云计算openstack——虚拟机获取不到ip（13）

一、现象描述：

openstack平台中创建虚拟机后，虚拟机在web页面中显示获取到了ip，但是打开虚拟机控制台后查看网络状态，虚拟机没有ip地址，下图为故障截图：

二、分析思路：

（1）查看neutron服务状态，确保dchp服务正常运行

root@controller22::~#neutron agent-list
neutron CLI is deprecated and will be removed in the future. Use openstack CLI instead.
+--------------------------------------+--------------------+------------+-------------------+-------+----------------+---------------------------+
| id                                   | agent_type         | host       | availability_zone | alive | admin_state_up | binary                    |
+--------------------------------------+--------------------+------------+-------------------+-------+----------------+---------------------------+
| 3812cb30---bd75-9634687937f6 | DHCP agent         | controller | nova              | :-)   | True           | neutron-dhcp-agent        |
| 51a30db0--42de-b5d8-6b04e2a13baf | Open vSwitch agent | storage    |                   | :-)   | True           | neutron-openvswitch-agent |
| 63416b42-376b--b89d-12694faa2bf9 | L3 agent           | controller | nova              | :-)   | True           | neutron-l3-agent          |
| 7ce3b592-240f--bf09-9a7ecbfa7d3c | Open vSwitch agent | controller |                   | :-)   | True           | neutron-openvswitch-agent |
| 851ccdd9-ff14-4e8f-971c-9343787ef056 | Open vSwitch agent | compute    |                   | :-)   | True           | neutron-openvswitch-agent |
| 8c458dca-a306--a851-1c47a19ab3c1 | Metadata agent     | controller |                   | :-)   | True           | neutron-metadata-agent    |
+--------------------------------------+--------------------+------------+-------------------+-------+----------------+---------------------------+
root@controller22::~#

（2）查看dnsmsp进程是否正常

root@controller22::/var/log/neutron#ps aux | grep dnsmasq
nobody     0.0  0.0     ?        S    :   : dnsmasq --no-hosts --no-resolv --strict-order --except-interface=lo --pid-file=/var/lib/neutron/dhcp/1a426ffe-2bf0--96a5-74402004a17b/pid --dhcp-hostsfile=/var/lib/neutron/dhcp/1a426ffe-2bf0--96a5-74402004a17b/host --addn-hosts=/var/lib/neutron/dhcp/1a426ffe-2bf0--96a5-74402004a17b/addn_hosts --dhcp-optsfile=/var/lib/neutron/dhcp/1a426ffe-2bf0--96a5-74402004a17b/opts --dhcp-leasefile=/var/lib/neutron/dhcp/1a426ffe-2bf0--96a5-74402004a17b/leases --dhcp-match=set:ipxe, --bind-interfaces --interface=tap2c7d9cb9- --dhcp-range=set:tag0,172.16.0.0,static,86400s --dhcp-option-force=option:mtu, --dhcp-lease-max= --conf-file= --domain=openstacklocal
root       0.0  0.0     pts/    R+   :   : grep --color=auto dnsmasq
root@controller22::/var/log/neutron#

(3)检查ovs网桥中的 br-int 集成网桥是否有 tap设备 连接到了dchp-agent 的 namesapce上

root@controller22::~#ovs-vsctl show
552eea67--410a-b683-644af569c52d
    Manager "ptcp:6640:127.0.0.1"
        is_connected: true
    Bridge br-ex
        Port "eth2"
            Interface "eth2"
        Port br-ex
            Interface br-ex
                type: internal
        Port "qg-91819abf-e1"
            Interface "qg-91819abf-e1"
                type: internal
    Bridge br-int
        Controller "tcp:127.0.0.1:6633"
            is_connected: true
        fail_mode: secure
        Port "tap2c7d9cb9-96"
            tag:
            Interface "tap2c7d9cb9-96"
                type: internal
        Port br-int
            Interface br-int
                type: internal
        Port patch-tun
            Interface patch-tun
                type: patch
                options: {peer=patch-int}
        Port "qr-4056447b-ea"
            tag:
            Interface "qr-4056447b-ea"
                type: internal
    Bridge br-tun
        Controller "tcp:127.0.0.1:6633"
            is_connected: true
        fail_mode: secure
        Port "vxlan-c0a8fe97"
            Interface "vxlan-c0a8fe97"
                type: vxlan
                options: {df_default="true", in_key=flow, local_ip="192.168.254.150", out_key=flow, remote_ip="192.168.254.151"}
        Port patch-int
            Interface patch-int
                type: patch
                options: {peer=patch-tun}
        Port br-tun
            Interface br-tun
                type: internal
    ovs_version: "2.9.0"
root@controller22::~#i

