Azure Application Gateway - Routing Traffic to Web Servers

A simple demonstration to deploy Azure Application Gateway to route traffice to web servers

🎯 Solution

🧰 Prerequisites

This demo, along with its instructions, scripts, and Bicep template, has been specifically designed to be executed in the northeurope region. However, with minimal modifications, you can also try running it in other regions of your choice (the specific steps for doing so are not covered in this context)
- 🛠 Azure CLI Installed & Configured - Get help here
- 🛠 Azure Function Core Tools - Get help here
- 🛠 Bicep Installed & Configured - Get help here
  - 🛠 [Optional] VS Code & Bicep Extenstions - Get help here
- jq - Get help here
- bash or git bash - Get help here

⚙️ Setting up the environment

Get the application code

git clone https://github.com/miztiik/azure-application-gateway-for-web-servers.git
cd azure-application-gateway-for-web-servers

🚀 Prepare the local environment

Ensure you have jq, Azure Cli and bicep working
```
jq --version
func --version
bicep --version
bash --version
az account show
```
🚀 Deploying the Solution
- Stack: Main Bicep The params required for the modules are in params.json. Modify them as needed. The helper deployment script deploy.sh will deploy the main.bicep file. This will create the following resoureces
  - Resource Group(RG)
  - VNet, Subnet & Virtual Machine
    - One Subnet dedicated for the Flexible MySQL Server
  - Virtual Machine(Ubuntu) - 1 - Defined in params.json named vmCount
    - Bootstrapped with custom libs using userData script - Installs Nginx
    - Install Azure Monitoring Agent
  - User Managed Identity - Identity attached to the VM with the following permissions,
    - Monitoring Metrics Publisher
  - Azure Application Gateway
    - Frontend IP Config
    - Backend Pool
    - HTTP Settings
    - Listener
    - Rule
    - Health Probe
    - Diagnostic Settings
  I couldn't figure out a way to add the VMs to the backend pool all in the same template. Will have to figure out a way to do it. For now, I have added the VMs to the backend pool manually after the deployment.
  
  Note - I hacked the template from another repo of mine, so you will see some unused resources(log analytics workspace/queues etc.,). You can safely ignore them, But do remember to clean up your Resource Group to avoid unnecessary costs.
```
# make deploy
sh deployment_scripts/deploy.sh
```
After successfully deploying the stack, Check the Resource Groups/Deployments section for the resources.

🔬 Testing the solution

You can find the Application Gateway Public IP name from the resource blade.

APP_GW_PUBLIC_IP="m-web-srv-app-gw-004-pip"
for i in {1..100};
 do 
 curl ${APP_GW_PUBLIC_IP}
 sleep 2
done

You should see the output like this, You can see the traffic being routed to both the VMs (check the ip address and the hostname)

Hello World from miztiik-automation-vm <b>m-web-srv-app-gw-004-1</b> <b>10.0.1.4</b> on Mon May 29 14:39:46 UTC 2023 
Hello World from miztiik-automation-vm <b>m-web-srv-app-gw-004-1</b> <b>10.0.1.4</b> on Mon May 29 14:39:46 UTC 2023 
Hello World from miztiik-automation-vm <b>m-web-srv-app-gw-004-0</b> <b>10.0.1.5</b> on Mon May 29 14:48:36 UTC 2023 
Hello World from miztiik-automation-vm <b>m-web-srv-app-gw-004-0</b> <b>10.0.1.5</b> on Mon May 29 14:48:36 UTC 2023 
Hello World from miztiik-automation-vm <b>m-web-srv-app-gw-004-1</b> <b>10.0.1.4</b> on Mon May 29 14:39:46 UTC 2023 
Hello World from miztiik-automation-vm <b>m-web-srv-app-gw-004-0</b> <b>10.0.1.5</b> on Mon May 29 14:48:36 UTC 2023 
Hello World from miztiik-automation-vm <b>m-web-srv-app-gw-004-1</b> <b>10.0.1.4</b> on Mon May 29 14:39:46 UTC 2023 
Hello World from miztiik-automation-vm <b>m-web-srv-app-gw-004-1</b> <b>10.0.1.4</b> on Mon May 29 14:39:46 UTC 2023 
Hello World from miztiik-automation-vm <b>m-web-srv-app-gw-004-0</b> <b>10.0.1.5</b> on Mon May 29 14:48:36 UTC 2023 
Hello World from miztiik-automation-vm <b>m-web-srv-app-gw-004-0</b> <b>10.0.1.5</b> on Mon May 29 14:48:36 UTC 2023 
Hello World from miztiik-automation-vm <b>m-web-srv-app-gw-004-1</b> <b>10.0.1.4</b> on Mon May 29 14:39:46 UTC 2023

Troubleshooting : Occasionally the bootstrap script will fail to install the Nginx, resuling in health probe failure. You can check the health probe status from the Application Gateway/Backend Health section. If you see the health probe failing, you can SSH into the VM and install Nginx manually. You can also check the logs from the VM in the Application Gateway/Backend Health section.

You can nudge the vm by using the run command,

📒 Conclusion

In this demonstration, we have shown how to build vms and load balance the traffic using application gateway..
🧹 CleanUp

If you want to destroy all the resources created by the stack, Execute the below command to delete the stack, or you can delete the stack from console as well
- Resources created during Deploying The Solution
- Any other custom resources, you have created for this demo
```
# Delete from resource group
az group delete --name Miztiik_Enterprises_xxx --yes
# Follow any on-screen prompt
```
This is not an exhaustive list, please carry out other necessary steps as maybe applicable to your needs.

📌 Who is using this

This repository aims to show how to Bicep to new developers, Solution Architects & Ops Engineers in Azure.

💡 Help/Suggestions or 🐛 Bugs

Thank you for your interest in contributing to our project. Whether it is a bug report, new feature, correction, or additional documentation or solutions, we greatly value feedback and contributions from our community. Start here