调查了在Centos7的docker镜像中可使用systemd的选项

关于

CentOS 7的Docker镜像存在着一个问题，即引入了fakesystemd，并因此而谨慎使用。但根据风言风语，听说现在可以使用systemd，所以我进行了调查。

更新のdocker hubはここ　centos Repository | Docker Hub Registry – Repositories of Docker Images

centos:最新版本& centos:7 & centos:centos7（7322fbe74aa5）

systemdがインストールされている

[root@f9681438b272 /]# cat etc/redhat-release
CentOS Linux release 7.1.1503 (Core)
[root@f9681438b272 /]# cat /etc/centos-release
CentOS Linux release 7.1.1503 (Core)
[root@f9681438b272 /]# which systemctl
/usr/bin/systemctl
[root@f9681438b272 /]# yum list | grep systemd
systemd-container.x86_64                 208.20-6.el7.centos             @systemdcontainer
systemd-container-libs.x86_64            208.20-6.el7.centos             @systemdcontainer
golang-github-coreos-go-systemd-devel.noarch
systemd.x86_64                           208-20.el7_1.5                  updates
systemd-devel.i686                       208-20.el7_1.5                  updates
systemd-devel.x86_64                     208-20.el7_1.5                  updates
systemd-journal-gateway.x86_64           208-20.el7_1.5                  updates
systemd-libs.i686                        208-20.el7_1.5                  updates
systemd-libs.x86_64                      208-20.el7_1.5                  updates
systemd-python.x86_64                    208-20.el7_1.5                  updates
systemd-sysv.x86_64                      208-20.el7_1.5                  updates

CentOS:7.0.1406和CentOS:7.0.1406（feb2761601e7）

systemdがインストールされていない(fakesystemd)

[root@842b3d42833f /]# cat /etc/redhat-release
CentOS Linux release 7.0.1406 (Core)
[root@842b3d42833f /]# cat /etc/centos-release
CentOS Linux release 7.0.1406 (Core)
[root@842b3d42833f /]# which systemctl
/usr/bin/which: no systemctl in (/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin)
[root@842b3d42833f /]# yum list | grep systemd
fakesystemd.noarch                       1-17.el7.centos                 @fakesystemd/$releasever
systemd-libs.x86_64                      208-11.el7                      @CentOS/$releasever
golang-github-coreos-go-systemd-devel.noarch
systemd.x86_64                           208-20.el7_1.5                  updates
systemd-devel.i686                       208-20.el7_1.5                  updates
systemd-devel.x86_64                     208-20.el7_1.5                  updates
systemd-journal-gateway.x86_64           208-20.el7_1.5                  updates
systemd-libs.i686                        208-20.el7_1.5                  updates
systemd-libs.x86_64                      208-20.el7_1.5                  updates
systemd-python.x86_64                    208-20.el7_1.5                  updates
systemd-sysv.x86_64                      208-20.el7_1.5                  updates

CentOS:7.1.1503 和 CentOS:CentOS7.1.1503

systemdがインストールされていない(fakesystemd)

[root@7cd70b31a95f /]# cat /etc/redhat-release
Derived from Red Hat Enterprise Linux 7.1 (Source)
[root@7cd70b31a95f /]# cat /etc/centos-release
CentOS Linux release 7.1.1503 (Core)
[root@7cd70b31a95f /]# which systemctl
/usr/bin/which: no systemctl in (/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin)
[root@7cd70b31a95f /]# which systemctl
/usr/bin/which: no systemctl in (/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin)
[root@7cd70b31a95f /]# which systemctl
/usr/bin/which: no systemctl in (/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin)
[root@7cd70b31a95f /]# yum list | grep systemd
fakesystemd.noarch                       1-17.el7.centos                 @fakesystemd/$releasever
systemd-libs.x86_64                      208-20.el7                      @CentOS/$releasever
golang-github-coreos-go-systemd-devel.noarch
systemd.x86_64                           208-20.el7_1.5                  updates
systemd-devel.i686                       208-20.el7_1.5                  updates
systemd-devel.x86_64                     208-20.el7_1.5                  updates
systemd-journal-gateway.x86_64           208-20.el7_1.5                  updates
systemd-libs.i686                        208-20.el7_1.5                  updates
systemd-libs.x86_64                      208-20.el7_1.5                  updates
systemd-python.x86_64                    208-20.el7_1.5                  updates
systemd-sysv.x86_64                      208-20.el7_1.5                  updates

总结

听说即使是相同标签的docker image也会定期更新，所以最好根据哈希值来判断。另外，我想知道为什么要停止使用fakesystemd是什么原因。