Infrastructure/Mirroring/zh-cn

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Fedora 项目在全球拥有超过 200 个志愿镜像站点 点击查看 ,这有助于分发 Fedora 。我们十分感谢他们!

Contents

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镜像大约有多大?

请仔细阅读。

出口原则

By downloading Fedora software, you acknowledge that you understand all of the following: Fedora software and technical information may be subject to the U.S. Export Administration Regulations (the “EAR”) and other U.S. and foreign laws and may not be exported, re-exported or transferred (a) to any country listed in Country Group E:1 in Supplement No. 1 to part 740 of the EAR (currently, Cuba, Iran, North Korea, Sudan & Syria); (b) to any prohibited destination or to any end user who has been prohibited from participating in U.S. export transactions by any federal agency of the U.S. government; or (c) for use in connection with the design, development or production of nuclear, chemical or biological weapons, or rocket systems, space launch vehicles, or sounding rockets, or unmanned air vehicle systems. You may not download Fedora software or technical information if you are located in one of these countries or otherwise subject to these restrictions. You may not provide Fedora software or technical information to individuals or entities located in one of these countries or otherwise subject to these restrictions. You are also responsible for compliance with foreign law requirements applicable to the import, export and use of Fedora software and technical information.

如何搭建一个公共镜像?

搭建公共镜像非常简单,而且将越来越容易。确保您的网站拥有足够的带宽和磁盘空间来承担负载,这就是我们的全部要求。每个 Fedora 发行版都会消耗200GB以上的磁盘空间,并且有可能下载者会耗尽您的全部带宽。镜像站点应至少有100Mbps的带宽连接到互联网,现有许多站点是基于千兆或更高的带宽工作的。以 Fedora 8 发行版为例,其在主服务器上消耗的总空间(也是镜像站点要消耗的空间)达到了1.1TB并且仍在增长。1-2TB的空间适合于建立长期镜像。这是基于硬链接的空间概念,如果您不能使用硬链接(例如,使用AFS),您将需要更多的磁盘空间。实际磁盘空间消耗在该文件中已给出:

http://dl.fedoraproject.org/pub/DIRECTORY_SIZES.txt

如何搭建一个私有镜像?

私有镜像是那些只能被内部人员访问的某些组织或者机构专有的镜像,例如公司,学校等等。这些镜像是为了在机构内部加快 Fedora 的分发而被开设的。当然,这些镜像所处的网络对当地的带宽消耗远少于连接互联网的。

私有镜像运行与公共镜像基本无异,除了以下几点:

  • 镜像管理器的 publiclist 不会有该镜像的显示。
  • 无法从本社区镜像获取同步文件,只能寻求其他公共镜像。
  • Private mirrors should include IP netblocks in their MirrorManager configuration. This allows your network-local users to be automatically redirected to your mirror. You may list IP netblocks (e.g. 18.0.0.0/8), or if your network is NAT'd, the hostname of your NAT gateway.
  • 私有镜像不会被镜像管理器的蜘蛛爬行。
  • Private mirrors must run report_mirror to inform the MirrorManager database of their content. If you don't run report_mirror, your clients will not be automatically redirected.

You may also find it more beneficial to run an IntelligentMirror instead of a full rsync mirror. In this way, only the updates your local users actually need will be cached on your local mirror, saving you the bandwidth from downloading updates you don't actually need.

镜像管理器:Fedora 项目的镜像管理系统

镜像管理器跟踪所有的镜像而不需要很多的人工的文件编辑。镜像站点的管理员一点要确保 report_mirror 脚本和 mirrormanager-client 在每次 rsync 之后被运行以更新镜像管理数据库。

注册

Fedora 账户系统

  • 您必须有一个 Fedora 账户。 不过您不必为了镜像内容而去签署Contributors License Agreement,但是如果您想要在其他领域做贡献,您必须签署。
  • 如果是公共镜像,您必须要发送一封邮件至 mirror-admin@fedoraproject.org 来介绍一下您的镜像。同时这也是您想成为公共镜像的声明。注意这封邮件必须涵盖了您的镜像的 IP 地址,所处国家或地区以及该镜像的流量和带宽。

