Step by step guide on implementing Azure Application Gateway using Azure Portal

Implementing Azure Application Gateway via the Azure Portal involves several steps.

Below is a step-by-step guide to configure it properly.

Step 1: Prerequisites

Before you start configuring the Azure Application Gateway, make sure the following prerequisites are met:

• An Azure account (Create one if you don't have one already).

• A virtual network (VNet) in which the Application Gateway will be deployed.

• Subnets: Application Gateway requires at least one subnet for its deployment.

• Backend pool: You need the backend servers that you will route traffic to. These could be Azure VM instances, web apps, or external services.

Step 2: Create an Application Gateway

1. Sign in to the Azure Portal:

2. Create a new Application Gateway:

   • In the Azure Portal, search for "Application Gateway" in the top search bar.

   • Select Application Gateway from the search results.

   • Click on + Add to create a new Application Gateway.

3. Configure Basic Settings:

   • Subscription: Choose the subscription you want to use.

   • Resource Group: Select an existing resource group or create a new one.

   • Region: Choose the region where the gateway will be deployed.

   • Name: Provide a unique name for your Application Gateway.

   • Tier: Choose either "Standard" or "WAF" (Web Application Firewall) based on your requirement. The WAF tier provides additional protection for your applications.

   • SKU: Select the appropriate SKU for your Application Gateway (e.g., Standard_v2 or WAF_v2).

   • Virtual Network: Select the virtual network where the Application Gateway will reside.

   • Subnet: Choose an existing subnet or create a new subnet specifically for the Application Gateway.

     • Note: This subnet cannot have other resources (e.g., VMs) deployed in it.

4. Frontend IP Configuration:

   • Frontend IP: You have two options here:

     • Public IP: If you want the Application Gateway to be accessible from the internet, select Public and create a new public IP.

     • Private IP: If the Application Gateway should be accessible only within your virtual network, select Private and assign an internal IP address.

Step 3: Configure Backend Pool

Define Backend Pool

• Under Backend Pool, click Add to define the backend pool, which is a collection of resources (VMs, web apps, etc.) that the Application Gateway will route traffic to.

• You can add individual IP addresses, Azure VMs, or App Services to the pool.

• Click Add after defining the backend pool.

Step 4: Configure HTTP Settings

1. Define HTTP Settings

• Under HTTP Settings, you need to define the configuration for how the Application Gateway will handle incoming requests.

• Add a new HTTP Setting: Configure settings like:

  • Port: Choose the port (usually 80 for HTTP or 443 for HTTPS).

  • Protocol: Select the protocol (HTTP/HTTPS).

  • Cookie-Based Affinity: Optionally enable this if you need session persistence.

  • Authentication: Configure authentication if required.

Enable HTTPS (Optional

If you are using HTTPS, you'll need to upload a valid SSL certificate.

Step 5: Configure Routing Rules

1. Create Listener

• Under Listener, configure a listener for incoming requests.

• Choose the Frontend IP that you created earlier.

• Select the protocol (HTTP or HTTPS).

• If using HTTPS, ensure you upload the appropriate SSL certificate.

2. Configure Rules

Add a Rule to define how the traffic should be routed based on the listener.

• You can configure URL path-based routing, host-based routing, or both.

• For example, route traffic from /images to one backend pool and traffic from /videos to another.

• Assign the appropriate Backend Pool and HTTP Settings for each rule.

3. Configure Redirect (Optional)

If you want to redirect traffic (e.g., HTTP to HTTPS), set up the necessary redirect rules.

Step 6: Configure Health Probes

Create Health Probes:

• Health probes are used to check the health of the backend servers.

• Go to Health Probes and configure the probe settings.

  • You can define the protocol, port, and path to check.

• For example, use HTTP on port 80 to check /healthcheck on the backend.

Step 7: Review and Create the Application Gateway

1. Review Configuration

• Review all your configurations, including the frontend IP, backend pools, HTTP settings, routing rules, and health probes.

• Ensure all resources are correctly configured.

2. Create the Gateway

• After reviewing, click Create to deploy the Application Gateway.

• The deployment process might take a few minutes to complete.

Step 8: Verify the Deployment

1. Monitor the Application Gateway

• Once the Application Gateway is deployed, you can monitor its performance and health from the Monitoring section.

• You can also access the Diagnostics to check for any issues.

2. Test Access

If you used a public IP, try accessing the Application Gateway’s frontend IP (or DNS name if configured) in a browser to ensure it routes the traffic correctly to the backend services.

Step 9: Optional – Configure Autoscaling

If you're using the Standard_v2 or WAF_v2 SKU, you can enable Autoscaling:

• Go to the Autoscaling section of the Application Gateway settings.

• Set the minimum and maximum instances depending on your traffic needs.

Summary

Once the Azure Application Gateway is configured, it will start routing traffic according to the rules you defined, providing load balancing and application security.

You can later adjust settings like scaling, health probes, or routing rules as needed.

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