Working with Elastic

Load Balancing
55 minutes8 Credits

Rate Lab

SPL-03 - Version 4.3.6

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Lab Overview
This lab introduces the concept of Elastic Load Balancing. In this lab you will
use Elastic Load Balancing to load balance traffic across multiple Amazon
Elastic Compute Cloud (EC2) instances in a single Availability Zone. You will
deploy a simple application on multiple Amazon EC2 instances and observe
load balancing by viewing the application in your browser.
 First, you will launch a pair of instances, bootstrap them to install web servers
and content, and then access the instances independently using Amazon EC2
DNS records. Next, you will set up Elastic Load Balancing, add your instances
to the load balancer, and then access the DNS record again to watch your
requests load balance between servers. Finally, you will view Elastic Load
Balancing metrics in Amazon CloudWatch.

The following diagram provides a high-level overview of the architecture you

will implement in this exercise.

Topics covered
This lab will take you through:

 Launching a multiple server web farm on Amazon EC2.

 Using bootstrapping techniques to configure Linux instances with
Apache, PHP, and a simple PHP application downloaded from Amazon
Simple Storage Service (S3).
 Creating and configuring a load balancer that will sit in front of your
Amazon EC2 web server instances.
 Viewing Amazon CloudWatch metrics for the load balancer.
Technical knowledge prerequisites
To successfully complete this lab, you should be familiar with the AWS
Management Console.

Elastic Load Balancing

Elastic Load Balancing automatically distributes incoming application traffic
across multiple Amazon EC2 instances. It enables you to achieve greater
levels of fault tolerance in your applications, seamlessly providing the required
amount of load balancing capacity needed to distribute application traffic.

Achieve higher levels of fault tolerance for your applications by using Elastic
Load Balancing to automatically route traffic across multiple instances and
multiple Availability Zones. Elastic Load Balancing ensures that only healthy
Amazon EC2 instances receive traffic by detecting unhealthy instances and
rerouting traffic across the remaining healthy instances. If all of your Amazon
EC2 instances in one Availability Zone are unhealthy, and you have set up
Amazon EC2 instances in multiple Availability Zones, Elastic Load Balancing
will route traffic to your healthy Amazon EC2 instances in those other zones.

Elastic Load Balancing automatically scales its request-handling capacity to

meet the demands of application traffic. Additionally, Elastic Load Balancing
offers integration with Auto Scaling to ensure that you have back-end capacity
to meet varying levels of traffic levels without requiring manual intervention.

Elastic Load Balancing works with Amazon Virtual Private Cloud (VPC) to
provide robust networking and security features. You can create an internal
(non-Internet facing) load balancer to route traffic using private IP addresses
within your virtual network. You can implement a multi-tiered architecture
using internal and Internet-facing load balancers to route traffic between
application tiers. With this multi-tier architecture, your application infrastructure
can use private IP addresses and security groups, allowing you to expose only
the Internet-facing tier with public IP addresses.

Elastic Load Balancing provides integrated certificate management and SSL

decryption, allowing you to centrally manage the SSL settings of the load
balancer and offload CPU-intensive work from your instances.

This lab guide explains basic concepts of Elastic Load Balancing in a step-by-
step fashion. However, it can only give a brief overview of Elastic Load
Balancing concepts. For further information,
see http://aws.amazon.com/elasticloadbalancing/.
 Start Lab

1. At the top of your screen, launch your lab by clicking  Start Lab
If you are prompted for a token, use the one distributed to you (or credits you
have purchased).

A status bar shows the progress of the lab environment creation process. The
AWS Management Console is accessible during lab resource creation, but
your AWS resources may not be fully available until the process is complete.

2. Open your lab by clicking  Open Console

This will automatically log you into the AWS Management Console.

Please do not change the Region unless instructed.

Common login errors

Error : Federated login credentials

If you see this message:

 Close the browser tab to return to your initial lab window

 Wait a few seconds
 Click  Open Console  again
You should now be able to access the AWS Management Console.

Error: You must first log out

 If you see the message, You must first log out before logging into a
different AWS account:
 Click click here
 Close your browser tab to return to your initial Qwiklabs window
 Click  Open Console  again

Task 1: Launch Web Servers

In this task, you will launch two Amazon Linux EC2 instances, with an Apache
PHP web server and basic application installed on initialization. You will also
demonstrate a simple example of bootstrapping instances using the Amazon
EC2 metadata service.

Amazon Machine Images (AMIs) and instances

Amazon EC2 provides templates known as Amazon Machine Images
(AMIs) that contain a software configuration (for example, an operating
system, an application server, and applications). You use these templates to
launch an instance, which is a copy of the AMI running as a virtual server in
the cloud.
You can launch different types of instances from a single AMI. An instance
typeessentially determines the hardware capabilities of the virtual host
computer for your instance. Each instance type offers different compute and
memory capabilities. Select an instance type based on the amount of memory
and computing power that you need for the application or software that you
plan to run on the instance. You can launch multiple instances from an AMI.
Your instance keeps running until you stop or terminate it, or until it fails. If an
instance fails, you can launch a new one from the AMI.
 When you create an instance, you will be asked to select an instance type.
The instance type you choose determines how much throughput and
processing cycles are available to your instance.

