Difference between revisions of "Hudson-ci/Running Hudson behind Apache"

Latest revision as of 12:14, 18 August 2011

	Running Hudson behind Apache

Introduction

In situations where you have existing web sites on your server, you may find it useful to run Hudson (or the servlet container that Hudson runs in) behind Apache, so that you can bind Hudson to the part of a bigger website that you may have. This document discusses some of the approaches for doing this.

Make sure that you change the Hudson httpListenAddress from its default of 0.0.0.0 to 127.0.0.1 or any Apache-level restrictions can be easily bypassed by hitting the Hudson port directly.

mod_proxy

mod_proxy works by making Apache perform "reverse proxy". — When a request arrives for certain URLs, Apache becomes a proxy and further forward that request to Hudson, then it forwards the response back to the client.

The following Apache modules must be installed :

• a2enmod proxy
• a2enmod proxy_http

A typical set up for mod_proxy would look like this:

ProxyPass         /hudson  http://localhost:8081/hudson
ProxyPassReverse  /hudson  http://localhost:8081/hudson 
ProxyRequests     Off

1. Local reverse proxy authorization override
2. Most unix distribution deny proxy by default (ie /etc/apache2/mods-enabled/proxy.conf in Ubuntu)

<Proxy http://localhost:8081/hudson*>
  Order deny,allow
  Allow from all
</Proxy>

This assumes that you run Hudson on port 8081. {(note|For this set up to work, the context path of Hudson must be the same between your Apache and Hudson (that is, you can't run Hudson on http://localhost:8081/ci and have it exposed at http://localhost:80/hudson).

Set the context path in Windows by modifying the hudson.xml configuration file and adding {code|--prefix=/hudson} (or similar) to the <arguments> entry.}}

The _ProxyRequests Off_ prevents Apache from functioning as a forward proxy server (except for _ProxyPass_), it is advised to include it unless the server should function as a proxy. If you are running Apache on a Security-Enhanced Linux (SE-Linux) machine it is essential to make SE-Linux do the right thing by issuing as root

setsebool -P httpd_can_network_connect true

If this is not issued Apache will not be allowed to forward proxy requests to Hudson and only an error message will be displayed.

Because hudson already compress its output, you can not use the normal proxy-html filter to modify urls:

SetOutputFilter proxy-html

Instead you can use the following:

SetOutputFilter INFLATE;proxy-html;DEFLATE
ProxyHTMLURLMap http://your_server:8080/hudson /hudson

See http://wiki.uniformserver.com/index.php/Reverse_Proxy_Server_2:_mod_proxy_html_2 But since hudson seems to be well behaved it even better to just not use SetOutputFilter and ProxyHTMLURLMap.

If there are problems with hudson sometimes servicing random garbage pages, then the following may help:

SetEnv proxy-nokeepalive 1

mod_proxy with HTTPS

If you'd like to run Hudson with reverse proxy in HTTPS, one user reported that HTTPS needs to be terminated at Hudson, not at the front-end Apache. See this e-mail thread for more discussion.

Alternatively, you can add an additional ProxyPassReverse directive to redirect non-SSL URLs generated by Hudson to the SSL side. Assuming that your webserver is your.host.com, placing the following within the SSL virtual host definition will do the trick:

ProxyRequests     Off
ProxyPreserveHost On

<Proxy http://localhost:8081/hudson*>
  Order deny,allow
  Allow from all
</Proxy>

ProxyPass         /hudson  http://localhost:8081/hudson
ProxyPassReverse  /hudson  http://localhost:8081/hudson
ProxyPassReverse  /hudson  http://your.host.com/hudson

Yet another option is to rewrite the Location headers that contain non-ssl URL's generated by Hudson. If you want to access Hudson from https://www.example.com/hudson, placing the following within the SSL virtual host definition also works:

ProxyRequests     Off
ProxyPreserveHost On
ProxyPass /hudson/ http://localhost:8081/hudson/
<Location /hudson/>
  ProxyPassReverse /
  Order deny,allow
  Allow from all
</Location>
Header edit Location ^http://www.example.com/hudson/ https://www.example.com/hudson/

mod_ajp/mod_proxy_ajp

More info welcome

I wanted to have Hudson running in a different workspace than my normal Tomcat server, but both available via the Apache web server. So, first up, modify Hudson to use a different web and ajp port than Tomcat:

HTTP_PORT=9080
AJP_PORT=9009
...
nohup java -jar "$WAR" --httpPort=$HTTP_PORT --ajp13Port=$AJP_PORT --prefix=/hudson >> "$LOG" 2>&1 &

Then setup Apache so that it knows that the prefix /hudson is being served by AJP in the httpd.conf file:

LoadModule jk_module          libexec/httpd/mod_jk.so

AddModule     mod_jk.c

#== AJP hooks ==
JkWorkersFile /etc/httpd/workers.properties
JkLogFile     /private/var/log/httpd/mod_jk.log
JkLogLevel    info
JkLogStampFormat "[%a %b %d %H:%M:%S %Y] "
JkOptions     +ForwardKeySize +ForwardURICompat -ForwardDirectories
JkRequestLogFormat     "%w %V %T"
# Here are 3 sample applications - 2 that are being served by Tomcat, and Hudson
JkMount  /friki/* worker1
JkMount  /pebble/* worker1
JkMount  /hudson/* worker2

Then finally the workers.conf file specified above, that just tells AJP which port to use for which web application:

# Define 2 real workers using ajp13
worker.list=worker1,worker2
# Set properties for worker1 (ajp13)
worker.worker1.type=ajp13
worker.worker1.host=localhost
worker.worker1.port=8009
worker.worker1.lbfactor=50
worker.worker1.cachesize=10
worker.worker1.cache_timeout=600
worker.worker1.socket_keepalive=1
# Set properties for worker2 (ajp13)
worker.worker2.type=ajp13
worker.worker2.host=localhost
worker.worker2.port=9009
worker.worker2.lbfactor=50
worker.worker2.cachesize=10
worker.worker2.cache_timeout=600
worker.worker2.socket_keepalive=1
worker.worker2.recycle_timeout=300

mod_rewrite

Some people attempted to use mod_rewrite to do this, but this will never work if you do not add a _ProxyPassReverse_. See this thread if you'd like to know why.

The following Apache modules must be installed :

a2enmod rewrite
a2enmod proxy
a2enmod proxy_http
{noformat}A typical set up for mod_rewrite would look like this:
{noformat}# Use last flag because no more rewrite can be applied after proxy pass
RewriteRule       ^/hudson(.*)$  http://localhost:8081/hudson$1 [P,L]
ProxyPassReverse  /hudson        http://localhost:8081/hudson
ProxyRequests     Off

# Local reverse proxy authorization override
# Most unix distribution deny proxy by default (ie /etc/apache2/mods-enabled/proxy.conf in Ubuntu)
<Proxy http://localhost:8081/hudson*>
  Order deny,allow
  Allow from all
</Proxy>

This assumes that you run Hudson on port 8081. For this set up to work, the context path of Hudson must be the same between your Apache and Hudson (that is, you can't run Hudson on http://localhost:8081/ci and have it exposed at http://localhost:80/hudson])

The ProxyRequests Off prevents Apache from functioning as a forward proxy server (except for ProxyPass), it is advised to include it unless the server should function as a proxy.