安装 epel-release 后，安装软件报错，解决办法

1、安装 epel-release

# yum install epel-release -y

2、执行 yum repolist 报错（部分主机会报错，大部分正常）

[root@Tang-1 ~]# yum repolist
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
Loading mirror speeds from cached hostfile
Loading mirror speeds from cached hostfile
Loading mirror speeds from cached hostfile
Loading mirror speeds from cached hostfile


 One of the configured repositories failed (Unknown),
 and yum doesn't have enough cached data to continue. At this point the only
 safe thing yum can do is fail. There are a few ways to work "fix" this:

     1. Contact the upstream for the repository and get them to fix the problem.

     2. Reconfigure the baseurl/etc. for the repository, to point to a working
        upstream. This is most often useful if you are using a newer
        distribution release than is supported by the repository (and the
        packages for the previous distribution release still work).

     3. Run the command with the repository temporarily disabled
            yum --disablerepo=<repoid> ...

     4. Disable the repository permanently, so yum won't use it by default. Yum
        will then just ignore the repository until you permanently enable it
        again or use --enablerepo for temporary usage:

            yum-config-manager --disable <repoid>
        or
            subscription-manager repos --disable=<repoid>

     5. Configure the failing repository to be skipped, if it is unavailable.
        Note that yum will try to contact the repo. when it runs most commands,
        so will have to try and fail each time (and thus. yum will be be much
        slower). If it is a very temporary problem though, this is often a nice
        compromise:

            yum-config-manager --save --setopt=<repoid>.skip_if_unavailable=true

Cannot retrieve metalink for repository: epel/x86_64. Please verify its path and try again

3、安装软件时，不依赖于 epel yum 仓库也会报错，如下：

[root@Tang-1 ~]# yum install tree
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
 * base: mirrors.huaweicloud.com
 * extras: mirror.jdcloud.com
 * updates: mirror.jdcloud.com
base                                                                                                          | 3.6 kB  00:00:00     
https://epel.mirror.constant.com//7/x86_64/repodata/repomd.xml: [Errno 14] curl#60 - "Peer's Certificate has expired."
Trying other mirror.
It was impossible to connect to the CentOS servers.
This could mean a connectivity issue in your environment, such as the requirement to configure a proxy,
or a transparent proxy that tampers with TLS security, or an incorrect system clock.
You can try to solve this issue by using the instructions on https://wiki.centos.org/yum-errors
If above article doesn't help to resolve this issue please use https://bugs.centos.org/.



 One of the configured repositories failed (epel repository),
 and yum doesn't have enough cached data to continue. At this point the only
 safe thing yum can do is fail. There are a few ways to work "fix" this:

     1. Contact the upstream for the repository and get them to fix the problem.

     2. Reconfigure the baseurl/etc. for the repository, to point to a working
        upstream. This is most often useful if you are using a newer
        distribution release than is supported by the repository (and the
        packages for the previous distribution release still work).

     3. Run the command with the repository temporarily disabled
            yum --disablerepo=epel ...

     4. Disable the repository permanently, so yum won't use it by default. Yum
        will then just ignore the repository until you permanently enable it
        again or use --enablerepo for temporary usage:

            yum-config-manager --disable epel
        or
            subscription-manager repos --disable=epel

     5. Configure the failing repository to be skipped, if it is unavailable.
        Note that yum will try to contact the repo. when it runs most commands,
        so will have to try and fail each time (and thus. yum will be be much
        slower). If it is a very temporary problem though, this is often a nice
        compromise:

            yum-config-manager --save --setopt=epel.skip_if_unavailable=true

failure: repodata/repomd.xml from epel: [Errno 256] No more mirrors to try.
https://epel.mirror.constant.com//7/x86_64/repodata/repomd.xml: [Errno 14] curl#60 - "Peer's Certificate has expired."

4、解决办法：替换 yum epel 源

4.1 删除原有 epel yum 仓库

[root@Tang-1 ~]# rm /etc/yum.repos.d/epel*
rm: remove regular file ‘/etc/yum.repos.d/epel.repo’? y
rm: remove regular file ‘/etc/yum.repos.d/epel-testing.repo’? y

4.2 创建新的yum epel 源

[root@Tang-1 ~]# wget -P /etc/yum.repos.d/ http://mirrors.aliyun.com/repo/epel-7.repo
--2014-01-01 13:50:16--  http://mirrors.aliyun.com/repo/epel-7.repo
Resolving mirrors.aliyun.com (mirrors.aliyun.com)... 61.182.131.228, 101.72.206.226, 101.72.206.227, ...
Connecting to mirrors.aliyun.com (mirrors.aliyun.com)|61.182.131.228|:80... connected.
HTTP request sent, awaiting response... 200 OK
Length: 664 [application/octet-stream]
Saving to: ‘/etc/yum.repos.d/epel-7.repo’

100%[===========================================================================================>] 664         --.-K/s   in 0s      

2014-01-01 13:50:16 (41.6 MB/s) - ‘/etc/yum.repos.d/epel-7.repo’ saved [664/664]

[root@Tang-1 ~]# yum repolist
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
 * base: mirror.jdcloud.com
 * extras: mirrors.huaweicloud.com
 * updates: mirrors.huaweicloud.com
base                                                                                                          | 3.6 kB  00:00:00     
epel                                                                                                          | 5.3 kB  00:00:00     
extras                                                                                                        | 2.9 kB  00:00:00     
updates                                                                                                       | 2.9 kB  00:00:00     
(1/3): epel/x86_64/group_gz                                                                                   |  88 kB  00:00:00     
(2/3): epel/x86_64/updateinfo                                                                                 | 1.0 MB  00:00:00     
(3/3): epel/x86_64/primary_db                                                                                 | 6.9 MB  00:00:07     
repo id                                         repo name                                                                      status
base/7/x86_64                                   CentOS-7 - Base                                                                10,097
epel/x86_64                                     Extra Packages for Enterprise Linux 7 - x86_64                                 13,416
extras/7/x86_64                                 CentOS-7 - Extras                                                                 304
updates/7/x86_64                                CentOS-7 - Updates                                                                332
repolist: 24,149

5、可以正常安装软件

[root@Tang-1 ~]# yum install nginx -y
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
 * base: mirror.jdcloud.com
 * extras: mirrors.huaweicloud.com
 * updates: mirrors.huaweicloud.com
base                                                                                                          | 3.6 kB  00:00:00     
epel                                                                                                          | 5.3 kB  00:00:00     
extras                                                                                                        | 2.9 kB  00:00:00     
updates                                                                                                       | 2.9 kB  00:00:00     
Resolving Dependencies
--> Running transaction check
---> Package nginx.x86_64 1:1.12.2-3.el7 will be installed
--> Processing Dependency: nginx-all-modules = 1:1.12.2-3.el7 for package: 1:nginx-1.12.2-3.el7.x86_64
--> Processing Dependency: nginx-filesystem = 1:1.12.2-3.el7 for package: 1:nginx-1.12.2-3.el7.x86_64
--> Processing Dependency: nginx-filesystem for package: 1:nginx-1.12.2-3.el7.x86_64
--> Processing Dependency: libprofiler.so.0()(64bit) for package: 1:nginx-1.12.2-3.el7.x86_64
--> Running transaction check
---> Package gperftools-libs.x86_64 0:2.6.1-1.el7 will be installed
---> Package nginx-all-modules.noarch 1:1.12.2-3.el7 will be installed
--> Processing Dependency: nginx-mod-http-geoip = 1:1.12.2-3.el7 for package: 1:nginx-all-modules-1.12.2-3.el7.noarch