OpenStack部署裸金属无法启动cloud-init

• • 云环境：OpenStack Mitaka
• 裸机系统：BCLinux 8
• cloud-init 19

问题

• 通过OpenStack部署裸金属，系统镜像安装完毕后重启，cloud-init无法启动（共四个服务都没有启动）。同qcow2镜像在KVM环境里可以正常进行初始化
• 如果使用cloud-init 18.2，可以正常启动（先前用rhel7.8测试通过），但一旦使用18.5以上就会出现上述问题。
• 使用本地单独KVM环境测试，18.5以上的cloud-init同样无法启动。

分析

• cloud-init 18.5相比18.2，有如下区别：

  • 18.2中四个服务都在multi-user.target.wants中，跟随系统启动；18.5中，四个服务在cloud-init.target.wants中，cloud-init.target被设置成在multi-user.target之后启动

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    # 18.5 [root@localhost ~]# ls -l /etc/systemd/system/cloud-init.target.wants/ total 0 lrwxrwxrwx. 1 root root 44 May 17 05:15 cloud-config.service -> /usr/lib/systemd/system/cloud-config.service lrwxrwxrwx. 1 root root 43 May 17 05:15 cloud-final.service -> /usr/lib/systemd/system/cloud-final.service lrwxrwxrwx. 1 root root 48 May 17 05:15 cloud-init-local.service -> /usr/lib/systemd/system/cloud-init-local.service lrwxrwxrwx. 1 root root 42 May 17 05:15 cloud-init.service -> /usr/lib/systemd/system/cloud-init.service ## cloud-init.target # /usr/lib/systemd/system/cloud-init.target # cloud-init target is enabled by cloud-init-generator # To disable it you can either: # a.) boot with kernel cmdline of 'cloud-init=disabled' # b.) touch a file /etc/cloud/cloud-init.disabled [Unit] Description=Cloud-init target After=multi-user.target # 18.2 [root@localhost multi-user.target.wants]# ls -l total 0 lrwxrwxrwx. 1 root root 44 Dec 5 2018 cloud-config.service -> /usr/lib/systemd/system/cloud-config.service lrwxrwxrwx. 1 root root 43 Dec 5 2018 cloud-final.service -> /usr/lib/systemd/system/cloud-final.service lrwxrwxrwx. 1 root root 48 Dec 5 2018 cloud-init-local.service -> /usr/lib/systemd/system/cloud-init-local.service lrwxrwxrwx. 1 root root 42 Dec 5 2018 cloud-init.service -> /usr/lib/systemd/system/cloud-init.service

  • 18.5多了一个system-generators下的脚本，这个脚本根据是否能找到datasource决定cloud-init服务是否启动：

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    # /usr/lib/systemd/system-generators/cloud-init-generator ... # enable AND ds=found == enable # enable AND ds=notfound == disable # disable || <any> == disabled if [ "$result" = "$ENABLE" ]; then debug 1 "checking for datasource" check_for_datasource ds=$_RET if [ "$ds" = "$NOTFOUND" ]; then debug 1 "cloud-init is enabled but no datasource found, disabling" result="$DISABLE" fi fi ...

    • 如果没有找到数据源，就会把已经enable的服务再disable（就是把链接文件删掉）

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    elif [ "$result" = "$DISABLE" ]; then if [ -f "$link_path" ]; then if rm -f "$link_path"; then debug 1 "disabled. removed existing $link_path" else ret=$? debug 0 "[$ret] disable failed, remove $link_path" fi else debug 1 "already disabled: no change needed [no $link_path]" fi if [ -e "$RUN_ENABLED_FILE" ]; then rm -f "$RUN_ENABLED_FILE" fi else debug 0 "unexpected result '$result' 'ds=$ds'" ret=3 fi return $ret

    参考：https://forums.opensuse.org/t/cloud-init-does-not-run/131727/7

解决方法

1

• 最简单的办法是改成和18.2一样的方式，让四个服务依附于multi-user.target启动

2

• cloud-init-generator脚本中在查找数据源的时候，会调用/usr/libexec/cloud-init/ds-identify脚本，这个脚本大概的功能，是检查ds-identify配置文件，在这个配置文件中，可以通过自定义策略来改变默认策略，达到控制服务启动的作用。

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# shellcheck disable=2015,2039,2162,2166,3043
#
# ds-identify is configured via /etc/cloud/ds-identify.cfg
# or on the kernel command line. It takes the following inputs:
#
# datasource: can specify the datasource that should be used.
#   kernel command line option: ci.datasource=<dsname> or ci.ds=<dsname>
#   example line in /etc/cloud/ds-identify.cfg:
#      datasource: Ec2
#
# policy: a string that indicates how ds-identify should operate.
#
#   The format is:
#        <mode>,found=value,maybe=value,notfound=value
#   default setting is:
#     search,found=all,maybe=all,notfound=disabled
#
#   kernel command line option: ci.di.policy=<policy>
#   example line in /etc/cloud/ds-identify.cfg:
#      policy: search,found=all,maybe=none,notfound=disabled

• 新建/etc/cloud/ds-identify.cfg，在其中写入：

  1	policy: search,found=all,maybe=none,notfound=enabled

• notfound被改为enabled，即便没有找到数据源，cloud-init也可以正常启动。