Devstack — screen 调试工具的使用

目录

为什么要使用 screen 工具 ？

当 Devstack 编译安装完 OpenStack 后，我们是不能通过 init 脚本或者 service 指令来与各个 Openstack Services 进行交互的。
也就是说我们无法像使用 RDO 安装那样可以通过 systemctl restart openstack-nova-api.serice 来重启 nova-api 服务。
因为 Devstack 的设计初衷是便于 Openstack developers 开发和调试 Openstack 代码，所以 Devstack 只能通过 screen 来启动服务，而且每一个 Openstack Services 都是一个子 screen 。Devstack 部署的 Openstack 相信大家都会遇见一个问题，当物理机重启后 Services 怎么重启，其实只需要执行 ./rejoin-stack.sh就好了，其原理跟启动 screen 是一样的，将没有启动的 Services 启动，已经启动的不会被覆盖，启动完成后自动进入 screen 。在 screen 中我们不仅仅可以启动 Services ，我们还能够非常清晰简便的切换查看各个 Services 的 Log 。本篇主要介绍了 screen 的使用，应该是多有 Openstack 开发者的必备技能吧。

启动 screen

screen -x stack

注意：如果启动失败，可以尝试在执行下面的指令之后在重新尝试启动：

script /dev/null

可以看见 Terminal 最下方有一串白色的字符串，其中的每一个数字对应一个子 screen 也就是一个 Openstack services 。
我们可以通过快捷键+数字的组合来切换到对应的子 screen 。’ * ‘ 所在的处的位置表示当前的 screen 是该 Service 的 screen。EXAMPLE:

14$(L) c-api  15-$(L) c-sch   16$(L) c-vol*

screen 的切换(常用)

• CTRL+a + number ：切换到数字 number 对应的子 screen 中(number == 0 ⇒ shell)
  

• CTRL + a + ’ ⇒ 输入number：当 number > 10 时，可以使用这种方法来切换，当然 number < 10 时，也可以使用。 推荐*

• CTRL + a + n ：切换到下一个 screen

• CTRL + a + p：切换到前一个 screen

• CTRL + a + a：返回上一个 screen

• CRTL + a + 稍等一秒 + shift + ‘：显示所有的 screen 的列表

• CTRL + [：开始滚动模式 ，然后可以使用上下左右键滚屏

• CTRL + ]：退出滚动模式

• CTRL + a + H ：保存 screen 到日志文件，再按一次停止保存

• CTRL + a + ?：获取帮助信息

退出和重新连接 screen

• 退出：

  1. CRTL + a + ’ ⇒ 输入 0 ，然后再输入screen -d
  2. CRTL + a + d

• 重新连接：

#查看当前用户启动的 screenfanguiju@jmilkfan:~$ screen -ls   There is a screen on:    20569.stack (08/02/16 11:36:47) (Detached)1 Socket in /var/run/screen/S-fanguiju.#上一条指令的Outputfanguiju@jmilkfan:~$ screen -r 20569  

Restart Openstack Services

• CTRL + c：终止一个 screen ，Stop the services

• 进入希望 Restart 的 Openstack Services 的 screen 中，然后输入 CTRL + c 结束这个进程，输入 ↑并重新执行上一条指令。
  

screen 指令选项总览

fanguiju@fanguiju:~/devstack$ screen --help Use: screen [-opts] [cmd [args]] or: screen -r [host.tty]Options:-4            Resolve hostnames only to IPv4 addresses.-6            Resolve hostnames only to IPv6 addresses.-a            Force all capabilities into each window's termcap.-A -[r|R]     Adapt all windows to the new display width & height.-c file       Read configuration file instead of '.screenrc'.-d (-r)       Detach the elsewhere running screen (and reattach here).-dmS name     Start as daemon: Screen session in detached mode.-D (-r)       Detach and logout remote (and reattach here).-D -RR        Do whatever is needed to get a screen session.-e xy         Change command characters.-f            Flow control on, -fn = off, -fa = auto.-h lines      Set the size of the scrollback history buffer.-i            Interrupt output sooner when flow control is on.-l            Login mode on (update /var/run/utmp), -ln = off.-ls [match]   or -list. Do nothing, just list our SockDir [on possible matches].-L            Turn on output logging.-m            ignore $STY variable, do create a new screen session.-O            Choose optimal output rather than exact vt100 emulation.-p window     Preselect the named window if it exists.-q            Quiet startup. Exits with non-zero return code if unsuccessful.-r [session]  Reattach to a detached screen process.-R            Reattach if possible, otherwise start a new session.-s shell      Shell to execute rather than $SHELL.-S sockname   Name this session <pid>.sockname instead of <pid>.<tty>.<host>.-t title      Set title. (window's name).-T term       Use term as $TERM for windows, rather than "screen".-U            Tell screen to use UTF-8 encoding.-v            Print "Screen version 4.01.00devel (GNU) 2-May-06".-wipe [match] Do nothing, just clean up SockDir [on possible matches].-x            Attach to a not detached screen. (Multi display mode).-X            Execute <cmd> as a screen command in the specified session.

