sudoできるユーザの追加をDockerfileに書いてみた

環境
Windows 10 Pro 1709(16299.192)
Docker version 17.12.0-ce, build c97c6d6
CentOS Linux release 7.4.1708 (Core)

前提

・「Docker for Windows」のインストール済み
・「CentOS7」の「Dockerイメージ」をダウンロード済み または 作成済み
Refer to Window10にCentOS7のdockerコンテナを作ってみた

１．「Dockerfile」を作成

Dockerfile

FROM centos
LABEL maintainer "michiru <[e-mail]>"

# ROOTにパスワードをセット
RUN echo 'root:newpassword' |chpasswd

# ユーザを作成
RUN useradd newuser
RUN echo 'newuser:newuserpass' |chpasswd
RUN echo "newuser    ALL=(ALL)       ALL" >> /etc/sudoers

# インストール済みのパッケージをアップデート＆キャッシュのクリア
RUN yum -y update && yum clean all

# sudoをインストール
RUN yum install -y sudo

２．「Dockerイメージ」の作成

PS C:\Users\UserName> docker build ./ -t useradd

３．確認

「Dockerコンテナ」の作成＆起動

PS C:\Users\UserName> docker run -it useradd

追加ユーザの確認

CentOSで実行

[root@7d831becc17d /]# su - newuser
[newuser@7d831becc17d ~]$ sudo ls

We trust you have received the usual lecture from the local System
Administrator. It usually boils down to these three things:

    #1) Respect the privacy of others.
    #2) Think before you type.
    #3) With great power comes great responsibility.

[sudo] password for newuser:
[newuser@7d831becc17d ~]$ su - root
Password:
Last failed login: Sat Feb  3 14:14:57 UTC 2018 on pts/0
There was 1 failed login attempt since the last successful login.
[root@7d831becc17d ~]# logout
[newuser@7d831becc17d ~]$ logout
[root@7d831becc17d /]# exit
PS C:\Users\UserName>

「Dockerコンテナ」の再起動

PS C:\Users\UserName> docker start 7d831becc17d
PS C:\Users\UserName> docker attach 7d831becc17d

追加ユーザで2回目のsudoでコマンド実行。（パスワードなし）

[root@7d831becc17d /]# su - newuser
Last login: Sat Feb  3 14:14:20 UTC 2018 on pts/0
[newuser@7d831becc17d ~]$ sudo touch aaa
[newuser@7d831becc17d ~]$ sudo ls
aaa
[newuser@7d831becc17d ~]$ su - root
Password:
Last login: Sat Feb  3 14:15:09 UTC 2018 on pts/0
Last failed login: Sat Feb  3 14:19:39 UTC 2018 on pts/0
There was 1 failed login attempt since the last successful login.
[root@7d831becc17d ~]#