A release download page is the page that links the project's content to the mirrored artifact download. This document aims to describe the various options available to projects for download pages together with policy and best practices. (Background about the policy is in a separate document.) Release managers are the target audience.

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Download Links

  • All links to the mirrored distribution artifacts must not reference the main Apache web site. They should use the standard mechanisms to distribute the load between the mirrors.

  • All links to checksums, detached signatures and public keys must reference the main Apache web site and should use https:// (SSL).

  • Old releases should be archived and may be linked from the download page.

  • Artifacts which are not full official releases (for example, milestones, betas and alphas) may be linked from the download page. Links to these artifacts should be removed in a timely fashion.

Download Scripts

Balancing the downloads between mirrors requires the use of a script. A standard mechanism has been created that allows scripts to be easily created which will not only comply with mirroring distribution policy but also take advantage of more advanced features such as intelligent selection of a preferred mirror. This mechanism is described below.

There are two basic options available:

  • The generic download script is quick to setup but is linked from (rather than integrated with) the project documentation.

  • A project specific script which is integrated with a page created in the normal way for the project and which uses the project's standard document look and feel. This option takes more time to setup.

Standard Generic Download Script

The starting point for a generic script is a download page. This is just a page in the standard documentation which describes the releases. To use the generic script, this page needs to be altered so that the actual download links to the generic script in the appropriate fashion.

The generic script is called closer.cgi. The relative path of the distribution (from the distribution root to the artifact) needs to be passed in as a parameter. So (for example) if the artifact is foo-5.5.1.zip and is located in bar/foo relative to /www/www.apache.org/dist then http://www.apache.org/dyn/closer.cgi/bar/foo/foo-5.5.1.zip will display the mirrored distribution for download.

Note there is some information which every project should include on the download page. Please read best practices.

Project Specific Download Script

To create a project specific download page, two elements are needed:

  • a wrapper cgi script (for the standard python mirroring script)

  • a project page (containing information to be presented to the user together with variables to be replaced by the script)

The script takes the path to the project page as an input and passes this to the standard mirroring script. The standard script then reads the page and uses information about the mirrors to substitute values for the varibles. When linking to the project page (for example, from the rest of the project documentation), it is important that these links are targeted at the script address (and not the page address).

Conventionally, the wrapping script is called download.cgi. This should be created in the same directory as the project page. This wrapper script just needs to set up the correct directory and call the mirroring script. The following will do:

#!/bin/sh
# Wrapper around the standard mirrors.cgi script
exec /www/www.apache.org/dyn/mirrors/mirrors.cgi $*

The release download page should be generated in the same way as the rest of the project documentation. By convention, the name of the output should be download.html.

Note: the mirroring script guesses the download release page to be processed by matching file names. There is no requirement to call the script download.cgi and the download release page download.html but the name of the script must correspond to the name of the download page. For example, release.cgi and release.html will work but download.cgi and release.html will not.

There are a number of elements that a good project download page should contain. The content used to generate that page can be viewed here.

Downloads of artifacts linked to a mirror by an variable url. The correct mirroring base url will be substituted for the [preferred] variable. The rest of the url should be the path to the artifact relative to the base of the Apache distribution directory.

For example, for artifact foo-1.0.0.tar.gz contained in bar/foo should use [preferred]/bar/foo/foo-1.0.0.tar.gz

Links to the checksum and signature for the artifact should be given next to the download link. It is important that users check the sum and verify the signature so these links should be close and clear. Note: these documents must not be mirrored.

For example, for artifact foo-1.0.0.tar.gz contained in bar/foo :

<a href="[preferred]/bar/foo/foo-1.0.0.tar.gz">zip</a>
<a href='http://www.apache.org/dist/bar/foo/foo-1.0.0.tar.gz.md5'>MD5</a>
<a href='http://www.apache.org/dist/bar/foo/foo-1.0.0.tar.gz.asc'>PGP</a>

Users should also be given information about the mirrors and the chance to choose a different mirror (if they prefer). This is a little complex to describe so here is a typical script:

<p>[if-any logo]
<a href="[link]"><img align="right" src="[logo]" border="0"
/></a>[end]
The currently selected mirror is <b>[preferred]</b>.  If you
encounter a
problem with this mirror, please select another mirror.  If all
mirrors are failing, there are <i>backup</i> mirrors (at the
end of
the mirrors list) that should be available.</p>

<form action="[location]" method="get" id="SelectMirror"> Other mirrors: <select name="Preferred"> [if-any http] [for http]<option value="[http]">[http]</option>[end] [end]
[if-any ftp] [for ftp]<option value="[ftp]">[ftp]</option>[end] [end] [if-any backup] [for backup]<option value="[backup]">[backup] (backup)</option>[end] [end] </select> <input type="submit" value="Change" /> </form>

<p>You may also consult the <a href="http://www.apache.org/mirrors/">complete list of mirrors</a>.</p>

More advice on creating a good project page is given below

Once the download page and the script have been uploaded to the project website (in the usual manner), make the script executable. For example:

% svn propset svn:executable yes download.cgi
% svn commit
All that remains is to wait for the main website to sync.

Remind Users To Check Sums And Signatures

Apache releases are downloaded from mirrors. It is therefore important that users understand that they should always check the md5 sums and (if possible) also verify the OpenPGP compatible signature. The content of the release download page plays a critical role in this education process.

Please provide clear and easy links to the KEYS, sums and signatures from the download release page or include the information directly in the page itself. This page is a good example.

Include a reminder text with links to more information for users. For example:

Note: when downloading from a mirror please check the md5sum and verify the OpenPGP compatible signature from the main Apache site. Links are provided above (next to the release download link). This KEYS file contains the public keys used for signing release. It is recommended that (when possible) a web of trust is used to confirm the identity of these keys. For more information, please see the Apache Release FAQ.

Ensure Browser Displays Linked URL

Users need to understand the origin of the artifacts, signatures and sums downloaded. Check that the stylesheets used do not obscure the linked url. It is best to use a simple, plain style for download links. Note that some of the maven style sheets may obscure some external links in some browsers (in particular MSIE).

Support for bypassing the 24 hour rule

Normally you should wait 24 hours after uploading a release to http://www.apache.org/dist/ before announcing it, in order to let mirrors catch up.

If you are unable to wait 24 hours before announcing your release, then you can pass a date and time to the download script to indicate that only mirrors that have updated since that time should be selected. This works by adding update=YYYYMMDDhhmm to the query string. For example, you can use http://httpd.apache.org/download.cgi?update=200407051415 to request only mirrors that have updated after 2:15pm on July 5, 2004 UTC. Please use this option sparingly, since it can result in excessive load on particular mirrors. It would be appropriate, for example, in an emailed release announcement for an important security release, but should not usually be used as a main website link.

Resources

Read these instructions thoroughly before configuring your project mirror. See also the excellent mirroring, PGP and MD5 resources by Henk. Review how other ASF projects do their mirrors.

Questions?

If you need assistance in implementing URL redirection to direct downloaders to the mirrors, or if you need any other help in implementing this policy, please contact the infrastructure@apache.org mailing list.