docker exec可以使用--user参数指定root用户，进入安装vi即可：
[opc@oci-001 ~]$ docker exec -it --user root testdb bash
bash-4.2# vi
bash: vi: command not found
bash-4.2# yum install vi
Loaded plugins: ovl
ol7_UEKR5 | 3.0 kB 00:00:00
ol7_latest | 3.6 kB 00:00:00
(1/5): ol7_UEKR5/x86_64/updateinfo | 186 kB 00:00:00
(2/5): ol7_latest/x86_64/group_gz | 136 kB 00:00:00
(3/5): ol7_latest/x86_64/updateinfo | 3.4 MB 00:00:00
(4/5): ol7_UEKR5/x86_64/primary_db | 34 MB 00:00:01
(5/5): ol7_latest/x86_64/primary_db | 37 MB 00:00:01
Resolving Dependencies
--> Running transaction check
---> Package vim-minimal.x86_64 2:7.4.629-8.0.1.el7_9 will be installed
--> Finished Dependency Resolution
Dependencies Resolved
====================================================================================================================================================================================
Package Arch Version Repository Size
====================================================================================================================================================================================
Installing:
vim-minimal x86_64 2:7.4.629-8.0.1.el7_9 ol7_latest 443 k
Transaction Summary
====================================================================================================================================================================================
Install 1 Package
Total download size: 443 k
Installed size: 914 k
Is this ok [y/d/N]: y
Downloading packages:
vim-minimal-7.4.629-8.0.1.el7_9.x86_64.rpm | 443 kB 00:00:00
Running transaction check
Running transaction test
Transaction test succeeded
Running transaction
Installing : 2:vim-minimal-7.4.629-8.0.1.el7_9.x86_64 1/1
Verifying : 2:vim-minimal-7.4.629-8.0.1.el7_9.x86_64 1/1
Installed:
vim-minimal.x86_64 2:7.4.629-8.0.1.el7_9
Complete!
bash-4.2# vi
bash-4.2#