如果是私有镜像则不必了,如果您想介绍一下自己,请简短。

在 MirrorManager 中注册

  • 使用您的 FAS 账户登录 mirrormanager
  • 点击 [Add Site] 创建一个新站点;
  • create a new Host, and sign up that host for the Categories of content you'll carry, any other site administrators you want, your site's IP addresses used for our Access Control List, and the other details listed there if applicable to you
  • 请在每次同步完成后运行 report_mirror
  • 您可以列出您的镜像的 IP 段(IP 地址范围)。从您的 IP 段内来访的请求会自动跳转至您的镜像。
  • You may list your site's BGP Autonomous System Number (ASN). Clients on your ASN will be automatically redirected to your mirror for any content you carry. One way to lookup up your ASN is to query it from the routeviews.org DNS servers. It is like a PTR record lookup, but at a specific server.例如,想要查找143.166.1.1,输入:
$ dig txt 1.1.166.143.asn.routeviews.org @archive.routeviews.org
;; ANSWER SECTION:
1.1.166.143.asn.routeviews.org.	86400 IN TXT	"3614" "143.166.0.0" "16"

响应的就是 TXT 记录,3614。

搭建

最简单的做法,也是最通用的,就是用 rsync 工具来同步。注意该工具的 -H (硬链接), --delay-updates--numeric-ids--delete-after 选项是必须要启用的。示例:

rsync -vaH --exclude-from=${EXCLUDES} --numeric-ids --delete --delete-after --delay-updates \
 rsync://dl.fedoraproject.org/fedora-enchilada ${LOCAL_DIR}
  • 要同步的内容由您决定,不必同步所有内容,比如某些特殊架构的专用版您可以选择性同步。
  • 请从1级镜像站点同步。请见 Infrastructure/Mirroring/Tiering。除了以上方法,您也可以选择从一个比较快的镜像同步。请联系相关站点管理员以便将您的站点添加到他们的访问控制列表中。
  • 您应该在08:00 UTC(此时是 rawhide 版本发布)后同步, 14:00 UTC (when bitflips occur), 且一天同步次数为3-5次。
  • 你应该设置您的站点同步时间为一个随机值以便拉平上游镜像的负载。最好写一个cron job:
 45 */6 * * * perl -le 'sleep rand 1800' && bash -l ~/mirror-fedora > /dev/null
  • 如果您使用 rsync 3.0以上版本,您可以使用 --delete-delay 选项替换 --delete-after,这种情况下可以提高性能。具体资料请见:这份报告

运行 report_mirror

镜像管理器包含了一个工具 report_mirror ,该工具可以在您完成同步任务后通报官方您的镜像本次同步的详细信息。这对我们的日常管理和用户的安装很有帮助。请在每次同步完成后运行 report_mirror。请通过以下方法安装获取:

yum install mirrormanager-client

或者访问 report_mirror files获取代码。您也可以使用 git 来获取:

git clone git://git.fedorahosted.org/git/mirrormanager
  或者
git clone http://git.fedorahosted.org/git/mirrormanager/ 


您需要 report_mirror 和 report_mirror.conf,且必须配置 report_mirror.conf 以便识别您的磁盘上所有镜像文件位置。

可用内容

请要注意同步的内容:

建议的同步的部分
rsync module Description path on master server Comments
fedora-enchilada0 Fedora - the whole enchilada /pub/fedora Please use this if you can, it provides the all current Fedora content, including pre-bitflip content. This is open to specific mirrors by request. Mirrors participating in our tiering should use this.
fedora-epel0 Extra Packages for Enterprise Linux /pub/epel Please use this to mirror EPEL
fedora-archive Historical Fedora releases /pub/archive Fedora Core 1-6 and Extras 3-6, and obsolete releases 7 and higher
fedora-secondary Fedora Secondary Arches /pub/fedora-secondary
fedora-alt Fedora Other /pub/alt


