新的OCI實例，OS選擇的是OEL7.9，初始環境是沒有安裝docker的，我們可以直接使用yum安裝，之后啟動docker服務：
[opc@oci-001 ~]$ sudo yum install docker
[opc@oci-001 ~]$ sudo systemctl start docker
因為默認登陸用戶是opc，安裝后使用docker命令都需要sudo，否則會報錯權限問題：
[opc@oci-001 ~]$ docker ps
Got permission denied while trying to connect to the Docker daemon socket at unix:///var/run/docker.sock: Get "http://%2Fvar%2Frun%2Fdocker.sock/v1.40/containers/json": dial unix /var/run/docker.sock: connect: permission denied
[opc@oci-001 ~]$ sudo docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
為了操作方便，我們需要將opc用戶加入到docker組中：
[opc@oci-001 run]$ sudo gpasswd -a opc docker
正在將用戶“opc”加入到“docker”組中
[opc@oci-001 run]$ docker ps
Got permission denied while trying to connect to the Docker daemon socket at unix:///var/run/docker.sock: Get "http://%2Fvar%2Frun%2Fdocker.sock/v1.40/containers/json": dial unix /var/run/docker.sock: connect: permission denied
[opc@oci-001 run]$ id
uid=1000(opc) gid=1000(opc) 組=1000(opc),4(adm),10(wheel),190(systemd-journal) 環境=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023
[opc@oci-001 run]$ id opc
uid=1000(opc) gid=1000(opc) 組=1000(opc),4(adm),10(wheel),190(systemd-journal),992(docker)
[opc@oci-001 run]$ id
uid=1000(opc) gid=1000(opc) 組=1000(opc),4(adm),10(wheel),190(systemd-journal) 環境=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023
上面看到加入docker組后依然報錯，但其實通過id和id opc驗證很容易發現是當前shell沒有生效，
此時需要重新登陸opc用戶，再次嘗試可以正常執行docker命令而無需sudo操作：
Enter your username: opc
Last login: Wed Nov 10 23:47:49 2021 from xxx.xxx.xxx.xxx
[opc@oci-001 ~]$ id
uid=1000(opc) gid=1000(opc) 組=1000(opc),4(adm),10(wheel),190(systemd-journal),992(docker) 環境=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023
[opc@oci-001 ~]$ docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
[opc@oci-001 ~]$ docker version
Client: Docker Engine - Community
Version: 19.03.11-ol
API version: 1.40
Go version: go1.16.2
Git commit: 9bb540d
Built: Fri Jul 23 01:33:55 2021
OS/Arch: linux/amd64
Experimental: false
Server: Docker Engine - Community
Engine:
Version: 19.03.11-ol
API version: 1.40 (minimum version 1.12)
Go version: go1.16.2
Git commit: 9bb540d
Built: Fri Jul 23 01:32:08 2021
OS/Arch: linux/amd64
Experimental: false
Default Registry: docker.io
containerd:
Version: v1.4.8
GitCommit: 7eba5930496d9bbe375fdf71603e610ad737d2b2
runc:
Version: 1.0.0-rc95
GitCommit: 2856f01
docker-init:
Version: 0.18.0
GitCommit: fec3683
此時就可以正常操作docker命令了，但是還有一個情況，如果需要登陸需要登陸信息的docker鏡像倉庫，比如Oracle的官方鏡像倉庫：
[opc@oci-001 ~]$ docker login container-registry.oracle.com
Username: xxx@xx.com
Password:
WARNING! Your password will be stored unencrypted in /home/opc/.docker/config.json.
Configure a credential helper to remove this warning. See
https://docs.docker.com/engine/reference/commandline/login/#credentials-store
Login Succeeded
成功登陸后，可以正常拉取對應鏡像：
[opc@oci-001 ~]$ docker pull container-registry.oracle.com/database/enterprise:19.3.0.0
Trying to pull repository container-registry.oracle.com/database/enterprise ...
19.3.0.0: Pulling from container-registry.oracle.com/database/enterprise
86607bb85307: Pull complete
9426f6bfa092: Pull complete
16f82e6c6196: Pull complete
3b3cb340bf3a: Pull complete
914616be8a89: Pull complete
72eda44db682: Pull complete
4f4fb700ef54: Pull complete
930126d48988: Pull complete
74776159d717: Pull complete
a75af7560303: Pull complete
768777aee4bd: Pull complete
83bc762e273b: Pull complete
40ae2cf39a7a: Pull complete
97f3b11e6fb5: Pull complete
49b970fb5707: Pull complete
49801e1d38a0: Pull complete
e0d849ef2418: Pull complete
31d732a7744f: Pull complete
760939c383f0: Pull complete
5c2969cb34b8: Pull complete
Digest: sha256:ea9cd805ec49368fd288323e3f41d6c6e45698813e2ae89fd5d097c026ab5aa6
Status: Downloaded newer image for container-registry.oracle.com/database/enterprise:19.3.0.0
container-registry.oracle.com/database/enterprise:19.3.0.0
注：之前做測試過程中，最開始沒有將opc加入到docker組中，所以使用sudo操作，比如登陸用 sudo docker login方式登陸，配置文件會被存放到/root/.docker/config.json，給后面運維會帶來一些麻煩。所以建議大家最開始就配置規划好使用docker的用戶。