Yum Repository詳解

什麼是YUM

YUM(Yellowdog Updater Modified)是Fedora、CentOS、RedHat中的軟件包管理器。基於 RPM 包管理,YUM通過分析RPM header數據,自動處理依賴關係,從指定服務器自動下載安裝所有依賴的軟件包。

常用yum命令

安裝軟件

# yum install package1 [package2] [...]

重裝軟件

# yum reinstall package1 [package2] [...]

刪除軟件

# yum remove package1 [package2] [...]
或
# yum erase package1 [package2] [...]

升級軟件

# yum update [package1] [package2] [...]
或
# yum upgrade [package1] [package2] [...]

當不指定參數時,升級所有軟件。

檢查更新

# yum check-update

查詢信息

# yum info [...]

查看可用的RPM包

# yum list [...]

搜索軟件

# yum search string1 [string2] [...]

清除緩存

# yum clean [ packages | metadata | expire-cache | rpmdb | plugins | all ]

下載並使metadata可用

# yum makecache [fast]

解決yum安裝問題

可先試以下命令:

# yum clean all
# yum makecache

Structure needs cleaning
yum安裝報錯:Structure needs cleaning,可使用package-cleanup查找有問題的包,刪除後再重新安裝:

# package-cleanup --problems or --leaves or --orphans or --oldkernels
# rpm -e xxxxxxxxx

rpmdb open failed
錯誤信息如下:

error: db5 error(-30973) from dbenv->open: BDB0087 DB_RUNRECOVERY: Fatal error, run database recovery
error: cannot open Packages index using db5 -  (-30973)
error: cannot open Packages database in /var/lib/rpm
CRITICAL:yum.main:

Error: rpmdb open failed

解決方法:

# rm -f /var/lib/rpm/__db*
# rpm --rebuilddb

更多yum工具,請查看yum-utils:

# man yum-utils

YUM Repository

我們要使用YUM,必須要先找到適合的YUM Server,配置YUM Repositry。CentOS有很多的鏡像站點供全世界軟件更新之用。CentOS安裝後已配置好這些Yum Repository,配置文件位於/etc/yum.repos.d目錄下,文件擴展名爲repo,如您不慎誤刪可執行如下命令重新安裝:

#rpm -Uvh http://mirror.centos.org/centos/7/os/x86_64/Packages/centos-release-7-6.1810.2.el7.centos.x86_64.rpm

repo文件

下面我們看一下CentOS-Base.repo的內容:

# CentOS-Base.repo
#
# The mirror system uses the connecting IP address of the client and the
# update status of each mirror to pick mirrors that are updated to and
# geographically close to the client.  You should use this for CentOS updates
# unless you are manually picking other mirrors.
#
# If the mirrorlist= does not work for you, as a fall back you can try the 
# remarked out baseurl= line instead.
#
#

[base]
name=CentOS-$releasever - Base
mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=os&infra=$infra
#baseurl=http://mirror.centos.org/centos/$releasever/os/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7

#released updates 
[updates]
name=CentOS-$releasever - Updates
mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$baasearch&repo=updates&infra=$infra
#baseurl=http://mirror.centos.org/centos/$releasever/updates/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7

#additional packages that may be useful
[extras]
name=CentOS-$releasever - Extras
mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=extras&infra=$infra
#baseurl=http://mirror.centos.org/centos/$releasever/extras/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7

#additional packages that extend functionality of existing packages
[centosplus]
name=CentOS-$releasever - Plus
mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=centosplus&infra=$infra
#baseurl=http://mirror.centos.org/centos/$releasever/centosplus/$basearch/
gpgcheck=1
enabled=0
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7

從文件頭的說明我們知道,鏡像系統使用客戶端的IP地址和每個鏡像的更新狀態來選取在地理位置上靠近客戶端的鏡像,如mirrorlist不工作時可以使用baseurl。
使用Yum安裝軟件時可以看到用了哪些鏡像:

Loaded plugins: fastestmirror, langpacks
Loading mirror speeds from cached hostfile
 * base: mirrors.huaweicloud.com
 * extras: mirrors.tuna.tsinghua.edu.cn
 * updates: mirrors.tuna.tsinghua.edu.cn

使用了哪些Repository:

=======================================================================================================================
 Package                       Arch                    Version                       Repository                   Size
=======================================================================================================================
Removing:                                  
 vim-enhanced                  x86_64                  2:7.4.160-5.el7               @base                       2.2 M

Transaction Summary                        
=======================================================================================================================

