endpoints": [{"adminURL": "http://ubuntu80:9292", "region": "regionOne", "publicURL": "http://ubuntu80:9292", "internalURL": "http://ubuntu80:9292", "id": "4794a2d722ab4f6bbda00d779c1410d1"}], "type": "image", "name": "glance"}, {"endpoints_links": [], "endpoints": [{"adminURL": "http://ubuntu80:8774/v2/0e962df9db3f4469b3d9bfbc5ffdaf7e", "region": "regionOne", "publicURL": "http://ubuntu80:8774/v2/0e962df9db3f4469b3d9bfbc5ffdaf7e", "internalURL": "http://ubuntu80:8774/v2/0e962df9db3f4469b3d9bfbc5ffdaf7e", "id": "a8ccc19100934fc1ae7c899dc5e17bdd"}], "type": "compute", "name": "nova"}, {"endpoints_links": [], "endpoints": [{"adminURL": "http://ubuntu80:9696", "region": "regionOne", "publicURL": "http://ubuntu80:9696", "internalURL": "http://ubuntu80:9696", "id": "656371fd3163415c95ff2fc0facbe5e1"}], "type": "network", "name": "neutron"}, {"endpoints_links": [], "endpoints": [{"adminURL": "http://ubuntu80:35357/v2.0", "region": "regionOne", "publicURL": "http://ubuntu80:5000/v2.0", "internalURL": "http://ubuntu80:5000/v2.0", "id": "4f1d53f12dc6485cb5816c83f68b7053"}], "type": "identity", "name": "keystone"}], "user": {"username": "admin", "roles_links": [], "id": "96a7c834b3f8485c87d79df7b6480c92", "roles": [{"name": "_member_"}, {"name": "admin"}], "name": "admin"}, "metadata": {"is_admin": 0, "roles": ["9fe2ff9ee4384b1894a90878d3e92bab", "fc2574382dd74936b1bc85cc2110c3c2"]}}}

太乱了，整理一下，把回复的json抽出来

{  "access": {    "token": {      "issued_at": "2016-01-18T01:58:37.093849",       "expires": "2016-01-18T02:58:37Z",       "id": "{SHA1}e87219521f61238b143fbb323b962930380ce022",       "tenant": {        "enabled": true,         "description": "Admin Tenant",         "name": "admin",         "id": "0e962df9db3f4469b3d9bfbc5ffdaf7e"      },       "audit_ids": [        "RugmwI0_R3ysmpJ3zF8k4Q"      ]    },     "serviceCatalog": [      {        "endpoints_links": [ ],         "endpoints": [          {            "adminURL": "http://ubuntu80:9292",             "region": "regionOne",             "publicURL": "http://ubuntu80:9292",             "internalURL": "http://ubuntu80:9292",             "id": "4794a2d722ab4f6bbda00d779c1410d1"          }        ],         "type": "image",         "name": "glance"      },       {        "endpoints_links": [ ],         "endpoints": [          {            "adminURL": "http://ubuntu80:8774/v2/0e962df9db3f4469b3d9bfbc5ffdaf7e",             "region": "regionOne",             "publicURL": "http://ubuntu80:8774/v2/0e962df9db3f4469b3d9bfbc5ffdaf7e",             "internalURL": "http://ubuntu80:8774/v2/0e962df9db3f4469b3d9bfbc5ffdaf7e",             "id": "a8ccc19100934fc1ae7c899dc5e17bdd"          }        ],         "type": "compute",         "name": "nova"      },       {        "endpoints_links": [ ],         "endpoints": [          {            "adminURL": "http://ubuntu80:9696",             "region": "regionOne",             "publicURL": "http://ubuntu80:9696",             "internalURL": "http://ubuntu80:9696",             "id": "656371fd3163415c95ff2fc0facbe5e1"          }        ],         "type": "network",         "name": "neutron"      },       {        "endpoints_links": [ ],         "endpoints": [          {            "adminURL": "http://ubuntu80:35357/v2.0",             "region": "regionOne",             "publicURL": "http://ubuntu80:5000/v2.0",             "internalURL": "http://ubuntu80:5000/v2.0",             "id": "4f1d53f12dc6485cb5816c83f68b7053"          }        ],         "type": "identity",         "name": "keystone"      }    ],     "user": {      "username": "admin",       "roles_links": [ ],       "id": "96a7c834b3f8485c87d79df7b6480c92",       "roles": [        {          "name": "_member_"        },         {          "name": "admin"        }      ],       "name": "admin"    },     "metadata": {      "is_admin": 0,       "roles": [        "9fe2ff9ee4384b1894a90878d3e92bab",         "fc2574382dd74936b1bc85cc2110c3c2"      ]    }  }}

看到了token中的id（{SHA1}e87219521f61238b143fbb323b962930380ce022）。后面的操作都是要带上它。

5. 验证镜像和云主机类型

在第3节中可以看到这两条验证的请求，分别是验证镜像和云主机类型

3.2. 通过nova-api验证镜像

REQ:  curl \-i 'http://ubuntu80:8774/v2/0e962df9db3f4469b3d9bfbc5ffdaf7e/images/cde1d850-65bb-48f6-8ee9-b990c7ccf158' \-X GET -H "Accept: application/json" \-H "User-Agent: python-novaclient"   \-H "X-Auth-Project-Id: admin"        \-H "X-Auth-Token: {SHA1}e87219521f61238b143fbb323b962930380ce022"

3.3. 通过nova-api验证云主机类型

REQ:  curl \-i 'http://ubuntu80:8774/v2/0e962df9db3f4469b3d9bfbc5ffdaf7e/flavors/2' \-X GET \-H "Accept: application/json"      \-H "User-Agent: python-novaclient" \-H "X-Auth-Project-Id: admin"      \-H "X-Auth-Token: {SHA1}e87219521f61238b143fbb323b962930380ce022"

这两条请求，是类似的，它们的代码位于nova.api.openstack.compute中的images.py和flavors.py中的Controller。

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