Apache Deployment Guide¶
Web Front End Considerations¶
Swift can be configured to work both using an integral web front-end and using a full-fledged Web Server such as the Apache2 (HTTPD) web server. The integral web front-end is a wsgi mini “Web Server” which opens up its own socket and serves http requests directly. The incoming requests accepted by the integral web front-end are then forwarded to a wsgi application (the core swift) for further handling, possibly via wsgi middleware sub-components.
client<—->’integral web front-end’<—->middleware<—->’core swift’
To gain full advantage of Apache2, Swift can alternatively be configured to work as a request processor of the Apache2 server. This alternative deployment scenario uses mod_wsgi of Apache2 to forward requests to the swift wsgi application and middleware.
client<—->’Apache2 with mod_wsgi’<—–>middleware<—->’core swift’
The integral web front-end offers simplicity and requires minimal configuration. It is also the web front-end most commonly used with Swift. Additionally, the integral web front-end includes support for receiving chunked transfer encoding from a client, presently not supported by Apache2 in the operation mode described here.
The use of Apache2 offers new ways to extend Swift and integrate it with existing authentication, administration and control systems. A single Apache2 server can serve as the web front end of any number of swift servers residing on a swift node. For example when a storage node offers account, container and object services, a single Apache2 server can serve as the web front end of all three services.
The apache variant described here was tested as part of an IBM research work. It was found that following tuning, the Apache2 offer generally equivalent performance to that offered by the integral web front-end. Alternative to Apache2, other web servers may be used, but were never tested.
Both Apache2 and mod-wsgi needs to be installed on the system. Ubuntu comes with Apache2 installed. Install mod-wsgi using:
sudo apt-get install libapache2-mod-wsgi
First, change the User and Group IDs of Apache2 to be those used by Swift. For example in /etc/apache2/envvars use:
export APACHE_RUN_USER=swift export APACHE_RUN_GROUP=swift
Create a directory for the Apache2 wsgi files:
sudo mkdir /var/www/swift
Create a file for each service under /var/www/swift.
For a proxy service create /var/www/swift/proxy-server.wsgi:
from swift.common.wsgi import init_request_processor application, conf, logger, log_name = \ init_request_processor('/etc/swift/proxy-server.conf','proxy-server')
For an account service create /var/www/swift/account-server.wsgi:
from swift.common.wsgi import init_request_processor application, conf, logger, log_name = \ init_request_processor('/etc/swift/account-server.conf', 'account-server')
For an container service create /var/www/swift/container-server.wsgi:
from swift.common.wsgi import init_request_processor application, conf, logger, log_name = \ init_request_processor('/etc/swift/container-server.conf', 'container-server')
For an object service create /var/www/swift/object-server.wsgi:
from swift.common.wsgi import init_request_processor application, conf, logger, log_name = \ init_request_processor('/etc/swift/object-server.conf', 'object-server')
Create a /etc/apache2/conf.d/swift_wsgi.conf configuration file that will define a port and Virtual Host per each local service. For example an Apache2 serving as a web front end of a proxy service:
#Proxy NameVirtualHost *:8080 Listen 8080 <VirtualHost *:8080> ServerName proxy-server LimitRequestBody 5368709122 WSGIDaemonProcess proxy-server processes=5 threads=1 WSGIProcessGroup proxy-server WSGIScriptAlias / /var/www/swift/proxy-server.wsgi LimitRequestFields 200 ErrorLog /var/log/apache2/proxy-server LogLevel debug CustomLog /var/log/apache2/proxy.log combined </VirtualHost>
Notice that when using Apache the limit on the maximal object size should be imposed by Apache using the LimitRequestBody rather by the swift proxy. Note also that the LimitRequestBody should indicate the same value as indicated by max_file_size located in both /etc/swift/swift.conf and in /etc/swift/test.conf. The Swift default value for max_file_size (when not present) is 5368709122. For example an Apache2 serving as a web front end of a storage node:
#Object Service NameVirtualHost *:6200 Listen 6200 <VirtualHost *:6200> ServerName object-server WSGIDaemonProcess object-server processes=5 threads=1 WSGIProcessGroup object-server WSGIScriptAlias / /var/www/swift/object-server.wsgi LimitRequestFields 200 ErrorLog /var/log/apache2/object-server LogLevel debug CustomLog /var/log/apache2/access.log combined </VirtualHost> #Container Service NameVirtualHost *:6201 Listen 6201 <VirtualHost *:6201> ServerName container-server WSGIDaemonProcess container-server processes=5 threads=1 WSGIProcessGroup container-server WSGIScriptAlias / /var/www/swift/container-server.wsgi LimitRequestFields 200 ErrorLog /var/log/apache2/container-server LogLevel debug CustomLog /var/log/apache2/access.log combined </VirtualHost> #Account Service NameVirtualHost *:6202 Listen 6202 <VirtualHost *:6202> ServerName account-server WSGIDaemonProcess account-server processes=5 threads=1 WSGIProcessGroup account-server WSGIScriptAlias / /var/www/swift/account-server.wsgi LimitRequestFields 200 ErrorLog /var/log/apache2/account-server LogLevel debug CustomLog /var/log/apache2/access.log combined </VirtualHost>
Next stop the Apache2 and start it again (apache2ctl restart is not enough):
apache2ctl stop apache2ctl start
Edit the tests config file and add:
web_front_end = apache2 normalized_urls = True
Also check to see that the file includes max_file_size of the same value as used for the LimitRequestBody in the apache config file above.
We are done. You may run functional tests to test - e.g.:
cd ~swift/swift ./.functests