參數說明:
[repositoryid] 倉庫ID,名稱任意但不能重複
baseurl yum倉庫URL,其下必須含有`repodata'目錄,可以是http://、ftp:// 或 file:// URL。一個baseurl可以指定多個URL:

baseurl=url://server1/path/to/repository/
        url://server2/path/to/repository/
        url://server3/path/to/repository/

mirrorlist 指向一文件的URL,其內容爲baseurl列表
enabled 是否啓用這個倉庫,0表示不啓用,1表示啓用,默認啓用。如爲安裝某個軟件自己配置了一個倉庫,但又要不影響其他軟件安裝,可以設爲0,安裝這個軟件時再啓用:yum --enablerepo=repoid
gpgcheck 是否進行簽名合法性檢測,0表示不啓用,1表示啓用,默認啓用
gpgkey gpgkey的路徑,可以爲本地路徑,也可以爲網絡路徑

$releasever 發行版本,可執行yum whatprovides 'system-release(releasever)' centos-release或yum version查看
$basearch 系統架構
$infra 其值可查看文件/etc/yum/vars/infra,此參數目前尚未使用。

CentOS 7,$releasever值爲7,$basearch值爲x86_64,$infra值爲stock,替換後extras mirrorlist的值爲:

http://mirrorlist.centos.org/?release=7&arch=x86_64&repo=extras&infra=stock

在瀏覽器中查看輸出如下結果:

http://mirrors.njupt.edu.cn/centos/7.6.1810/extras/x86_64/
http://mirrors.cn99.com/centos/7.6.1810/extras/x86_64/
http://mirrors.nwsuaf.edu.cn/centos/7.6.1810/extras/x86_64/
http://mirror.lzu.edu.cn/centos/7.6.1810/extras/x86_64/
http://mirrors.nju.edu.cn/centos/7.6.1810/extras/x86_64/
http://mirrors.aliyun.com/centos/7.6.1810/extras/x86_64/
http://mirrors.huaweicloud.com/centos/7.6.1810/extras/x86_64/
http://mirrors.neusoft.edu.cn/centos/7.6.1810/extras/x86_64/
http://mirrors.tuna.tsinghua.edu.cn/centos/7.6.1810/extras/x86_64/
http://mirrors.cqu.edu.cn/CentOS/7.6.1810/extras/x86_64/

yum.conf

Yum配置文件/etc/yum.conf,可使用man yum.conf查看各配置項的意義。

# 定義全局配置選項
[main]
# yum緩存目錄
cachedir=/var/cache/yum/$basearch/$releasever
# 1或0,安裝成功後是否保存header和package
keepcache=0
# debug message輸出級別,0 - 10
debuglevel=2
logfile=/var/log/yum.log
exactarch=1
obsoletes=1
# 1或0,是否執行gpg簽名檢查
gpgcheck=1
# 1或0,是否啓用yum plugins
plugins=1
installonly_limit=5
bugtracker_url=http://bugs.centos.org/set_project.php?project_id=23&ref=http://bugs.centos.org/bug_report_page.php?category=yum
# 指定一個包,Yum據此判斷髮行版本來設置配置文件中的$releasever,可執行yum whatprovides 'system-release(releasever)' centos-release或yum version查看
distroverpkg=centos-release

#  This is the default, if you make this bigger yum won't see if the metadata
# is newer on the remote and so you'll "gain" the bandwidth of not having to
# download the new metadata and "pay" for it by yum not having correct
# information.
#  It is esp. important, to have correct metadata, for distributions like
# Fedora which don't keep old packages around. If you don't like this checking
# interupting your command line usage, it's much better to have something
# manually check the metadata once an hour (yum-updatesd will do this).
# metadata_expire=90m

# PUT YOUR REPOS HERE OR IN separate files named file.repo
# in /etc/yum.repos.d

配置Repository

有時我們安裝的軟件不能從官方Repository獲得,需要使用其它的Repository,比如:
EPEL Repository Mirrors
ELRepo Repository

Repository站點一般都提供了rpm包,安裝後會自動配置repo。
EPEL CentOS/RHEL 7

# rpm -Uvh https://dl.fedoraproject.org/pub/epel/epel-release-latest-7.noarch.rpm

EPEL CentOS/RHEL 6

# rpm -Uvh https://dl.fedoraproject.org/pub/epel/epel-release-latest-6.noarch.rpm

ELRepo CentOS/RHEL 7/6

# rpm --import https://www.elrepo.org/RPM-GPG-KEY-elrepo.org
# rpm -Uvh https://www.elrepo.org/elrepo-release-7.0-3.el7.elrepo.noarch.rpm
# rpm -Uvh https://www.elrepo.org/elrepo-release-6-8.el6.elrepo.noarch.rpm