以下内容请不要同步,它们是特定时期的产物。

同步的目录 描述 path on master server 备注
fedora-enchilada Fedora - the whole enchilada /pub/fedora Please use this if you can, it provides the all Fedora content except pre-bitflip content. This is open for the general public to use.
fedora-linux-releases Fedora Linux Releases /pub/fedora/linux/releases
fedora-linux-development Fedora Linux Development (Rawhide) /pub/fedora/linux/development
fedora-linux-updates Fedora Linux Updates /pub/fedora/linux/updates
fedora-epel Extra Packages for Enterprise Linux /pub/epel EPEL doesn't do the bitflip trick, so this is the same as fedora-epel0 above.
Red Hat Enterprise Linux Beta

RHEL beta 版本也通过 MirrorManager 分发。Fedora 项目的一级镜像可以同步这些内容。

同步的目录 描述 path on master server 备注
rhel-beta RHEL /pub/redhat on rhm3.redhat.com

DVD,CD 和 exploded trees

When a new release is available, it can be bandwidth-efficient to download only the ISOs first (say, the DVD ISOs), then explode those into the directory structure, then run a full normal rsync run. This lets you avoid downloading the same RPMs twice (both on ISOs and as plain RPMs). There's a tool somewhere to help do this.

Regular hardlink runs

While the Fedora release maintainers try to keep as little redundant packaging around as possible, there are some duplicate packages in the tree. For example, when a Fedora Test release comes out, the package set included there looks remarkably like that of the development tree from a few days before. By copying the development tree over into the new Test directory before starting your rsync run, and using rsync -H, you can avoid downloading all that content a second time.

In addition, it's good practice to run a tool like hardlink++ on your tree occasionally (say, weekly), to ensure as much of your tree as possible is hardlinked.

Pre-Release: Copying Development tree to new release directory

In the days leading up to a release, either test or final, the development tree will stop taking new packages, and will closely resemble what winds up in the new release. As a mirror, you can avoid downloading content that already is in your copy of the development tree that matches what's in the release tree by copying those packages using hardlinks, such as:

cp -lr fedora/linux/development/13/i386/os fedora/linux/releases/13/Fedora/i386/
cp -lr fedora/linux/development/13/x86_64/os fedora/linux/releases/13/Fedora/x86_64/
cp -lr fedora/linux/development/13/source fedora/linux/releases/13/Fedora/

and then start the rsync process, which will clean up any changes and fix up the timestamps.

Rsync Configuration (sample)

Larger mirrors, like kernel.org, have slightly custom front-ends to rsync (mainly so that they can have a single rsync instance and have multiple ip based vhost configuration files) That said what follows is a sample rsync configuration file for public syncing (this is not intended for private pre-bitflip mirroring)

[fedora]
        comment         = Fedora - RedHat community project
        path            = <path to your fedora directory>
        exclude         = lost+found/
        read only       = true
        max connections = 100
        lock file       = /var/run/rsyncd-mirrors.lock
        uid             = <user id (numeric, or textual) of an anonymous style user who should have read access>
        gid             = <group id (numeric, or textual) of an anonymous style user who should have read access>
        transfer logging = yes
        timeout         = 900
        ignore nonreadable = yes
        dont compress   = *.gz *.tgz *.zip *.z *.Z *.rpm *.deb *.bz2
        refuse options = checksum

Things to explicitly note:

  • The path above should be a full path to your fedora directory
  • You should *really* want to leave this read-only
  • Make sure your uid/gid are set to public users, not to the user that you run as your sync agent. If you set this to the user who does your syncs you will be inadvertently giving the public full pre-bitflip access.
  • Make sure you have the 'refuse options' set to checksum, your server will be *MUCH* happier with this set, as it will prevent public users from performing a checksum run against you. This can be incredibly I/O abusive, so should not be available to the general public.

HTTPd 配置

Keepalives

HTTP Keepalives should be enabled on your mirror server to speed up client downloads. By default, Fedora's Apache httpd package has keepalives disabled. They should be enabled, with a timeout of at least 2 seconds (the default of 15 seconds might be too high for a heavily loaded mirror server, but 2 seconds is sufficient and appropriate for yum).

KeepAlive On
KeepAliveTimeout 2
MaxKeepAliveRequests 100

Other http servers such as lighttpd have keepalives enabled by default.

