openstack组件服务的入口寻找方法

在centos7系统上，安装openstack服务以后，可以通过以下命令，查找到该系统上，已经安装的openstack服务

[root@xzto01n010027244133 ~]# systemctl list-unit-files | grep openstack
openstack-cinder-api.service                  enabled 
openstack-cinder-backup.service               disabled
openstack-cinder-scheduler.service            enabled 
openstack-cinder-volume.service               disabled
openstack-glance-api.service                  enabled 
openstack-glance-glare.service                disabled
openstack-glance-registry.service             enabled 
openstack-glance-scrubber.service             disabled
openstack-nova-api.service                    enabled 
openstack-nova-conductor.service              enabled 
openstack-nova-console.service                disabled
openstack-nova-consoleauth.service            disabled
openstack-nova-metadata-api.service           disabled
openstack-nova-novncproxy.service             enabled 
openstack-nova-os-compute-api.service         disabled
openstack-nova-scheduler.service              enabled 
openstack-nova-xvpvncproxy.service            disabled
[root@xzto01n010027244133 ~]# 

neutron服务命名比较特殊，通过如下命令行进行查找

[root@xzto01n010027244133 ~]# systemctl list-unit-files | grep neutron
neutron-dhcp-agent.service                    disabled
neutron-l3-agent.service                      disabled
neutron-linuxbridge-cleanup.service           disabled
neutron-metadata-agent.service                disabled
neutron-netns-cleanup.service                 disabled
neutron-openvswitch-agent.service             disabled
neutron-ovs-cleanup.service                   disabled
neutron-server.service                        enabled 

所有可用的单元文件存放在 /usr/lib/systemd/system/ 和 /etc/systemd/system/ 目录（后者优先级更高），openstack各服务的文件一般放在/usr/lib/systemd/system/目录下，命令如下：

[root@xzto01n010027244133 ~]# ls -lh /usr/lib/systemd/system/ | grep openstack
-rw-r--r--  1 root root  343 Nov 12  2017 openstack-cinder-api.service
-rw-r--r--  1 root root  335 Nov 12  2017 openstack-cinder-backup.service
-rw-r--r--  1 root root  344 Nov 12  2017 openstack-cinder-scheduler.service
-rw-r--r--  1 root root  389 Nov 12  2017 openstack-cinder-volume.service
-rw-r--r--  1 root root  285 Mar 21  2017 openstack-glance-api.service
-rw-r--r--  1 root root  256 Mar 21  2017 openstack-glance-glare.service
-rw-r--r--  1 root root  258 Mar 21  2017 openstack-glance-registry.service
-rw-r--r--  1 root root  254 Mar 21  2017 openstack-glance-scrubber.service
-rw-r--r--  1 root root  230 Oct 15 10:43 openstack-nova-api.service
-rw-r--r--  1 root root  242 Oct 15 10:43 openstack-nova-conductor.service
-rw-r--r--  1 root root  251 Oct 15 10:43 openstack-nova-consoleauth.service
-rw-r--r--  1 root root  244 Oct 15 10:43 openstack-nova-console.service
-rw-r--r--  1 root root  248 Oct 15 10:43 openstack-nova-metadata-api.service
-rw-r--r--  1 root root  304 Oct 15 10:43 openstack-nova-novncproxy.service
-rw-r--r--  1 root root  248 Oct 15 10:43 openstack-nova-os-compute-api.service
-rw-r--r--  1 root root  242 Oct 15 10:43 openstack-nova-scheduler.service
-rw-r--r--  1 root root  216 Oct 15 10:43 openstack-nova-xvpvncproxy.service
[root@xzto01n010027244133 ~]# cd /usr/lib/systemd/system/ 
[root@xzto01n010027244133 system]# pwd
/usr/lib/systemd/system

查看neutron服务文件，ls -lh /usr/lib/systemd/system/ | grep neutron，命令行如下：

[root@xzto01n010027244133 system]# ls -lh /usr/lib/systemd/system/ | grep neutron
-rw-r--r--  1 root root  516 Oct 15 11:23 neutron-dhcp-agent.service
-rw-r--r--  1 root root  512 Oct 15 11:23 neutron-l3-agent.service
-rw-r--r--  1 root root 1.1K Oct 15 11:23 neutron-linuxbridge-cleanup.service
-rw-r--r--  1 root root  536 Oct 15 11:23 neutron-metadata-agent.service
-rw-r--r--  1 root root  987 Oct 15 11:23 neutron-netns-cleanup.service
-rw-r--r--  1 root root  734 Oct 15 11:23 neutron-openvswitch-agent.service
-rw-r--r--  1 root root 1.0K Oct 15 11:23 neutron-ovs-cleanup.service
-rw-r--r--  1 root root  569 Oct 15 11:23 neutron-server.service

通过服务文件找对应的启动脚本

[root@xzto01n010027244133 system]# cat openstack-nova-api.service
[Unit]
Description=OpenStack Nova API Server
After=syslog.target network.target

[Service]
Type=notify
NotifyAccess=all
TimeoutStartSec=0
Restart=always
User=nova
ExecStart=/usr/bin/nova-api

[Install]
WantedBy=multi-user.target

[root@xzto01n010027244133 system]# pwd
/usr/lib/systemd/system
[root@xzto01n010027244133 system]# 

重点是红线部分，openstack-nova-api的启动命令，启动脚本为/usr/bin/nova-api

通过启动命令找对应的入口代码

[root@xzto01n010027244133 system]# cat /usr/bin/nova-api
#!/usr/bin/python2
# PBR Generated from u'console_scripts'

import sys

from nova.cmd.api import main


if __name__ == "__main__":
    sys.exit(main())
[root@xzto01n010027244133 system]# pwd
/usr/lib/systemd/system