或自己在/etc/yum.repos.d目錄創建repo文件,比如

[ali-extras]
name=ali centos7 extras
baseurl=https://mirrors.aliyun.com/centos/7/extras/x86_64/
enable=1
gpgcheck=0
gpgkey=https://mirrors.aliyun.com/centos/RPM-GPG-KEY-CentOS-7

注意baseurl地址下必須含有repodata文件夾,repodata中保存了rpm依賴關係等數據。

如不知道哪個Repository有您需要的rpm,可通過以下網站查找:
Package search
RPM Search
RPM Find

Redhat訂閱

默認,Redhat僅base repository是可用的,若要使用其它repository需要訂閱後啓用,如下:

subscription-manager register
subscription-manager list --available
subscription-manager attach --pool=8a85f98b62dd96fc0162f04efb0e6350
subscription-manager repos --enable rhel-7-server-extras-rpms
subscription-manager repos --enable rhel-7-server-rpms

搭建Repository

CentOS ISO鏡像作爲Repository

CentOS ISO鏡像中含有大量的RPM包,可以用作Repository。
先執行如下命令mount iso:

# mount -o loop CentOS-7-x86_64-DVD-1804.iso /mnt

然後創建repo文件,如下:
/etc/yum.repos.d/centos-iso.repo

[centosiso]
name=CentOS DVD ISO
baseurl=file:///mnt
enabled=1
gpgcheck=1
gpgkey=file:///mnt/RPM-GPG-KEY-CentOS-7

搭建自己的Repository

搭建自己的Repository可以避免重複下載rpm,也可以存放公司內部的rpm。搭建步驟如下:

  1. 安裝createrepo
# yum install createrepo
  1. 創建Repository目錄
# mkdir /repository
  1. 獲取rpm

同步Repository:

# reposync -d --norepopath -r extras -p /repository/centos/7/extras/x86_64/

獲取單獨的rpm可使用yumdownloader,比如:

# yumdownloader --destdir /repository/centos/7/extras/x86_64/Packages python-docker-py
  1. 創建/更新repodata
# createrepo --update /repository/centos/7/extras/x86_64/
  1. 安裝配置Apache

若要從外部訪問Repository需安裝apache並配置目錄/repository。

# yum install httpd
# systemctl enable httpd

可以簡單的編輯/etc/httpd/conf/httpd.conf,將DocumentRoot改爲/repository,如下:

DocumentRoot "/repository"
<Directory "/repository">
  Options Indexes FollowSymLinks
    AllowOverride None
    Require all granted
</Directory>

如果系統啓用了SELINUX需要修改/repository安全上下文(可通過查看文件/etc/selinux/config或運行命令getenforce來判斷是否啓用了selinux)。

先看一下默認DocumentRoot的安全上下文:

# ls -dZ /var/www/html/
drwxr-xr-x. root root system_u:object_r:httpd_sys_content_t:s0 /var/www/html/

查看/repository安全上下文:

# ls -dZ /repository/
drwxr-xr-x. root root unconfined_u:object_r:default_t:s0 /repository/

default_t類型,httpd進程是不能訪問的,可以使用 chcon 或 restorecon 命令修改。修改/repository安全上下文類型:

# chcon -R -t httpd_sys_content_t /repository

使用chcon修改重啓系統後會失效,如要永久性修改上下文類型,使用 semanage fcontext 和 restorecon 命令:

# semanage fcontext -a -t httpd_sys_content_t "/repository(/.*)?"
# restorecon -R -v /repository

啓動apche:

# systemctl start httpd 
  1. 使用自己的Repository,創建repo文件

/etc/yum.repos.d/my.repo

[myextras]
name=CentOS-7 - Extras
baseurl=file:///repository/centos/7/extras/x86_64/
enabled=1
gpgcheck=0

[myextras]
name=CentOS-7 - Extras
baseurl=http://192.168.0.1/centos/7/extras/x86_64/
enabled=1
gpgcheck=0

Yum Repository詳解

資源站點

YUM
List of CentOS Mirrors
清華大學開源軟件鏡像站
華爲開源鏡像站
阿里巴巴開源鏡像站
EPEL Repository Mirrors
ELRepo Repository
Package search
RPM Search
RPM Find
一文徹底明白linux中的selinux到底是什麼
SELinux 環境下網絡服務設置 -- 配置 Apache、Samba、NFS

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