CS524-Lab 2 Solved

1) Create the Amazon EC2 instances  
You need to create five EC2 instances of the same type you have created in the previous Lab. One of these instances will act as a load balancer; the other four will act as web servers named Server1, Server2, Server3, Server4, as demonstrated below:  

                                                             Incoming traffic  

                                                                                               |  

                                                                                 Load Balance                                                                                   |  

                                                   ____________________________________  

                                               |                             |                             |                             |                                

                       Server1               Server2                Server3              Server4                              2) Install Nginx on each instance  

After launching the instances, use amazon-linux-extras (the Amazon Linux native software manager) to install Nginx on every instance and start the Nginx service.  

To verify the Nginx is working, visit the hosted default webpage through instance's public DNS from an internet browser. You will see the Welcome message (if Nginx http server works properly).  

You need to edit the default index.html file on four servers. This file can be found in the directory /usr/share/nginx/html.  

Use a text editor (such as vi) to Add the header with server ID in the index.html file like following:  

<h1>[SERVER_ID]</h1>

Of course, you need to change SERVER_ID to the particular server name (i.e., Server1, Server2, Server3, or Server4).  

3) Configure the load balancer  
To configure the load balancer, you need to edit the load balancer’s configuration file /etc/nginx/nginx.conf.  

Use a text editor (such as vi) to replace the existing text with the following:   events {  worker_connections 768; 

http {  upstream myapp {  #ip_hash;  server [SERVER_PUBLIC_DNS_NAME] weight=1;  server [SERVER_PUBLIC_DNS_NAME] weight=1;  server [SERVER_PUBLIC_DNS_NAME] weight=1;  server [SERVER_PUBLIC_DNS_NAME] weight=1; 

 server {  listen 80; 

 server_name myapp.com; 

 location / {  proxy_pass http://myapp; 
          
Again, you need to find the public DNS name of your servers and replace each occurrence of the SERVER_PUBLIC_DNS_NAME with the respective string.  

The assignment server[<name>] weight=<number> establishes the weight of the server in the upstream cluster to be equal to the specified <number>. The present default is 1.  To experiment with assigning some servers a greater proportion of the traffic, set weights correspondingly.  

Restart the nginx service

You also need to replace the SERVER_PUBLIC_DNS part with the public DNS of your instances.  

Now you can use the curl command in the shell to visit the balancer, which will distribute traffic among the servers.  

                       $ curl [LOAD_BALANCER_DNS_NAME]  
4) Collect the information on visits to your site  
You can use the visit server tool, provided in the Appendix,  or write your own tool,  to track the distribution of the load. The tool visits the cluster 2000 times and returns the visit count on each server.  

The following example illustrates the  use of this tool:  

                       $ visit_server.rb -d LOAD_BALANCER_DNS_NAME  

The output would look like this:  

Starting to visit load balancing server  
-------------------------  
  Summary  
-------------------------  

Server1 visit counts : 500  

Server2 visit counts : 500  

Server3 visit counts : 500  

Server4 visit counts : 500  

Total visit counts : 2000  

The following table shows three different scenarios of weight combination of the four servers. Configure the nginx.conf file according to these scenarios. Then use visit_server for each scenario and record the outputs.  

# Keep STDOUT 

#orig_stdout = $stdout 

# redirect stdout to /dev/null #$stdout = File.new('/dev/null', 'w') server1_visit_count = 0 server2_visit_count = 0 server3_visit_count = 0 server4_visit_count = 0 # starting to visit load balancing server puts "Starting to visit load balancing server" 

2000.times do 

# visit load balancer #o = `curl #{dns_name}` o = `curl -s #{dns_name}` if o =~ /server\s*1/i server1_visit_count += 1 elsif o =~ /server\s*2/i server2_visit_count += 1 elsif o =~ /server\s*3/i server3_visit_count += 1 elsif o =~ /server\s*4/i server4_visit_count += 1

print "." end 

# redirect output to stdout 

#$stdout = orig_stdout # print visit information puts 

puts '-------------------------' 

puts ' Summary' 

puts '-------------------------' puts "Server1 visit counts : " + server1_visit_count.to_s puts "Server2 visit counts : " + server2_visit_count.to_s puts "Server3 visit counts : " + server3_visit_count.to_s puts "Server4 visit counts : " + server4_visit_count.to_s puts "Total visit counts : " + (server1_visit_count + server2_visit_count + server3_visit_count + server4_visit_count).to_s 

Additional steps are outlined below.  

Create EC2 by using command line  

1.     Use the `script` command to record all the commands you use to create the instance  

2.     Explain every step you have used to achieve your goal  

After having deployed the balancer   

1.     Use the `tcpdump` command to collect all the packets that had been exchanged.   

2.     Analyze the packets and report your observations.   

As an additional step, perform the EC2 backup and restore:  

1.     Register an AMI with your Load Balancer instance image and launch a new EC2 instance with that.

2.     Verify that the new instance has all the files created in the load balancer instance. List and explain all the steps in achieving this goal