More AWS: Elastic Load Balancing & Setting up the AWS Command Line

Hello!

As you may have noticed from my previous posts, I have spent the better part of this week playing around with everything Amazon Web Services (AWS) has to offer. In today’s blog, I will be sharing a few more demos that I felt are interesting and may be useful to share with others. Let’s get started!

Creating an Internet-facing Elastic Load Balancer (ELB)

We created an EC2 instance to host an Apache-based web server in the last blog. Head over there again, and make a new EC2 instance and set up an Apache server.

Why do we need 2 instances, you ask?

Having a load balancer that distributes load across a single instance is sort of pointless, ofcourse.
From the AWS Services page navigate to EC2 under the Compute category.
On the EC2 Dashboard page, click Load balancers.
On the Load Balancers page, click Create Load Balancer.
You will now have three Elastic Load Balancer types to choose from:

i. Application Load Balancer: are also known as layer 7 load balancers. These handle HTTP and HTTPS traffic and offer rich HTTP feature support (such as utilizing the HTTP X-Forwarded-For header) as compared to Network and Classic load balancers. Application load balancers have higher latency than Network load balancers but are much more intelligent.

ii. Network Load Balancer: are also known as layer 4 load balancers. These support applications that utilize TLS, TCP and UDP transport protocols. Network load balancers are genrerally used in latency-critical applications.

iii. Classic Load Balancer: are a mix of both Application and Network load balancers because they offer support for both layer 7 load balancing for HTTP/HTTPS and layer 4 load balancing for TCP-based applications.

I will be using Classic Load Balancer for the purpose of this demonstration. Click Create in the Classic Load Balancer tile.
On the Define Load Balancer page, do the following:

i. Enter a Load Balancer name.

ii. Under Create LB Inside, Select the Virtual Private Cloud containing your EC2 instances.

iii. Uncheck Create an internal load balancer since we want to create an internet-facing load balancer.

iv. Under Listener Configuration, add two Load Balancer Protocols: HTTP and HTTPS.

v. Finally, press Next: Assign Security Groups.
On the Assign Security Groups page, select the Security Group you created while creating your EC2 instances and then click Next: Configure Security Settings.

If you do not know what this, please see Step 8 of Creating an EC2 Instance demo in my last blog post here.
SSH into your all of your EC2 instances and do the following:

i. If you do not know how to SSH, please see the Connecting to an EC2 instance via SSH section of my previous blog post here.

ii. Navigate to /var/www/html.
```
 cd /var/www/html
```
iii. Create a file named lb-ping.html.
```
 sudo touch lb-ping.html
```
This html file will be periodically retrieved by the load balancer to ensure your server instance is healthy and running!
On the Configure Health Checks page, do the following:

i. Set Ping Protocol to HTTP.

ii. Set Ping Port to 80.

iii. Set Ping Path to lb-ping.html. We made this file in the previous step.

iv. Click Next: Add EC2 Instances.
Now, on the Add EC2 Instances page, do the following:

i. Add the two EC2 instances you created earlier.

ii. Enable Connection draining. This provides fault tolerance when an EC2 instance goes down for updates or maintenance. The load balancer will prevent a clients connection from breaking by automatically serving remaining HTTP resources from another EC2 instance.

iii. Enable Cross-Zone Load Balancing if you created instances that are in different Availablility Zones. By default, a Classic Load Balancer will only distributed requests in its own Availability Zone only, to make use of EC2 instances in the same region but in different Availability Zones, Cross-Zone Load Balancing should be enabled.

iv. Finally press Next: Add Tags.
On the Add Tags page, press Create Tag to create a new key-value tag. These are useful for management purposes. Click Review and Create when done.
Finally on the Review page, please review the load balancer’s configuration carefully. Once everything is verified, click Create to create the load balancer instance.

Setting up Amazon Command Line

From the AWS Services page navigate to IAM under the Security, Identity, & Compliance category.
On the IAM Dashboard, select Users.
Click Add user.
On the Add user page, do the following:

i. Choose a User name.

ii. Under Access type check Programmatic access since we want to use the AWS CLI. However, uncheck AWS Management Console access as this is not required.

iii. Finally click Next: Permissions.
On the Set permissions page, add the newly-created user to a security group, if any. Otherwise, you can attach security policies to the account directly. I will be enabling the AdministratorAccess policy for this account.
On the Add Tags page, press Create Tag to create a new key-value tag. These are useful for management purposes. Click Next: Review when done.
Finally on the Review page, please review the new user’s configuration carefully. Once everything is verified, click Create user.
Download the CSV file containing your Access Key ID and Secret key and store it a secure place.
Head-over to the Amazon Command Line Interface homepage and download a binary suitable for your OS and architecture.

I will be downloading the Windows 64-bit binary.
Installing the AWS CLI binary should straight-forward, a couple of Nexts on Windows and you should be good to go.
To test whether the installation was successful, open a Command Prompt window and try the following:
```
aws
```
```
aws --version
```
You should see the following output:
Next enter the following in the Command Prompt window:
```
aws configure
```
You will be prompted to enter the following:

i. AWS Secret Key ID - you saved this in Step 8.

ii. AWS Secret Access Key - Step 8 too!

iii. Default region name - From this list, choose the region closest to you.

iv. Default output format - you may either: json, yaml, text or table.
You should now have AWS CLI set up. To learn what you can with the AWS CLI, please see the official documentation!