3. On the Services menu, click EC2.
4. Click Launch Instance
5. In the row for the Amazon Linux 2 AMI, click Select
The t2.micro instance type, which is the lowest-cost option, should be
automatically selected.
6. Click  Next: Configure Instance Details  then configure:
 Number of instances: 
 Network: Lab VPC
7. Scroll to the bottom of the screen, then expand  Advanced Details.
8. Enter the following into User data:
#!/bin/sh
yum -y install httpd php
chkconfig httpd on
systemctl start httpd.service
cd /var/www/html
wget https://s3-us-west-2.amazonaws.com/us-west-2-aws-training/awsu-
spl/spl-03/scripts/examplefiles-elb.zip
unzip examplefiles-elb.zip
This will allow you to bootstrap your instance. It will install Apache and PHP
and sample code (PHP scripts) needed for this lab when the instance is
created and launched. User data provides a mechanism to pass data or a
script to the Amazon metadata service, which instances can access at launch
time.

Tip If you type this text instead of copying it, press SHIFT+ENTER to create
new lines in the text box.
9. Click  Next: Add Storage
You will use the default storage device configuration.

10. Click  Next: Add Tags

11. Click  Add Tag  then configure:
 Key: 
 Value: 
This name, more correctly known as a tag, will appear in the console when the
instance launches. It makes it easy to keep track of running machines in a
complex environment. Use a name that you can easily recognize and
remember.

12. Click  Next: Configure Security Group  then configure:

 Security group name: 
 Description: 
 A security group acts as a firewall that controls the traffic allowed into a group
of instances. When you launch an Amazon EC2 instance, you can assign it to
one or more security groups. For each security group, you add rules that
govern the allowed inbound traffic to instances in the group. All other inbound
traffic is discarded. You can modify rules for a security group at any time. The
new rules are automatically enforced for all existing and future instances in the
group.
By default, AWS creates a rule that allows Secure Shell (SSH) access from
any IP address. It is highly recommended that you restrict terminal access to
the ranges of IP addresses (e.g., IPs assigned to machines within your
company) that have a legitimate business need to administer your Amazon
EC2 instance. Because the lab image you are using will be recycled within two
hours, you can bypass this step for the lab.
13. Click  Add Rule  then configure:
 Type: HTTP
 Source: Anywhere
 Click Review and Launch
This will add a default handler for HTTP that will allow requests from
anywhere on the Internet. Since you want this web server to be accessible to
the general public.

14. Review your choices, and then click Launch

 You may see a warning on this screen that “Your security group … is open to
the world.” This is a result of not restricting SSH access to your machine, as
described earlier. For the purposes of this lab only, you may ignore this
warning.
15. In the Select an existing key pair or create a new key
pair window:
 Click  I acknowledge that...
 Click Launch Instances
A status page notifies you that your instances are launching.

16. Click View Instances

17. Wait for your instances to display:

 Instance State:  running
 Status Checks:  2/2 checks passed
This indicates that you instance is now fully available for us.

 This may take a few minutes. You can refresh the status of your instances by
clicking the refresh  icon.
 Task 2: Connect to Each Web Server
In this task, you will:

 Retrieve the public DNS entries for both of your EC2 instances
 Point your browser at each DNS entry to access your instances web
server
All Amazon EC2 instances are assigned two IP addresses at launch: a private
IP address (RFC 1918) and a public IP address that are directly mapped to
each other through Network Address Translation (NAT). Private IP addresses
are only reachable from within the Amazon EC2 network. Public addresses
are reachable from the Internet.
Amazon EC2 also provides an internal DNS name and a public DNS
name that map to the private and public IP addresses, respectively. The
internal DNS name can only be resolved within Amazon EC2. The public DNS
name resolves to the public IP address outside the Amazon EC2 network and
to the private IP address within the Amazon EC2 network.
18. Select  your first Amazon EC2 instance.
19. Copy the Public DNS (IPv4) value to your Clipboard.
It will look something like ec2-54-84-236-205.compute-1.amazonaws.com.
20. Open a new browser window, paste the Public DNS value into the
address bar, and press ENTER. Your browser will display a screen like
this:
 This is the web page returned by the PHP script that was installed when the
instance was started. It is a simple script that interrogates the metadata
service on each machine and returns the instance ID and the name of the
Availability Zone in which the instance is running.

21. Repeat the previous two steps for your second instance.
Notice that each machine displays a different instance ID. This will help you
identify which instance is processing your request when you put a load
balancer in front of them.

If you see an error instead of the instance ID and Availability Zone when you
access the instances from the browser, try again after a couple of minutes. It’s
possible that the bootstrapping script is still running and has not yet completed
installing and starting the web server and PHP application. If errors persist,
verify that you entered the bootstrap script correctly when you launched your
instances and that the security group has port 80 open.

