Simplifying Container App Management with Path-Based Routing in Azure Application Gateway

Overview

Path-based routing is a technique used in networking and web application routing to direct incoming traffic to different destinations based on the path component of the Uniform Resource Locator (URL).
In path-based routing, the URL path is used as a routing criterion to direct the request to the appropriate destination. For example, a web server or a load balancer may use the path component of the URL to route requests to different backends or services.

Path-based routing can direct requests for the web interface to a different backend or service then requests for the API, thus allowing for more granular control over traffic routing.

Introduction Container App

A container app is an application that is packaged and deployed using containerization technology. Containerization is a way to package an application along with its dependencies into a self-contained unit called a container. Containers can be easily moved from one environment to another, making them ideal for deploying applications to the cloud.

Step-by-Step Guide

1. Create a container app

• In the Azure portal, search for the container app
• Click on Create Container app
• Choose your resource group
• Enter Container app name – mycontainerapp1
• Choose a region
• Click on Create New Container Apps Environment
• Under the Basic and Monitoring tab, keep it default.
• Under Networking tab
• Select yes Use your virtual network
• Select your Virtual network and infrastructure subnet and click on Create
• Click on Next: Appsettings
• Choose the image, and ingress should be enabled
• Click on Review + Create
• And click on create

Create One more Container app the same way on the same Virtual network and region

Application Gateway

Azure Application Gateway is a web traffic load balancer and application delivery controller (ADC) that provides high scalability, security, and availability for web applications.

It is a fully managed service in Azure that provides several advanced features, such as SSL offloading, SSL termination, URL-based routing, path-based routing, session affinity, and web application firewall (WAF) capabilities.

Application Gateway enables you to route traffic to multiple backend servers based on various routing rules, such as cookie-based affinity, session persistence, and round-robin load balancing. It can also perform health checks on your backend servers and automatically remove unhealthy servers from the pool.

With Application Gateway, you can manage and optimize traffic to your web applications, improve application performance and availability, and protect your applications from common web application attacks.

2. Create and configure Application Gateway

• Click on Create Application gateway
• Choose your resource group
• Enter Container app name – mycontainerapp1
• Choose a region – Select the region where your Container Apps is provisioned.
• Select Standard V2 for tier
• Enable autoscaling – Leave as default
• Availability zone – Choose None. Availability Zones are advised for higher availability in production environments.
• HTTP2 – keep it default.
• Choose the virtual network that your container app is associated with.
• Click on Manage subnet configuration
  select +Subnet Enter the name of the subnet
• Keep the default values for the remaining parameters.
• To create the new subnet, choose Save.
• Create a subnet for the application gateway.
• Close the Subnets window. To return to the Create application gateway window

• Click on Next: Frontends to proceed.
• On the Frontends tab
• Select Public for Frontend IP address type
• In Public IP address – Select Add new. Enter the name of your frontend and select OK

• Click on Next: backends to proceed.
• The backend pool is used to direct requests to the right backend servers.
• The following resources can be combined to create backend pools:

1. NICs
2. Public IP addresses
3. Internal IP addresses
4. Virtual Machine Scale Sets
5. Fully qualified domain names (FQDN)
6. Multi-tenant back-ends like Azure App Service and Container Apps

• Here we create a backend pool that targets the container app.
• Create a backend pool that targets your container app.
• Select Add a Backend pool
• Select No to Add backend pool without targets
• Target type – Select IP address or FQDN.
• Target – copy the Application Url from the Overview window of the Container App and remove the https://
• Select Add

• Click on Next: Configuration tab
• Select Add a routing rule
• Enter the name
• Enter priority 1
• Under the Listener tab, Enter Listener name
• In Frontend IP – Select Public
• Protocol – Pick HTTPS. HTTP can be chosen if you don’t have a certificate
• Select Basic for Listener Type
• Error page URL – Leave as No

• Toggle to the Backend Targets tab
• Target type – Select the backend pool that is created earlier
• Backend settings – Select Add new
• Enter Backend settings name, Backend protocol – select HTTP
• Select Yes for Override with a new hostname
• Select Pick hostname from the backend target
• Select Add,

• In Add a routing rule tab click on Add multiple targets to create a path-based rule
• For Path, type /images/*.
• For the Target name, type Images.
• select backend Setting
• For the Backend target, select Images.

• Select Add to save the path rule and return to the Add a routing rule
• Repeat to add another rule for images1.
• Select Add to add the routing rule and return to the Configuration
• Select Next: Tags and then Next: Review + Create.
• In the Overview tab of the application gateway, copy the public IP address and paste it into the browser.
• Change the URL to http://<ip-address>:80/images replace the <ip-address> with the public IP address of application gateway
• The listener on port 80 routes the request to the Images backend pool

• Change the URL to http://<ip-address>:80/images1 replace the <ip-address> with the public IP address of application gateway
• The listener on port 80 routes the request to the Images1 backend pool

Comparison between the Azure Container app and AWS ECS

Azure Container App and AWS Elastic Container Service (ECS) are container orchestration platforms, but they have some differences in architecture, deployment, and management.

Conclusion

Hence deploying a container app behind an application gateway as a backend pool can be a powerful solution for modern application delivery and deployment, providing improved performance, scalability, and security for your application.

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