Information Technology Reference
In-Depth Information
2
Learning and Recommendations
Following is the learning outcome from this exercise:
2.1
Load Balancers
ELB does not have a private IP and cannot be wrapped around AWS security group.
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Description
ELB does not have a private IP and security group cannot be wrapped around it,
which exposes it and makes it open-for-all to access. This behavior does not
make a sound proposition for inter-server communication between web server
and app server.
•
Recommendation
A software load balancer, like HAProxy [Ref 3], becomes a candidate for load
balancing the application server layer. These HAProxy instances being normal
EC2 instances, has private IP addresses and could be protected by security group
thus making them protected from unauthorized access.
2.2
Auto Discovery of EC2 Nodes
Task is to auto discover the newly instantiated application servers on AWS cloud.
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Description
Application servers being part of auto-scaling group are configured to scale out
and scale in dynamically. There are no provisions in HAProxy to find out new
servers and configure itself accordingly to handle new servers.
•
Recommendation
To use HAProxy in tandem with auto-scaled application server a custom
component was developed which discovers the newly instantiated app server
instance and updates the HAProxy configuration file with app server instance
information. These auto-scaled application servers, once dynamically registered
with HAProxy, can be load balanced by the HAProxy instance.
3
Performance Testing Environment
Performance Testing is an important activity of software life cycle. It ensures that the
delivered software meets customer's expectations - varying load, availability and
scalability. In a virtualized environment such as cloud, testing the deployed
application for its performance becomes an important aspect. This section talks about
the observations made during load testing using Apache JMeter performance testing
tool on AWS. It lists out the parameter and corresponding values on which the
comparison of various web application topologies under auto-scaled environment is
done.