在dhcp命名空间中找到对应网络的 namespace 中找到 br-int 网桥上对应的 tap 设备，然后查看 ip 配置：

root@controller22::/var/log/neutron#ip netns show
qrouter-3028515a-106a-4d77-b2bb-edd34ddbc7c7 (id: )
qdhcp-1a426ffe-2bf0--96a5-74402004a17b (id: )
root@controller22::/var/log/neutron#
root@controller22::/var/log/neutron#
root@controller22::/var/log/neutron#ip netns exec qdhcp-1a426ffe-2bf0--96a5-74402004a17b ip a
: lo: <LOOPBACK,UP,LOWER_UP> mtu  qdisc noqueue state UNKNOWN group default qlen
    link/loopback ::::: brd :::::
    inet 127.0.0.1/ scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::/ scope host
       valid_lft forever preferred_lft forever
: tap2c7d9cb9-: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu  qdisc noqueue state UNKNOWN group default qlen
    link/ether fa::3e::: brd ff:ff:ff:ff:ff:ff
    inet 172.16.199.10/ brd 172.16.255.255 scope global tap2c7d9cb9-
       valid_lft forever preferred_lft forever
    inet 169.254.169.254/ brd 169.254.255.255 scope global tap2c7d9cb9-
       valid_lft forever preferred_lft forever
    inet6 fe80::f816:3eff:fe18:/ scope link
       valid_lft forever preferred_lft forever
root@controller22::/var/log/neutron#

三、定位问题：

通过以上排查思路分析，br-int 上是有 tap设备 连接到了dhcp-namespace 中，但却是外部网络的dhcp服务ip，没有发现虚拟机所连接的192.168.168.0/24的dhcp-namespace

四、故障处理流程：

（1）找到对应网络的subnet，把 dchp 功能启用，打对勾

（2）然后到 subnet 中查看时候有 dhcp 端口且有ip，并检查 dhcp-namespace 中的 tap设备是否有了ip

（3）在次查看namespace发现多了一个dhcp-namespace

root@controller23::/var/log/neutron#ip netns show
qdhcp-cb06eada--46e7-bcd8-c9c07937231d (id: )
qrouter-3028515a-106a-4d77-b2bb-edd34ddbc7c7 (id: )
qdhcp-1a426ffe-2bf0--96a5-74402004a17b (id: )

（4）查看dhcp-namespace的 ip 配置，正好是dhcp的服务ip

root@controller23::/var/log/neutron#ip netns exec qdhcp-cb06eada--46e7-bcd8-c9c07937231d ip a
: lo: <LOOPBACK,UP,LOWER_UP> mtu  qdisc noqueue state UNKNOWN group default qlen
    link/loopback ::::: brd :::::
    inet 127.0.0.1/ scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::/ scope host
       valid_lft forever preferred_lft forever
: tap865fcb34-fc: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu  qdisc noqueue state UNKNOWN group default qlen
    link/ether fa::3e:ce:2f:9b brd ff:ff:ff:ff:ff:ff
    inet 192.168.168.2/ brd 192.168.168.255 scope global tap865fcb34-fc
       valid_lft forever preferred_lft forever
    inet 169.254.169.254/ brd 169.254.255.255 scope global tap865fcb34-fc
       valid_lft forever preferred_lft forever
    inet6 fe80::f816:3eff:fece:2f9b/ scope link
       valid_lft forever preferred_lft forever
root@controller23::/var/log/neutron#

（5）重启虚拟机虚拟机，发现获取到 ip 了

五、总结

在创建虚拟机下发请求后，dnsmasq进程会给虚拟机分配好mac地址和ip地址，并写入到/var/lib/neutron/dhcp/network-id 目录下的host文件中。虚拟机在内网中发送广播来获取ip的过程中，dnsmasq 会监听到然后将host文件中的对应ip通过dchp-namespace分配给虚拟机。

所以，在虚拟机获取ip过程中，必须虚拟机发出的包可以到达dhcp-namespace 经过的虚拟网络设备都存在且正常工作。

如果没有在subnet中开启上述的dhcp功能，那就少了一个对应网络的name-sapce dhcp服务了，所以虚拟机获取不到 ip。