Problems with Configuring Elastic Load Balancer for Elastic Beanstalk Application

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Introduction

Elastic Beanstalk is a popular service provided by Amazon Web Services (AWS) that allows developers to deploy and manage applications easily. One of the key features of Elastic Beanstalk is its ability to automatically scale the application based on the incoming traffic. To achieve this, Elastic Beanstalk uses Elastic Load Balancer (ELB) to distribute the traffic evenly across multiple instances of the application.

However, configuring the Elastic Load Balancer for an Elastic Beanstalk application can sometimes be a challenging task. In this blog post, we will discuss some common problems that developers face while configuring the Elastic Load Balancer and provide solutions for them.

Configuring the Load Balancer Timeout

By default, the load balancer timeout for an Elastic Beanstalk application is set to 60 seconds. This means that if the application takes longer than 60 seconds to respond, the load balancer will terminate the request. This can be a problem if your application performs long-running tasks or has complex operations that take more time.

To handle such scenarios, you need to increase the load balancer timeout. This can be done by modifying the Elastic Beanstalk configuration file (.ebextensions) in your application. Add the following lines to increase the timeout to 180 seconds:

option_settings:
  aws:elasticbeanstalk:environment:process:default:timeout: 180

Make sure to redeploy your application after making this change. With the increased timeout, your application will have more time to respond to requests, and you will no longer face the issue of requests being terminated by the load balancer.

Handling HTTPS Traffic

If you want to secure your Elastic Beanstalk application with HTTPS, you can do so by configuring the load balancer to terminate SSL connections. This means that the load balancer will handle the SSL encryption and decryption and forward the traffic to the instances in plain HTTP. To configure HTTPS for your application, follow these steps:

  1. Generate an SSL certificate for your domain. You can either use a self-signed certificate or obtain a certificate from a trusted certificate authority.
  2. Upload the SSL certificate to AWS Certificate Manager (ACM). ACM is a service provided by AWS that manages SSL certificates.
  3. Open the Elastic Beanstalk management console and navigate to your application.
  4. In the left navigation panel, click on "Configuration".
  5. Under "Load Balancer", click on "Edit".
  6. In the "Listener" section, click on "Add listener".
  7. Select "HTTPS" as the protocol and choose the SSL certificate that you uploaded to ACM.
  8. Click on "Add" to save the changes.

Once the changes are saved, your Elastic Beanstalk application will be accessible over HTTPS. The load balancer will handle the SSL encryption and decryption, ensuring that the communication between the client and the load balancer is secure.

Configuring Sticky Sessions

Sticky sessions allow the load balancer to direct multiple requests from the same client to the same instance. This is useful when your application relies on session data and needs to maintain the state between requests.

To enable sticky sessions for your Elastic Beanstalk application, follow these steps:

  1. Open the Elastic Beanstalk management console and navigate to your application.
  2. In the left navigation panel, click on "Configuration".
  3. Under "Load Balancer", click on "Edit".
  4. In the "Sticky sessions" section, choose "Enable".
  5. Select the desired session stickiness method. The available options are:
    • Application-controlled: The load balancer determines the sticky session based on the application cookies.
    • Instance-controlled: The load balancer determines the sticky session based on the instance ID.
  6. Click on "Apply" to save the changes.

After enabling sticky sessions, the load balancer will route multiple requests from the same client to the same instance. This ensures that the session data is preserved, and your application can maintain the state between requests.

Configuring Health Checks

Health checks are used by the load balancer to determine the health of the instances in an Elastic Beanstalk environment. If an instance fails the health check, the load balancer will stop sending traffic to that instance until it becomes healthy again.

By default, Elastic Beanstalk configures health checks based on the response code received from the instances. If an instance returns a non-200 response code, it is considered unhealthy. However, sometimes your application may return non-200 response codes for valid reasons, such as redirection or authentication challenges.

To configure health checks with custom rules, follow these steps:

  1. Open the Elastic Beanstalk management console and navigate to your application.
  2. In the left navigation panel, click on "Configuration".
  3. Under "Load Balancer", click on "Edit".
  4. In the "Health check" section, click on "Enable customized health check".
  5. Enter the desired values for the health check URL and other parameters.
  6. Click on "Apply" to save the changes.

With custom health checks, you can configure the load balancer to consider instances as healthy based on specific criteria. This allows you to handle non-200 response codes from your application without affecting the health of the instances.

Conclusion

Configuring the Elastic Load Balancer for an Elastic Beanstalk application can be a complex task. However, by following the steps mentioned in this blog post, you can overcome common problems and ensure that your application runs smoothly. Remember to adjust the load balancer timeout, configure HTTPS traffic, enable sticky sessions, and set up custom health checks based on your application's requirements.