Migrate from using ELB to ALB Load Balancer Type for DCR

[ioannakok]

In DCR we are currently using ELB (Classic Load Balancer) which will probably be deprecated in the near future.

dotcom-rendering/dotcom-rendering/cdk/lib/dotcom-rendering.ts

Lines 89 to 97 in cea44e3

	/**
	* TODO - migrate this ELB (classic load balancer) to an ALB (application load balancer)
	* @see https://github.com/guardian/cdk/blob/512536bd590b26d9fcac5d39329e8217103d7859/src/constructs/loadbalancing/elb.ts#L24-L46
	*
	* GOTCHA: The load balancer name appends `-ELB` when the `app = "rendering"` for backwards compatibility
	* We removed this to avoid the `LoadBalancerName.length > 32`. This will be fixable once we migrate to ALBs.
	*/
	const loadBalancerName = app === 'rendering' ? `${stack}-${stage}-${app}-ELB` : `${stack}-${stage}-${app}`;
	const loadBalancer = new GuClassicLoadBalancer(

The DevX recommendation is to use GuClassicLoadBalancer only when migrating an existing stack and need to retain the load balancer. This was done in #8566

This ticket is to migrate from using ELB to ALB Load Balancer Type. As load balancer is a stateful resource and replacement is unexpected, we need to follow the DevX Migration Guide.

Useful docs

• AWS migration guide
• Good blogpost on the differences between ELB and ALB.

Metric

What metric should we use to evaluate this change?

[cemms1]

Reopening as we still need to do the switch in frontend guardian/frontend#26789 before traffic starts using the new article load balancer

[cemms1]

Moving this to blocked as we want to wait until scaling optimisations are included before we start pointing traffic to the new app

See release plan for details https://docs.google.com/document/d/1EK-tS0NP0yhuuEl_kM9mBPvmwaWH3r3UTcsVLy-WXm0/edit?usp=sharing

[cemms1]

Closing as this has been done in guardian/frontend#26821 and VPC config adjusted suitably in https://github.com/guardian/platform/pull/1575