mpv/DOCS/tech/mirrors/mirror_howto.txt

                          ------------------------------
                          How to build an MPlayer mirror
                          ------------------------------

This document might be inacurate or even incomplete, please
send feedback + corrections to the mplayer-mirror mailing list.

About this document
~~~~~~~~~~~~~~~~~~~

Mirroring MPlayer is quite easy but requires a few steps to be taken
and a few things taken care of. This document describes these steps
in detail so that anyone wishing to build an official or an unofficial
mirror can do that without much trouble.


A note on performance issues
~~~~~~~~~~~~~~~~~~~~~~~~~~~~

A few of the commands used here will generate some load on our main server.
Too many clients executing them at once will overload our server and cause
a performance degradation for all our users. Thus we kindly ask you to be
considerate about what you do. We do not want to restrict mirroring to a
few select people, but this requires everyone using the system described
here to behave.


Outline of the mirroring system
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The mirroring system uses rsync to transfer the data and to perform
updates. A script (update_mplayer_rsync) is provided to call the rsync
client with the right set of parameters. This script should be run
periodically via cron.
Additionally, official mirrors should set up an ssh account so that
updates can be triggered when important changes on the main server
are performed.
Mirrors should provide their data over HTTP or FTP or both. Each official
mirror will be assigned a mirror number (wwwXXX.mplayerhq.hu or
ftpXXX.mplayerhq.hu where XXX is the mirror number). This mirror
number determines the hostname over which it can be reached directly.

All mirrors are put into our DNS round-robin for the www.mplayerhq.hu and
ftp.mplayerhq.hu names and should be set up to respond to these names as well.


Requirements
~~~~~~~~~~~~
The requirements for any (official) mirror are:
1) rsync installed and some way to run the sync script periodicaly (eg cron)
2) subscribing to the mplayer-mirror mailing list (see below)

The requirements for a full website mirror are:
1) 500MB of free disk space (for the ftp and homepage directories).
2) A network connection with about 5Mbit/s sustained bandwidth.
3) A simple webserver that allows redirections and virtual server,
   no PHP or CGI needed as all pages are static.

The requirements for a full ftp mirror are:
1) 500MB of free disk space (for the ftp directory).
2) (No bandwidth data for a ftp only server available)


Getting the data, mirroring script and cron setup
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The mirroring script is located in our Subversion repository at

  svn://svn.mplayerhq.hu/mplayer/trunk/DOCS/tech/mirrors/update_mplayer_rsync

or on the web at

  http://svn.mplayerhq.hu/*checkout*/mplayer/trunk/DOCS/tech/mirrors/update_mplayer_rsync

This script requires a working `rsync` client. The handling of the
lock file is done by using `lockfile` from the procmail package.
Using a lock file is recommended but not necessary. The temporary file
generation is handled by `mktemp` which is available from
http://www.mktemp.org/mktemp/ .

The script contains a few configuration variables at the beginning that
can and should be set:
PATH: The $PATH to be used within the script (recommended).
LOCK: The full path to the lock file to be used (/var/lock/mplayer-mirror-lock
      or something similar, recommended).
MIRROR_ROOT: The root of the mirror. This is the directory where all files
             are downloaded to (required).
MAILADR: The mail address where reports should be sent to (required).
TMPDIR: The directory where temporary files should be created.
        If you set this explicitly, you have to uncomment the export below
        (defaults to /tmp if not set).

Install this script and set the variables according to your setup. Then run
it once to get the first checkout of the mirror. This will require (at the
time of this writing - 2006-06) about 500MB of disk space.
You should get two directories in your $MIRROR_ROOT: homepage and MPlayer.
The former containing the HTML pages for the mirror and the latter the
downloadable files.

If this worked out OK, you should set up a cron job that periodically updates
the files. If you run an official mirror you should run the script every
6h to 12h (6h recommended). If you do not run an official mirror, you should
not run the script more often than once a day. Please use an "odd" time
to run the script when it is unlikely that any other cron job is running.
Bad times are e.g. full hours, or minutes that are divisible by 5.
An example crontab line would look like this:
---
17 1,8,13,19 * * * /path/to/update_mplayer_rsync
---
(please change the minute and hours to something random)

You can change the rest of the script as you see fit, although it is not
recommended. Please DO NOT CHANGE the options of the rsync commands.
Especially DO NOT REMOVE the -t and -W options. These prevent calculating
checksums on the server side which are very expensive.


Setting up an SSH account for update triggers
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Official mirrors should provide an ssh-based trigger to run the update script
on request. This makes it possible to distribute releases and other important
files immediately to all mirrors.

The setup does not need a special user other than the one as which the update
script is run and does not allow running any other command.

First you need to create an ssh key pair by running:
---
ssh-keygen -t dsa -C MPHQ_rsync_trigger -f www#_sshkey
---
(replace the '#' by your mirror number)

You should send the private key to us by mail and specify the host and
user to be used. Please use a private mail of one of the admins and
DO NOT send the private key to the mirror mailing list.

The public key should be placed in the ~/.ssh/authorized_keys file of the
user running the updates. To restrict the ssh key to only one command place
the following directives at the beginning of the line with the key:
from="*.mplayerhq.hu",command="<path_to_update_mplayer_rsync>"
e.g.:
---
from="*.mplayerhq.hu",command="/path/to/update_mplayer_rsync" ssh-dss AAAA
B3NzaC1kc3MAAAEBAI20yhE3/bRjzojUhhMz4DHnGhcJUiPWOfoP9CygnFOYOxJTFlxgqM3iJiHWRxgK
FJ/Uw40eV9K4Ww4fp2pe1guXJzKna8+6vBXaPPVEVxSyaxgtt4Xt3zpUuCnNljgArcEhwcNyOyH2RVln
yhyxsrKhuq5ZoNHD3caBGjZu3eOR2atPGS1NOdeN/hytIoh8T8DicPqPI29yWX9yAjnHv6wdPutwMLu6
[...]
n0Fs3CJY6/1UpgDGH7VPey0SdpJEDewltRLA+buP++2vJD/NUOeGzcRydo2NdZ1wiiaytXxkaec928JC
NABTeBh6NKAg4vnPvcRLKEBVdSrar/fARSbOmf3HOcsw3uZoAIE9jDGhnMKcnXfHjPZ2tZP9CHs6Wo4n
yDOxIfDZmJ7VJqMRc6//p5k81pkkGvawbPA63StI/Dkv/648l4XONuJc2z5gaUdjrTA8TsD/VJGiGcHl
mlGj3IWCBz7e4+XB3L64kFZwLCYN8kwDUAaHq4EtcMVOnQ== MPHQ_rsync_trigger
---
(lines split for readability)


Setting up a webserver
~~~~~~~~~~~~~~~~~~~~~~

