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ALB Low Traffic Remediation Tutorial

Overview​

This tutorial demonstrates how to consolidate multiple low-traffic Application Load Balancers into a single ALB using host-based routing, reducing monthly costs by eliminating redundant ALB base charges.

Remediation Action: Consolidate Target Service: Application Load Balancer (ALB) Estimated Cost Savings: ~$16.43/month per consolidated ALB

Step 1: Identify Low-Traffic ALB​

Navigate to the Load Balancers console to identify ALBs with low traffic. The remediation-alb-low-traffic-alb is serving minimal requests and is a candidate for consolidation.

Load Balancers List

Step 2: View ALB Details​

Click on the ALB name to view its configuration. Note the DNS name and listeners that will need to be replicated on a consolidated ALB.

ALB Details

Step 3: Check Current Listeners​

Review the Listeners tab to understand the current routing configuration. For consolidation, you'll recreate these as host-based rules on a shared ALB.

Listeners Tab

Step 4: Review Target Groups​

Identify the target groups associated with this ALB. These will be retained and pointed to by new routing rules on the consolidated ALB.

Step 5: Navigate to CloudWatch Metrics​

Check the Monitoring tab to confirm low traffic. Look for RequestCount metrics showing <100 requests/hour over the past 7 days, validating this as a consolidation candidate.

Monitoring Metrics

Step 6: Plan Consolidation Architecture​

Consolidation Strategy​

For this low-traffic ALB, the consolidation approach is:

  1. Identify or create a primary ALB to receive consolidated traffic
  2. Add host-based routing rules - Create listener rules like Host: app.example.com → Target Group A
  3. Update DNS records - Point application domains to the consolidated ALB
  4. Test thoroughly - Verify traffic routing before deletion
  5. Delete the low-traffic ALB - Remove after confirming no traffic

Example routing configuration:

Consolidated ALB
├── Rule: Host = app1.example.com → Target Group A (from old ALB #1)
├── Rule: Host = app2.example.com → Target Group B (from old ALB #2)
└── Default → Target Group Default

Step 7: Create Host-Based Routing Rule (Demo)​

On your consolidated ALB (or create one if needed), navigate to the Listeners tab to add host-based routing rules.

Step 8: Add Listener Rule​

Click "View/edit rules" on the listener, then "Add rule" to create a host-based routing rule that directs traffic to the existing target group.

Step 9: Configure Host Condition​

Add a condition for "Host header" matching your application's domain (e.g., app.example.com). This routes traffic based on the requested hostname.

Step 10: Configure Forward Action​

Set the action to "Forward to" and select the target group from the low-traffic ALB. This preserves existing backend routing.

Step 11: Update DNS Records​

Update DNS​

In your DNS provider (Route 53, etc.), update the CNAME or A record for your application domain:

Before:

app.example.com → remediation-alb-low-traffic-alb-1414231821.us-east-1.elb.amazonaws.com

After:

app.example.com → consolidated-alb-123456789.us-east-1.elb.amazonaws.com

Wait for DNS propagation (typically 5-60 minutes depending on TTL).

Step 12: Verify Traffic Routing​

Test the application to confirm traffic is routing correctly through the consolidated ALB:

curl -H "Host: app.example.com" http://consolidated-alb-123456789.us-east-1.elb.amazonaws.com

Monitor target group health and CloudWatch metrics on the consolidated ALB.

Step 13: Monitor Consolidated ALB​

Monitor the consolidated ALB for 24-48 hours to ensure stable operation. Check:

  • Target health status remains healthy
  • Request count matches expected traffic
  • No increase in 4xx/5xx errors

Step 14: Delete Low-Traffic ALB​

Once traffic has been successfully migrated and verified, return to the Load Balancers console to delete the unused ALB.

Step 15: Select ALB for Deletion​

Select the low-traffic ALB that has been replaced. Confirm no traffic is being served before proceeding.

Select ALB for Deletion

Step 16: Delete ALB​

Click Actions > Delete load balancer. This immediately stops billing for the ALB base charge (~$16/month savings per ALB).

Delete ALB

Step 17: Confirm Deletion​

Confirm the deletion. The ALB will be removed within a few minutes. Target groups are preserved and remain attached to the consolidated ALB.

Confirm Deletion

Step 18: Verify Deletion​

The ALB has been successfully deleted. The load balancer list no longer shows the low-traffic ALB, confirming cost savings are now active.

Deletion Verified

Cost Impact​

Each consolidated ALB saves approximately $16.43/month in base charges. Consolidating 5 low-traffic ALBs into 1 ALB yields $65.72/month savings ($788.64/year). LCU charges may increase slightly on the consolidated ALB but are typically minimal compared to base cost savings.

Alternative Approaches​

  • API Gateway: For simple HTTP/HTTPS APIs with low traffic, consider API Gateway pay-per-request pricing instead of ALB
  • CloudFront + Lambda@Edge: For static content or edge routing, CloudFront can eliminate ALB entirely
  • Path-based routing: Instead of host-based routing, use path patterns (e.g., /app1/*, /app2/*) if multiple apps can share a domain
  • Classic Load Balancer migration: If using CLBs, migrate to ALB for cost savings and better features before consolidation
  • Do nothing: If ALBs require network isolation for security/compliance, consolidation may not be appropriate

Summary​

This tutorial demonstrated how to identify, consolidate, and delete low-traffic Application Load Balancers to reduce AWS costs. By using host-based routing on a shared ALB, you can eliminate redundant base charges while maintaining application functionality.