Caching of metadata

We don't want caching proxy servers between our mirrors and our end user systems to cache our yum repository metadata. So, add explicit metadata handling. (Suggested by the OpenSUSE download redirector.)

   <LocationMatch "\.(xml|xml\.gz|xml\.asc|sqlite)$">
       Header set Cache-Control "must-revalidate"
       ExpiresActive On
       ExpiresDefault "now"
   </LocationMatch>
Redirecting ISO downloads to FTP

While no longer a recommended practice, the following mod_rewrite rules will force all *.iso files to be downloaded via FTP. In this example HEAD requests are not redirected, so the MirrorManager crawler is not disrupted.

RewriteCond     %{REQUEST_METHOD} GET
RewriteRule     ^(.*\.iso)$ ftp://myserver/$1  [L,R=301] 
Content Types

ISO and RPM files should be served using MIME Content-Type: application/octet-stream. In Apache, this can be done inside a VirtualHost or similar section:

<VirtualHost *:80>
AddType application/octet-stream .iso
AddType application/octet-stream .rpm
</VirtualHost>
Limiting Download Accelerators

Download accelerators will try to open the same file many times, and request chunks, hoping to download them in parallel. This can overload heavily loaded mirror servers, especially on release day. Here are some tricks to thwart such activities.

To limit connections to ISO dirs by some amount per IP:

<IfModule mod_limitipconn.c>
MaxConnPerIP 6
</IfModule>

To block ranged requests as this is what download accelerators do indeed:

RewriteEngine on
RewriteCond %{HTTP:Range} [0-9] $
RewriteRule \.iso$ / [F,L] 

Similar things can be done with iptables and the recent module, which might give you a little more ability to control what is being done, either by limiting new connections or by dropping 50% of a users packets.

Logging Partial Content Downloads

Partial content can be logged correctly using apache:

# this includes actual counts of actual bytes received (%I) and
# sent (%O); this requires the mod_logio module to be loaded.

LogFormat "%h %l %u %t \"%r\" %>s %b \"%{Referer}i\" %I %O \"%{User-Agent}i\"" combined

Pre-bitflip mirroring

Several days before each public release, the content will be staged to the master mirror servers, but with restricted permissions on the directories (generally mode 0750), specifically, not world readable.

Mirror servers should have several different user/group accounts on their server, for running the different public services. Typically you find:

  • HTTP server runs as user apache, group apache
  • FTP server runs as user ftp, group ftp
  • RSYNC server runs as user rsync, group rsync
  • a user account for downloading content from the masters (e.g. user mirror, group mirror).

The user account used to download content from the masters must be not be the same as the HTTP, FTP, or RSYNC server accounts. This guarantees that content downloaded with permissions 0750 will not be made available via your public servers yet.

On the morning of the public release, the permissions on the directories on the master servers will change to 0755 - world readable. This is called the bitflip.

Mirrors may either rsync one more time to pick up these new permissions (but won't have to download all the data again), or preferably, can schedule a batch job to bitflip:

$ echo "chmod a+rx /pub/fedora/linux/releases/9" | at '14:45 UTC May 13 2008'
Serving content to other mirrors

Tier 1 mirrors will necessarily need to share content to Tier 2 mirrors before the bitflip. This is done by running another instance of the rsync daemon, on a different port (e.g. 874), with an Access Control List to prevent public downloads, running as a user in the same group as downloaded the content (e.g. group mirror). This could be user mirror, group mirror, who has group read/execute permissions on the still-private content.

Tier 1 mirrors have a tendency to use different authentication methods for granting access to these non-public downloads, they vary from maintaining IP based ACL's to assigning username/password combinations to mirrors wishing to sync from them. Each method has advantages / disadvantages, the IP list is 'simpler' from a mirrormanager perspective as mirrormanager can give you the list of IP's but from an automation standpoint can be more difficult (as rsync's configuration file does not allow that ACL list to be stored in a separate file). Username / passwords can be more versatile as sites mirroring can change IPs without notifying you, but it's easier for those credentials to leak out and get miss-used.

全球镜像分布地图

mirrors.png

每日更新。如果没有显示请稍后再试。

感谢

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