Load Balancing with Apache
Download as KEY, PDF55 likes26,334 views
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.
![# 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)
Load Balancing with Apache
- 1. Load Balancing with Apache Bradley Holt (http://bradley-holt.com/) @BradleyHolt (http://twitter.com/BradleyHolt)
- 2. About Me
- 4. Contributor
- 5. Author http://oreilly.com/catalog/9781449303129/ http://oreilly.com/catalog/9781449303433/
- 7. About Apache Open source Serves over 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
- 8. Alternatives
- 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’s Elastic Load Balancing Rackspace Cloud Load Balancers
- 11. Shared Nothing Architecture (SN)
- 12. Properties of a SN System Each node operates independently No single point of contention PHP is shared nothing by default…
- 13. Breaking SN Sessions require sharing (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 Store sessions 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).
- 16. Required Modules mod_proxy mod_proxy_http (assuming you’re load balancing HTTP requests) mod_proxy_balancer mod_headers (for sticky sessions) mod_rewrite (for advanced con gurations)
- 18. # Create a load 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 traffic to 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 in PHP (your mileage may vary)
- 21. # Create a load 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 Own Sticky Sessions
- 23. # Set a cookie 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 private network 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 on HTTP Method
- 26. # 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
- 27. Consider con guring multiple 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 Testing with Tsung
- 29. Tsung Distributes load testing across 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 guration File
- 31. <?xml version="1.0"?> <!DOCTYPE tsung SYSTEM "/usr/share/tsung/tsung-1.0.dtd"> <tsung loglevel="notice" version="1.0"> <!-- … --> </tsung>
- 33. <!-- Client side setup --> <clients> <client host="test-a" weight="1" maxusers="10000" cpu="4" /> <client host="test-b" weight="1" maxusers="10000" cpu="4" /> </clients>
- 35. <!-- Server side setup --> <servers> <server host="www" port="80" type="tcp" /> </servers>
- 36. Load Setup
- 37. <!-- Load setup --> <load> <arrivalphase phase="1" duration="5" unit="minute" > <users arrivalrate="200" unit="second" /> </arrivalphase> </load>
- 38. Session Setup
- 39. <!-- Session setup --> <session name="default" probability="100" type="ts_http" > <thinktime value="1" random="true" /> <request> <http method="GET" url="/" /> </request> </session>
- 40. Monitoring Setup
- 41. Tsung allows for monitoring 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>
- 43. Reports
- 44. From Scaling CouchDB by Bradley Holt (O’Reilly). Copyright 2011 Bradley Holt, 978-1-449-30343-3
- 45. Graphs
- 46. From Scaling CouchDB by Bradley Holt (O’Reilly). Copyright 2011 Bradley Holt, 978-1-449-30343-3
- 47. Questions?
- 48. Thank You Bradley Holt (http://bradley-holt.com/) @BradleyHolt (http://twitter.com/BradleyHolt) Copyright © 2011 Bradley Holt. All rights reserved.
Editor's Notes
- #2: \n
- #3: \n
- #4: \n
- #5: \n
- #6: \n
- #7: \n
- #8: \n
- #9: \n
- #10: \n
- #11: \n
- #12: \n
- #13: \n
- #14: \n
- #15: \n
- #16: \n
- #17: \n
- #18: \n
- #19: \n
- #20: \n
- #21: \n
- #22: \n
- #23: \n
- #24: \n
- #25: \n
- #26: \n
- #27: \n
- #28: \n
- #29: \n
- #30: \n
- #31: \n
- #32: \n
- #33: \n
- #34: \n
- #35: \n
- #36: \n
- #37: \n
- #38: \n
- #39: \n
- #40: \n
- #41: \n
- #42: \n
- #43: \n
- #44: \n
- #45: \n
- #46: \n
- #47: \n
- #48: \n
- #49: \n