elb demos updated

Author: JaimeSalas

04-cloud/aws/09-elb/demos/01-setup/readme.md

@@ -71,7 +71,11 @@ VPC_ID=$(aws ec2 create-vpc --cidr-block 172.31.0.0/16  \
   | jq -r '.Vpc."VpcId"')
 ```
 
-> Enable DNS hostnames from console
+> Enable DNS hostnames from console or using AWS CLI as follows:
+
+```bash
+aws ec2 modify-vpc-attribute --vpc-id $VPC_ID --enable-dns-hostnames "{\"Value\":true}"
+```
 
 ### Create web tier subnets
 
@@ -193,6 +197,8 @@ IMAGE_ID=ami-0302f42a44bf53a45
 
 ### Create web instances
 
+> Ensure that `devops_trainer_key` is created in the desired region
+
 ```bash
 aws ec2 run-instances \
     --image-id $IMAGE_ID \
@@ -202,7 +208,7 @@ aws ec2 run-instances \
     --security-group-ids $WEBSG \
     --associate-public-ip-address \
     --private-ip-address 172.31.1.21 \
-    --tag-specifications ResourceType=instance,Tags='[{Key=name,Value=web1}]'
+    --tag-specifications ResourceType=instance,Tags='[{Key=Name,Value=web1}]'
 ```
 
 ```bash
@@ -214,7 +220,7 @@ aws ec2 run-instances \
     --security-group-ids $WEBSG \
     --associate-public-ip-address \
     --private-ip-address 172.31.2.22 \
-    --tag-specifications ResourceType=instance,Tags='[{Key=name,Value=web2}]'
+    --tag-specifications ResourceType=instance,Tags='[{Key=Name,Value=web2}]'
 ```
 
 ```bash

04-cloud/aws/09-elb/demos/02-user-data/readme.md

@@ -6,8 +6,8 @@ Create `install-docker.txt`
 
 ```bash
 #!/bin/bash
-sudo dnf update
-sudo dnf install docker -y
+sudo yum update -y
+sudo yum install -y docker
 sudo systemctl start docker
 sudo systemctl enable docker
 sudo usermod -aG docker $USER
@@ -59,7 +59,7 @@ With this we're finally ready to try to start our instance with user data:
 > NOTE: We have taken the image id from region AMI Catalog
 
 ```bash
-aws ec2 run-instances --image-id ami-07355fe79b493752d \
+aws ec2 run-instances --image-id ami-0ef0975ebdd78b77b \
  --count 1 --instance-type t3.micro \
  --key-name dublin_key --subnet-id $SUBNET --security-group-ids $SSHSG \
  --region eu-west-1 \

04-cloud/aws/09-elb/demos/03-web-tier-deploy/readme.md

@@ -1,6 +1,6 @@
 # Demo
 
-We're going to SSH into web1 and deploy the web front end using `Docker`. We're then going to browse directly to web1's public IP address and verify that the web front end is actually working. 
+We're going to SSH into web1 and deploy the web front end using `Docker`. We're then going to browse directly to web1's public IP address and verify that the web frontend is actually working. 
 
 - SSH into `web1`
 - Deploy the front end using Docker

04-cloud/aws/09-elb/demos/10-provisioning-db/readme.md

@@ -9,11 +9,12 @@ ssh -i "your_key" ec2-user@<public_dns>
 Install Docker
 
 ```bash
-sudo dnf update
-sudo dnf install docker -y
+# Install Docker
+sudo yum update -y
+sudo yum install -y docker
 sudo systemctl start docker
 sudo systemctl enable docker
-sudo usermod -aG docker $USER 
+sudo usermod -aG docker $USER
 newgrp docker
 ```
 
@@ -30,7 +31,7 @@ docker run -d -p 27017:27017 \
 
 Connect to an app tier instance, for example `app1`
 
-Ping to db instance
+Ping to db instance using the private DNS
 
 ```bash
 nslookup ip-172-31-101-99.eu-west-3.compute.internal
@@ -51,7 +52,7 @@ Check Mongo connectivity. Test Mongo connectivity. From EC2 Dashboard, we can ch
 - 172.31.101.99
 
 ```bash
-sudo dnf -y install telnet
+sudo yum -y install telnet
 telnet ip-172-31-101-99.eu-west-3.compute.internal 27017
 ```
 

04-cloud/aws/09-elb/readme.md

@@ -50,6 +50,26 @@ Right now, we need to SSH into each machine to install Docker. We can avoid this
 
 ## Creating and HTTP Target Group
 
+### What is a Target Group?
+
+A target group in AWS is a key component of Elastic Load Balancing (ELB) that serves as a logical grouping of targets to which traffic can be routed. Here are the main points about target groups:
+
+1. Purpose: Target groups are used to distribute incoming traffic across multiple targets, such as EC2 instances, IP addresses, or Lambda functions.
+
+2. Load Balancer Association: They are associated with Application Load Balancers, Network Load Balancers, or Gateway Load Balancers to define where traffic should be directed.
+
+3. Health Checks: Target groups allow you to configure health checks to ensure that traffic is only routed to healthy targets.
+
+4. Routing Rules: You can create routing rules in your load balancer to direct specific types of requests to different target groups.
+
+5. Auto Scaling Integration: Target groups can be used with Auto Scaling groups to automatically register or deregister instances as they are launched or terminated.
+
+6. Flexibility: You can register the same target with multiple target groups, allowing for flexible traffic distribution strategies.
+
+7. Attributes: Target groups have configurable attributes such as deregistration delay, load balancing algorithm, and stickiness settings.
+
+8. Monitoring: They provide metrics and health status information for your targets, helping you monitor the performance of your application.
+
 ### Supported Protocols
 
 - HTTP
@@ -117,11 +137,11 @@ We're going to deploy the web front end on `web2` and `web3` and add those insta
 
 ### Stickiness Duration
 
-- How long load balancer will maintain sticky session between clinet and target
+- How long load balancer will maintain sticky session between client and target
 - Load balancer sets a browser cookie with a unique, encrypted value
 - Client sends back the cookie with each subsequent request
 - Between 1 second and 7 days
 
 [Demo: Sticky Sessions](./demos/11-sticky-session/readme.md)
 
-[Demo: Idle Timeout]()
+[Demo: Idle Timeout](./demos/12-idle-timeout.md/readme.md)