Set up Apache or whatever web server you prefer. We just have static pages,
so no fancy configuration is necessary. However, we need a few aliases so that
links on our pages work correctly. /MPlayer and /DOCS should redirect to the
directory with the downloadable files.

Here is an example stanza to paste into your Apache configuration:

<VirtualHost www#.mplayerhq.hu>
        DocumentRoot /path/to/htdocs
        Options FollowSymLinks Indexes
        Alias /MPlayer  /path/to/MPlayer
        Alias /DOCS     /path/to/MPlayer/DOCS
        AddDefaultCharset off
</VirtualHost>

<VirtualHost www.mplayerhq.hu>
        DocumentRoot /path/to/htdocs
        Options FollowSymLinks Indexes
        Alias /MPlayer  /path/to/MPlayer
        Alias /DOCS     /path/to/MPlayer/DOCS
        AddDefaultCharset off
</VirtualHost>

The AddDefaultCharset directive is necessary because newer versions of Apache
appear to default to defining a standard charset. This breaks our documentation
translations, which are written in different encodings.

The second VirtualHost is necessary for the DNS round-robin address.
To check whether this VirtualHost works, you can add a temporary entry into
your /etc/hosts file:

1.2.3.4 www.mplayerhq.hu

Replace the IP address by the real IP address of your mirror. Do not forget to
remove the entry after you finish testing.


Webserver checklist
~~~~~~~~~~~~~~~~~~~

After setting up the web server, please verify that the following things work
both for your mirror address (www#.mplayerhq.hu) and the DNS round-robin
address (www.mplayerhq.hu):

- The virtual host is reachable by its address.
- The MPlayer and DOCS subdirectories work.
- The man pages and documentation are served with the correct content-type.
  Try Russian or Chinese, you will notice breakage immediately.


Setting up an FTP server
~~~~~~~~~~~~~~~~~~~~~~~~

Any FTP server will do. We use vsftpd, it is fast and secure. The setup is
similar to the web server setup. The FTP server should listen on both its mirror
address (ftp#.mplayerhq.hu) and the DNS round-robin address (ftp.mplayerhq.hu).
All our mirrors are public, so you should allow anonymous access.

You should have the same directory layout as we do on our server, so there
should be a subdirectory named 'MPlayer' (notice the capitals) that contains
the downloadable files.


Mailing list
~~~~~~~~~~~~

All official mirror admins are required to subscribe to the mplayer-mirror
mailing list. It's used to coordinate the efforts and distribute information
among all admins. It is also very low traffic. Please use the webinterface
on http://lists.mplayerhq.hu/mailman/listinfo/mplayer-mirror to subscribe.
Please do not top-post on this mailing list.