Openstack 重启指令

screen 有一个非常不方便的地方就是，有些电脑不能通过 CTRL + [|] 来实现屏幕的滚动，这根本无法很好的观察 Log ，所以建议将启动指令 Copy 另外一个 Terminal 执行。
注意：下列的指令的/opt/stack/参数因各人的安装路径不同而异。
restart glance:

glance-api

/usr/local/bin/glance-api --config-file=/etc/glance/glance-api.conf & echo $! >/opt/stack/status/stack/g-api.pid; fg || echo "g-api failed to start" | tee "/opt/stack/status/stack/g-api.failure"

glance-registry

/usr/local/bin/glance-registry --config-file=/etc/glance/glance-registry.conf & echo $! >/opt/stack/status/stack/g-reg.pid; fg || echo "g-reg failed to start" | tee "/opt/stack/status/stack/g-reg.failure"

nova-api

sudo /usr/local/bin/nova-api & echo $! >/opt/stack/status/stack/n-api.pid; fg || echo "n-api failed to start" | tee "/opt/stack/status/stack/n-api.failure"

nova-conduter

/usr/local/bin/nova-conductor --config-file /etc/nova/nova.conf & echo $! >/opt/stack/status/stack/n-cond.pid; fg || echo "n-cond failed to start" | tee "/opt/stack/status/stack/n-cond.failure"

nova-crt

/usr/local/bin/nova-cert --config-file /etc/nova/nova.conf & echo $! >/opt/stack/status/stack/n-crt.pid; fg || echo "n-crt failed to start" | tee "/opt/stack/status/stack/n-crt.failure"

nova-network

/usr/local/bin/nova-network --config-file /etc/nova/nova.conf & echo $! >/opt/stack/status/stack/n-net.pid; fg || echo "n-net failed to start" | tee "/opt/stack/status/stack/n-net.failure"

nova-scheduter

/usr/local/bin/nova-scheduler --config-file /etc/nova/nova.conf & echo $! >/opt/stack/status/stack/n-sch.pid; fg || echo "n-sch failed to start" | tee "/opt/stack/status/stack/n-sch.failure"

nova-novnc

/usr/local/bin/nova-novncproxy --config-file /etc/nova/nova.conf --web /opt/stack/noVNC & echo $! >/opt/stack/status/stack/n-novnc.pid; fg || echo "n-novnc failed to start" | tee "/opt/stack/status/stack/n-novnc.failure"

nova-cauth

/usr/local/bin/nova-consoleauth --config-file /etc/nova/nova.conf & echo $! >/opt/stack/status/stack/n-cauth.pid; fg || echo "n-cauth failed to start" | tee "/opt/stack/status/stack/n-cauth.failure"

nova-cpu

sg libvirtd '/usr/local/bin/nova-compute --config-file /etc/nova/nova.conf' & echo $! >/opt/stack/status/stack/n-cpu.pid; fg || echo "n-cpu failed to start" | tee "/opt/stack/status/stack/n-cpu.failure"

restart cinder:

c-api

/usr/local/bin/cinder-api --config-file /etc/cinder/cinder.conf & echo $! >/opt/stack/status/stack/c-api.pid; fg || echo "c-api failed to start" | tee "/opt/stack/status/stack/c-api.failure"

c-sch

/usr/local/bin/cinder-scheduler --config-file /etc/cinder/cinder.conf & echo $! >/opt/stack/status/stack/c-sch.pid; fg || echo "c-sch failed to start" | tee "/opt/stack/status/stack/c-sch.failure"

c-vol

/usr/local/bin/cinder-volume --config-file /etc/cinder/cinder.conf & echo $! >/opt/stack/status/stack/c-vol.pid; fg || echo "c-vol failed to start" | tee "/opt/stack/status/stack/c-vol.failure"