Task 3: Create a Load Balancer

You now have two web servers. Now you need a load balancer in front of
these servers to give your users a single location for accessing both and to
balance user requests across them. In this task, you will be create a simple
HTTP application load balancer.

22. In the AWS Management Console, on the left navigation pane,

click Load Balancers.
23. Click Create Load Balancer
24. Below Application Load Balancer, click Create then configure:
 Name: 
 VPC: Lab VPC
 Select  all of the availability zones
 Click  Next: Configure Security Settings
25. On Step 2, click  Next:Configure Security Groups
26. On Step 3:
 De-select  default
 Select  MyLBInstances
 Click  Next: Configure Routing
27. For Name: enter 
28. Expand  Advanced health check settings then configure:
 Healthy threshold: 
 Click  Next: Register Targets
The ELB will periodically test the ping path on each of your web service
instances to determine health: a 200 HTTP response code indicates a healthy
status, and any other response code indicates an unhealthy status. If an
instance is unhealthy and continues in that state for a successive number of
checks (unhealthy threshold), the load balancer will remove it from service
until it recovers.
In this configuration, making the ping path just a slash (/) will return the default
page—the PHP-generated page seen earlier.
The healthy threshold is the number of successful checks the load balancer
expects to see in a row before bringing an instance into service behind the
load balancer. The lower value will speed things up for this exercise.
29. Select  both of your instances.
30. Click Add to registered
31. Click  Next: Review
32. Review your configuration, then click Create
Your application load balancer will be created.

33. Click Close
It will take a couple of minutes to start up the load balancer, attach your web
servers, and pass the health checks.

34. Wait for the State to display active.

35. Copy the DNS name to your clipboard.
36. Open a new browser tab and then:

 Paste the DNS name

 Press Enter
37. Refresh your browser a few times.
You will notice that the Amazon EC2 Instance IDs change. This means that
the repeated responses are coming back through your two different web
servers.

Load balancers can span Availability Zones, and they also scale elastically as
needed to handle demand. Therefore, you should always access a load
balancer by DNS hostname, and not by IP address. A load balancer may have
multiple IP addresses associated with its DNS hostname.

38. In the AWS Management Console, in the left navigation pane,

click Target Groups
 myTarget should be selected.
39. Click the Targets tab.
Notice that both of your instances are healthy.

Task 4: View Elastic Load Balancing

CloudWatch Metrics
In this task, you will use Amazon CloudWatch to monitor your ELB. Elastic
Load Balancing automatically reports load balancer metrics to CloudWatch.

Amazon CloudWatch provides monitoring for AWS cloud resources and the
applications customers run on AWS. Developers and system administrators
can use it to collect and track metrics, gain insight, and react immediately to
keep their applications and businesses running smoothly. CloudWatch
monitors AWS resources such as Amazon EC2 and Amazon Relational
Database Service (RDS) DB instances and can also monitor custom metrics
generated by your applications and services. With CloudWatch, you gain
system-wide visibility into resource use, application performance, and
operational health.

Amazon CloudWatch provides a reliable, scalable, and flexible monitoring

solution that you can start using within minutes. You no longer need to set up,
manage, or scale your own monitoring systems and infrastructure. Using
CloudWatch, you can easily monitor as much or as little metric data as you
need. CloudWatch lets you programmatically retrieve your monitoring data,
view graphs, and set alarms to help you troubleshoot, spot trends, and take
automated action based on the state of your cloud environment.

40. In the AWS Management Console, on the Services menu,

click CloudWatch.
41. In the left navigation pane, click Metrics.
42. Click ApplicationELB
43. Explore the metrics that are being reported to CloudWatch.
 Load balancing metrics include latency, request count, and healthy and
unhealthy host counts. Metrics are reported as they are encountered and can
take several minutes to show up in CloudWatch.

End Lab
Follow these steps to close the console, end your lab, and evaluate the
experience.

44. Return to the AWS Management Console.

45. On the navigation bar,

click <yourusername>@<AccountNumber>, and then click Sign Out.
46. Click  End Lab
47. Click  OK
48. (Optional):

 Select the applicable number of stars 

 Type a comment
 Click Submit
o 1 star = Very dissatisfied
o 2 stars = Dissatisfied
o 3 stars = Neutral
o 4 stars = Satisfied
o 5 stars = Very satisfied
You may close the dialog if you don't want to provide feedback.

Conclusion
  Congratulations! You now have successfully:
 Launched a multiple server web farm on Amazon EC2
 Used bootstrapping techniques to configure Linux instances with
Apache, PHP, and a simple PHP application
 Created and configured a load balancer that sits in front of your Amazon
EC2 web server instances
 Viewed Amazon CloudWatch metrics for the load balancer

Additional Resources
 Elastic Load Balancing and Elastic Load Balancing pricing
 AWS Training and Certification
For feedback, suggestions, or corrections, please email: aws-course-
feedback@amazon.com