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![# Enable mod_rewrite
RewriteEngine On
# Send POST, PUT, and DELETEs to "write" balancer
RewriteCond %{REQUEST_METHOD} ^(POST|PUT|DELETE)$
RewriteRule ^/(.*)$ balancer://write$1 [P]
# Send GET, HEAD, and OPTIONS to "read" balancer
RewriteCond %{REQUEST_METHOD} ^(GET|HEAD|OPTIONS)$
RewriteRule ^/(.*)$ balancer://read$1 [P]
# Modify HTTP response headers (e.g. Location)
ProxyPassReverse / balancer://write
ProxyPassReverse / balancer://read](https://image.slidesharecdn.com/load-balancing-with-apache-110325100552-phpapp01/85/Load-Balancing-with-Apache-26-320.jpg)
Uploaded byBradley Holt
Load Balancing with Apache
The document discusses load balancing with the Apache HTTP server, highlighting its ability to support over 100 million websites and its operation modes through various multiprocessing modules. It covers practical techniques for load balancing, including the use of sticky sessions and configurations for Apache modules, along with examples of managing requests. Additionally, it introduces Tsung for distributed load testing, monitoring setup, and session management.
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Load Balancing with Apache
- 1. Load Balancing with Apache Bradley Holt (http://bradley-holt.com/) @BradleyHolt (http://twitter.com/BradleyHolt)
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- 5. Author http://oreilly.com/catalog/9781449303129/ http://oreilly.com/catalog/9781449303433/
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- 7. About Apache Open source Servesover 100 million websites Can run in many different modes, depending on your needs, via MultiProcessing Modules (MPMs) The Apache Software Foundation (ASF) supports many other open source software projects
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- 9. Software Load Balancers HAProxy Varnish Pound Perlbal Squid nginx Linux-HA(High-Availability Linux) on Linux Standard Base (LSB)
- 10. Hosted Load Balancers Amazon’sElastic Load Balancing Rackspace Cloud Load Balancers
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- 12. Properties of aSN System Each node operates independently No single point of contention PHP is shared nothing by default…
- 13. Breaking SN Sessions requiresharing (or require the use of sticky sessions) Databases are the most common single point of contention (this is why eventual consistency is important) Storing variables in memory between requests breaks SN (possible in Java and .NET)
- 14. Practical SN Techniques Storesessions in a memcached cluster—this makes web nodes SN For database applications: • send writes to a write-only master • replicate to multiple read-only nodes • read-only nodes are now effectively SN Clustering/partitioning/sharding can help, too (but painful). Alternatively, use a “NoSQL” database (e.g. CouchDB is SN).
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- 16. Required Modules mod_proxy mod_proxy_http (assumingyou’re load balancing HTTP requests) mod_proxy_balancer mod_headers (for sticky sessions) mod_rewrite (for advanced con gurations)
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- 18. # Create aload balancer named "web-nodes" <Proxy balancer://web-nodes> # Add three load balancer members BalancerMember http://www1.example.com BalancerMember http://www2.example.com BalancerMember http://www3.example.com </Proxy> # Send all requests to the "web-nodes" balancer ProxyPass / balancer://web-nodes
- 19. Apache allows trafficto be balanced by number of requests (lbmethod=byrequests), bytes transferred (lbmethod=bytraffic), or by the number of currently pending requests (lbmethod=bybusyness).
- 20. Sticky Sessions inPHP (your mileage may vary)
- 21. # Create aload balancer named "web-nodes" <Proxy balancer://web-nodes> # Add three load balancer members BalancerMember http://www1.example.com BalancerMember http://www2.example.com BalancerMember http://www3.example.com # Use the PHPSESSID for sticky sessions ProxySet stickysession=PHPSESSID </Proxy> # Send all requests to the "web-nodes" balancer ProxyPass / balancer://web-nodes
- 22. Create Your OwnSticky Sessions
- 23. # Set acookie Header add Set-Cookie "NODE=%{BALANCER_WORKER_ROUTE}e; path=/" env=BALANCER_ROUTE_CHANGED # Create a load balancer named "web-nodes" <Proxy balancer://web-nodes> # Add three load balancer members BalancerMember http://www1.example.com route=1 BalancerMember http://www2.example.com route=2 BalancerMember http://www3.example.com route=3 # Use the NODE cookie for sticky sessions ProxySet stickysession=NODE </Proxy> # Send all requests to the "web-nodes" balancer ProxyPass / balancer://web-nodes
- 24. Use a privatenetwork to connect your load balancer to your balancer members. This allows for dedicated bandwidth and opens up the possibility of offloading SSL handling to the load balancer.
- 25. Route Based onHTTP Method
- 26. # Enable mod_rewrite RewriteEngineOn # Send POST, PUT, and DELETEs to "write" balancer RewriteCond %{REQUEST_METHOD} ^(POST|PUT|DELETE)$ RewriteRule ^/(.*)$ balancer://write$1 [P] # Send GET, HEAD, and OPTIONS to "read" balancer RewriteCond %{REQUEST_METHOD} ^(GET|HEAD|OPTIONS)$ RewriteRule ^/(.*)$ balancer://read$1 [P] # Modify HTTP response headers (e.g. Location) ProxyPassReverse / balancer://write ProxyPassReverse / balancer://read
- 27. Consider con guringmultiple load balancers, removing the load balancer as a single point of failure. This typically involves having two or more load balancers sharing the same IP address, with one con gured as a failover.
- 28. Distributed Load Testingwith Tsung
- 29. Tsung Distributes load testingacross multiple testing clients Can generate huge numbers of concurrent users Monitors CPU, memory, load, and network traffic Simulates dynamic sessions, as described in a con guration le Randomizes traffic patterns based on de ned probabilities Recording and playback of sessions HTML reports and graphs
- 30. XML Con gurationFile
- 31. <?xml version="1.0"?> <!DOCTYPE tsungSYSTEM "/usr/share/tsung/tsung-1.0.dtd"> <tsung loglevel="notice" version="1.0"> <!-- … --> </tsung>
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- 33. <!-- Client sidesetup --> <clients> <client host="test-a" weight="1" maxusers="10000" cpu="4" /> <client host="test-b" weight="1" maxusers="10000" cpu="4" /> </clients>
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- 35. <!-- Server sidesetup --> <servers> <server host="www" port="80" type="tcp" /> </servers>
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- 37. <!-- Load setup--> <load> <arrivalphase phase="1" duration="5" unit="minute" > <users arrivalrate="200" unit="second" /> </arrivalphase> </load>
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- 39. <!-- Session setup--> <session name="default" probability="100" type="ts_http" > <thinktime value="1" random="true" /> <request> <http method="GET" url="/" /> </request> </session>
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- 41. Tsung allows formonitoring using Erlang, SNMP, or Munin
- 42. <!-- Monitoring setup--> <monitoring> <monitor host="www" type="munin" /> <monitor host="www1" type="munin" /> <monitor host="www2" type="munin" /> <monitor host="www3" type="munin" /> </monitoring>
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- 44. From Scaling CouchDBby Bradley Holt (O’Reilly). Copyright 2011 Bradley Holt, 978-1-449-30343-3
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- 46. From Scaling CouchDBby Bradley Holt (O’Reilly). Copyright 2011 Bradley Holt, 978-1-449-30343-3
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- 48. Thank You Bradley Holt (http://bradley-holt.com/) @BradleyHolt (http://twitter.com/BradleyHolt) Copyright © 2011 Bradley Holt. All rights reserved.