「yum repolistは0です」と「yumリストは空です」を処理する方法は？

私はcentos 7ホストでdockerイメージ（gitlab-runner）を実行しています。コンテナに奇妙なことは、aptコマンドはありますがyumコマンドはありません。ところで、システムがUbuntuではなくセントースであるようですが？

root@vultr:/usr/local/java# uname -r 
3.10.0-1062.4.1.el7.x86_64

apt-get install yumを使ってyumをインストールした後、yumの更新をしたいのですが、次のような問題が発生します。どうすればいいですか？

    root@vultr:/usr/local/java# yum update      
    There are no enabled repos.
    Run "yum repolist all" to see the repos you have.
    You can enable repos with yum-config-manager --enable <repo>
    root@vultr:/usr/local/java# yum repolist all
    repolist: 0
    root@vultr:/usr/local/java# yum list
    root@vultr:/usr/local/java#
    root@vultr:/usr/local/java#
    root@vultr:/usr/local/java# yum-config-manager --enable
    Error: Trying to enable already enabled repos.
    ==================================================================================================== main ====================================================================================================
    [main]
    alwaysprompt = True
    assumeyes = False
    bandwidth = 0
    bugtracker_url = http://yum.baseurl.org/report
    cache = 0
    cachedir = /var/cache/yum
    clean_requirements_on_remove = False
    color = auto
    color_list_available_downgrade = dim,cyan
    color_list_available_install = normal
    color_list_available_reinstall = bold,underline,green
    color_list_available_upgrade = bold,blue
    color_list_installed_extra = bold,red
    color_list_installed_newer = bold,yellow
    color_list_installed_older = bold
    color_list_installed_reinstall = normal
    color_search_match = bold
    color_update_installed = normal
    color_update_local = bold
    color_update_remote = normal
    commands =
    debuglevel = 2
    diskspacecheck = True
    distroverpkg = redhat-release
    enable_group_conditionals = True
    enabled = True
    enablegroups = True
    errorlevel = 2
    exactarch = True
    exactarchlist = kernel,
       kernel-smp,
       kernel-hugemem,
       kernel-enterprise,
       kernel-bigmem,
       kernel-devel,
       kernel-PAE,
       kernel-PAE-debug
    exclude =
    exit_on_lock = False
    failovermethod = roundrobin
    gaftonmode = False
    gpgcheck = False
    group_package_types = mandatory,
       default
    groupremove_leaf_only = False
    history_list_view = single-user-commands