This is probably my longest standing action item in TERENA : implement a federated version of Confluence.

Below is the recipe for getting this to work with Ubuntu 12.04, Confluence 5.1, Apache, and modmellon.

I choose modmellon because it seemed like a cleaner solution than mod_shib, requiring no additional daemons and much simpler configuration.

The wiki will be open to the public, and logins will only be federated. New users will have their account automatically created, and are put in the confluence-users group.

Prerequisites

Before you start, make sure you have these bits:

A correctly configured apache web server that is able to serve an HTTPS web site (https://example.com).
A SAML Identity Provider (IdP).
An account on that IdP.
An attribute that can be used as username in Confluence (for example eduPersonPrincipalName). Attributes for full name and e-mail are optional but recommended.
The user name of the to-be administrator account. So, if you choose eduPersonPrincipalName as the attribute for username, you need to know your own value (for instance 'dvisser@surfnet.nl'.

PostgreSQL

apt-get install postgresql

Create a dedicated database user, and a database:

sudo su - postgres
createuser -S -d -r -P -E confuser
createdb -O confuser confluence

Confluence - part 1

This is a default install of Confluence, which has only local account and no federated logins - that comes later in part 2.

Install OpenJDK:

apt-get --no-install-recommends install openjdk-7-jdk

Download the source http://www.atlassian.com/software/confluence/downloads/binary/atlassian-confluence-5.1.tar.gz and unpack it to /opt/confluence. All relative paths mentioned below are relative to this directory.

Create a home directory for Confluence (/home/confluence).

Edit confluence/WEB-INF/classes/confluence-init.properties and configure confluence.home=/home/confluence.

Create the upstart script /etc/init/confluence:

# Upstart script for confluence
description     "Atlassian Confluence"
start on runlevel [2345]
stop on runlevel [!2345]
kill timeout 30
env RUN_AS_USER=root
env BASEDIR=/opt/confluence
script
    LOGFILE=$BASEDIR/logs/catalina.out
    exec su - $RUN_AS_USER -c "$BASEDIR/bin/catalina.sh run" >> $LOGFILE 2>&1
end script

Once this script is here, issue "start confluence" to get going, and watch the log file /opt/confluence/log/catalina.out. After some time you should see something like this:

INFO: Starting Coyote HTTP/1.1 on http-8090
Apr 09, 2013 5:14:43 PM org.apache.catalina.startup.Catalina start
INFO: Server startup in 65971 ms

By this time you can point your browser to http://example.com:8090, and it should come up with a configuration wizzard that will ask for a license key, database credentials, a local admin account, etc. Once that is all done, things should be working, but nothing federated yet, only local accounts.

At this point you need to do some preparation so that stuff will work properly later on through Apache:

Create a new admin account with the correct federated username. For instance, if you have decided on using eduPersonPrincipalName as the username, and the value of that attribute for your federated account is 'dvisser@surfnet.nl', create an account with that exactly that username. Obviously, Confluence username can
Make sure this newly created account is a member of "confluence-administrators".
Configure the Server Base Url to be the (HTTPS) URL that Apache will listen to. This is done in Confluence Admin -> General Configuration -> Edit.

Once this is complete, shut down Confluence by issuing "stop confluence".

Modmellon

Modmellon is an Apache module. To get this working I recompiled the Debian source packages from the University of Tilburg for Ubuntu 12.04 and made them available in our own APT repository.

Once that is done, the needed packages can be installed:

apt-get install libapache2-mod-auth-mellon
a2enmod auth_mellon

Create a directory /etc/apache/mellon, and store the Identity Provider metadata in XML format to a file called idp.xml.

Create the cryptographic material for the mellon SP:

openssl req -new -newkey rsa:2048 -days 3650 -nodes -x509 -keyout sp.key -out sp.crt

Now add this to the configuration of the vhost (note that this is not the entire config - you should have the HTTPS stuff etc already configured):

ServerName example.com
 
ProxyRequests Off
<Proxy http://localhost:8090>
        Order deny,allow
        Allow from all
</Proxy>


ProxyPass /mellon/ !
ProxyPass / http://localhost:8090/
ProxyPassReverse / http://localhost:8090/


# Mobile theme does not honour new seraph values, so we have to redirect that
RewriteEngine on
RewriteCond     %{QUERY_STRING} ^originalUrl=(.*)$      [NC]
Rewriterule     ^/plugins/servlet/mobile/login          /mellon/login?ReturnTo=%1 [R,NE]

<Location />
        MellonEnable "info"
        MellonSecureCookie On
        MellonSessionDump Off
        MellonSamlResponseDump Off
        MellonEndpointPath "/mellon"
        MellonSPPrivateKeyFile /etc/apache2/mellon/sp.key
        MellonSPCertFile /etc/apache2/mellon/sp.crt
        MellonIdPMetadataFile /etc/apache2/mellon/idp.xml

        # First unset to avoid security holes
        RequestHeader unset REMOTE_USER
        RequestHeader set REMOTE_USER "%{MELLON_username}e" env=MELLON_username

        RequestHeader unset FULLNAME
        RequestHeader set FULLNAME "%{MELLON_fullname}e" env=MELLON_fullname

        RequestHeader unset MAIL
        RequestHeader set MAIL "%{MELLON_email}e" env=MELLON_email
</Location>

By this time, you should be able to download the Service Provider metadata from https://example.com/mellon/metadata, and use it to add it to your IdP, thereby creating a trust relationship. Once that is done, you should be able to use federated authentication by going to https://example.com/mellon/login?ReturnTo=/

Confluence - part 2

Now everything is in place to federate Confluence. Make sure that Confluence isn't running any more.

Download the right version of remoteUserAuth.jar from https://github.com/chauth/confluence_http_authenticator/tree/master/releases, and store it in confluence/WEB-INF/lib
Download https://github.com/chauth/confluence_http_authenticator/blob/master/conf/remoteUserAuthenticator.properties and save it as confluence/WEB-INF/classes/remoteUserAuthenticator.properties. Edit it to suit your needs.

Edit confluence/WEB-INF/classes/serapth-config.xml and change this section in the beginning:

       <init-param>
            <param-name>login.url</param-name>
            <param-value>/login.action?os_destination=${originalurl}</param-value>
        </init-param>
        <init-param>
            <param-name>link.login.url</param-name>
            <param-value>/login.action</param-value>
        </init-param>

To this:

        <init-param>
            <param-name>login.url</param-name>
            <param-value>/mellon/login?ReturnTo=${originalurl}</param-value>
        </init-param>
        <init-param>
            <param-name>link.login.url</param-name>
            <param-value>/mellon/login?ReturnTo=%2Fdashboard.action</param-value>
        </init-param>