dock一键安装命令出现这样

[root@]# dnf install -y docker-ce docker-ce-cli containerd.io docker-buildx-plugin docker-compose-plugin

回复这样的问题。
Repository baseos is listed more than once in the configuration
Repository appstream is listed more than once in the configuration
Invalid configuration value: failovermethod=priority in /etc/yum.repos.d/CentOS-epel.repo; Configuration: OptionBinding with id "failovermethod" does not exist
Repository epel is listed more than once in the configuration
CentOS Linux 8 - AppStream 0.0 B/s | 0 B 00:00
Errors during downloading metadata for repository 'appstream':
Curl error (6): Couldn't resolve host name for http://mirrorlist.centos.org/?release=8&arch=x86_64&repo=AppStream&infra=stock [Could not resolve host: mirrorlist.centos.org]
Error: Failed to download metadata for repo 'appstream': Cannot prepare internal mirrorlist: Curl error (6): Couldn't resolve host name for http://mirrorlist.centos.org/?release=8&arch=x86_64&repo=AppStream&infra=stock [Could not resolve host: mirrorlist.centos.org]

你看到的报错说明 系统还在尝试访问已经下线的 mirrorlist.centos.org，而且 repo 配置里依旧保留了旧的地址，我们得把这些旧的、重复的、带 failovermethod 的 repo 文件彻底清理或禁用掉。

下面给出“一步一命令”的修复流程，一键复制粘贴照抄即可（centos7）：

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#!/bin/bash
set -e

echo "🚀 开始为 CentOS 7 一键安装 Docker..."

# 1. 修复 DNS（可选）
echo "nameserver 8.8.8.8" > /etc/resolv.conf

# 2. 备份旧的 repo
mkdir -p /etc/yum.repos.d/bak
mv /etc/yum.repos.d/CentOS-*.repo /etc/yum.repos.d/bak/ 2>/dev/null || true
mv /etc/yum.repos.d/epel*.repo /etc/yum.repos.d/bak/ 2>/dev/null || true

# 3. 写入阿里云 Vault 源（CentOS 7）
cat > /etc/yum.repos.d/CentOS-Vault-Aliyun.repo <<'EOF'
[base]
name=CentOS-7 - Base - Aliyun Vault
baseurl=https://mirrors.aliyun.com/centos-vault/7.9.2009/os/x86_64/
gpgcheck=1
gpgkey=https://mirrors.aliyun.com/centos-vault/RPM-GPG-KEY-CentOS-7
enabled=1

[updates]
name=CentOS-7 - Updates - Aliyun Vault
baseurl=https://mirrors.aliyun.com/centos-vault/7.9.2009/updates/x86_64/
gpgcheck=1
gpgkey=https://mirrors.aliyun.com/centos-vault/RPM-GPG-KEY-CentOS-7
enabled=1

[extras]
name=CentOS-7 - Extras - Aliyun Vault
baseurl=https://mirrors.aliyun.com/centos-vault/7.9.2009/extras/x86_64/
gpgcheck=1
gpgkey=https://mirrors.aliyun.com/centos-vault/RPM-GPG-KEY-CentOS-7
enabled=1
EOF

# 4. 安装依赖
yum clean all
yum makecache
yum install -y yum-utils device-mapper-persistent-data lvm2

# 5. 添加 Docker 阿里云镜像源
yum-config-manager --add-repo https://mirrors.aliyun.com/docker-ce/linux/centos/docker-ce.repo

# 6. 安装 Docker 社区版
yum install -y docker-ce docker-ce-cli containerd.io docker-buildx-plugin docker-compose-plugin

# 7. 启动并设置开机自启
systemctl enable --now docker

# 8. 配置阿里云镜像加速
mkdir -p /etc/docker
cat > /etc/docker/daemon.json <.mirror.aliyuncs.com"]
}
EOF

# 9. 重启 Docker 生效
systemctl daemon-reload
systemctl restart docker

echo "✅ Docker 安装完成！"
docker version

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关于网页内容
你贴的两个链接 http://mirrorlist.centos.org/... 因为 CentOS 8 官方镜像下线已经 404，所以无论如何都无法解析到有效内容——这并不是网络问题，而是官方服务已关闭。我们无需再尝试访问它，直接用 Vault 镜像即可。

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一步步执行