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authorPrashanth Pai <ppai@redhat.com>2013-10-21 15:05:33 +0530
committerLuis Pabon <lpabon@redhat.com>2013-10-23 18:54:17 -0700
commitade571006d145b0ade2094a1840b67927a18d6d5 (patch)
treefe05a1bbf7a4f6d12d4ab076a1414bc3769c0d32 /doc/markdown
parent11e2be75faa5af4f5c724c61447559693cd05b7f (diff)
Deploy Apache as web front-end for gluster-swift
Swift can alternatively be configured to work as a request processor of Apache server. This alternative deployment scenario uses mod_wsgi of Apache to forward requests to the swift wsgi application and middleware. 'client' <---> 'Apache2+mod_wsgi' <---> 'middleware' <---> 'core swift' Change-Id: If396dcbdf651af0dce55b951cd2eaadc6783384f Signed-off-by: Prashanth Pai <ppai@redhat.com> Reviewed-on: http://review.gluster.org/6116 Reviewed-by: Luis Pabon <lpabon@redhat.com> Tested-by: Luis Pabon <lpabon@redhat.com>
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+## Deploying Apache as front end for Openstack Swift in Fedora/RHEL
+
+NOTE: This guide is for manual deployment. A shell script to automate the following
+is present in extras/apache-deploy.
+
+### Architecture
+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 config.
+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.
+
+### Steps
+
+Installing Apache with mod_wsgi module:
+
+ yum install httpd mod_wsgi
+
+Create a directory for Apache wsgi files:
+
+ mkdir /var/www/swift
+
+Create a wsgi file for each service under /var/www/swift
+
+#### /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')
+
+#### /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')
+
+#### /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')
+
+#### /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 */etc/httpd/conf.d/swift_wsgi.conf* configuration file that will define
+port and Virtual Host per each local service.
+
+ WSGISocketPrefix /var/run/wsgi
+
+ #Proxy Service
+ Listen 8080
+ <VirtualHost *:8080>
+ ServerName proxy-server
+ LimitRequestBody 5368709122
+ WSGIDaemonProcess proxy-server processes=5 threads=1 user=swift
+ WSGIProcessGroup proxy-server
+ WSGIScriptAlias / /var/www/swift/proxy-server.wsgi
+ LimitRequestFields 200
+ ErrorLog /var/log/httpd/proxy-server.log
+ LogLevel debug
+ CustomLog /var/log/httpd/proxy.log combined
+ </VirtualHost>
+
+ #Object Service
+ Listen 6010
+ <VirtualHost *:6010>
+ ServerName object-server
+ WSGIDaemonProcess object-server processes=5 threads=1 user=swift
+ WSGIProcessGroup object-server
+ WSGIScriptAlias / /var/www/swift/object-server.wsgi
+ LimitRequestFields 200
+ ErrorLog /var/log/httpd/object-server.log
+ LogLevel debug
+ CustomLog /var/log/httpd/access.log combined
+ </VirtualHost>
+
+ #Container Service
+ Listen 6011
+ <VirtualHost *:6011>
+ ServerName container-server
+ WSGIDaemonProcess container-server processes=5 threads=1 user=swift
+ WSGIProcessGroup container-server
+ WSGIScriptAlias / /var/www/swift/container-server.wsgi
+ LimitRequestFields 200
+ ErrorLog /var/log/httpd/container-server.log
+ LogLevel debug
+ CustomLog /var/log/httpd/access.log combined
+ </VirtualHost>
+
+ #Account Service
+ Listen 6012
+ <VirtualHost *:6012>
+ ServerName account-server
+ WSGIDaemonProcess account-server processes=5 threads=1 user=swift
+ WSGIProcessGroup account-server
+ WSGIScriptAlias / /var/www/swift/account-server.wsgi
+ LimitRequestFields 200
+ ErrorLog /var/log/httpd/account-server.log
+ LogLevel debug
+ CustomLog /var/log/httpd/access.log combined
+ </VirtualHost>
+
+(Re)Start Apache server:
+
+ service httpd stop
+ service httpd start
+
+### Troubleshooting
+
+* Make sure you have set SElinux to Permissive or Disabled by editing
+ */etc/sysconfig/selinux*. You will need to reboot your system for the
+ changed value to take effect. On restart, you can confirm this by running:
+
+ getenforce
+
+* Make sure conf files in /etc/swift are accessible by swift user:
+
+ chown swift:swift /etc/swift/*
+
+* Make sure the directory */var/lib/swift* exists should you see the following
+ error in /var/log/httpd/error_log
+
+ [Fri Oct 20 02:05:25.617290 2013] [:alert] [pid 3491] (2)No such file or
+ directory: mod_wsgi (pid=3491): Unable to change working directory to
+ '/var/lib/swift'
+
+* Make sure the port numbers in */etc/httpd/conf.d/swift_wsgi.conf* and
+ */etc/swift/*conf* files are same.
+
+* For errors in logs like the following:
+
+ 13)Permission denied: mod_wsgi (pid=26962): Unable to connect to WSGI
+ daemon process '<process-name>' on '/etc/httpd/logs/wsgi.26957.0.1.sock'
+ after multiple attempts.
+
+ Refer: https://code.google.com/p/modwsgi/wiki/ConfigurationIssues#Location_Of_UNIX_Sockets
+
+* If your swift deployment uses some authentication mechanism that uses
+ HTTP_AUTHORIZATION variable, you need to turn on WSGIPassAuthorization as
+ described here:
+
+ https://code.google.com/p/modwsgi/wiki/ConfigurationDirectives#WSGIPassAuthorization
+
+#### Issue with gluster-swift
+Unlike vanilla swift that runs as *swift* user, gluster-swift runs all four
+swift servers as *root* user.
+
+But mod_wsgi does not allow invoking wsgi applications as root:
+https://code.google.com/p/modwsgi/wiki/ConfigurationDirectives#WSGIDaemonProcess
+
+A workaround is to mount gluster volume as root beforehand:
+
+ mount -t glusterfs localhost:myvolume /mnt/gluster-object/myvolume
+
+
+### More information
+
+* There is a Ubuntu specific guide to deploy Apache with Openstack Swift here:
+ http://docs.openstack.org/developer/swift/apache_deployment_guide.html
+
+* Example apache configuration from swift source can be found here:
+ https://github.com/openstack/swift/tree/master/examples