AWS ALB v. HAProxy/Keepalived on EC2s

To determine whether provisioning your own high-availability (HA) application load balancer using HAProxy and Keepalived on EC2 nodes offers significant cost savings compared to using AWS Application Load Balancer (ALB), we need to compare the costs, operational overhead, and trade-offs of both approaches. Below is a detailed analysis based on available information, including cost estimates, performance considerations, and management requirements.

1. Cost Breakdown

AWS Application Load Balancer (ALB) Costs

AWS ALB pricing consists of two main components: - Hourly Charge: $0.0225 per ALB-hour (as of the latest AWS pricing in 2023, though prices may vary by region). For a month (assuming 730 hours), this is approximately $16.43/month per ALB. - Load Balancer Capacity Units (LCUs): Charged at $0.008 per LCU-hour. LCUs are calculated based on the maximum of: - New connections per second - Active connections - Processed bytes (GB per hour) - Rule evaluations

Example ALB Cost Estimate: - For a moderate workload (e.g., 49 GB/hour of processed data, as in a use case from 2020), the LCU cost is approximately: - 49 LCUs × $0.008 × 24 hours × 30 days = $282.24/month. - Adding the hourly charge: $282.24 + $16.43 = ~$298.67/month for one ALB.[](https://cloudsoft.io/blog/aws-alb-cost-estimation) - For lighter workloads (e.g., 1 GB/hour), the LCU cost drops significantly, potentially to ~$20–$50/month total. - High-traffic applications (e.g., millions of requests/day) could see costs exceeding $500/month due to higher LCU usage.

Additional Notes: - ALB automatically scales across multiple Availability Zones (AZs), ensuring high availability without additional setup. - Data transfer costs within the same AWS region (e.g., between EC2 and ALB) are free for ALB.[](https://cloudsoft.io/blog/aws-alb-cost-estimation) - If you need multiple ALBs (e.g., for different applications or regions), costs scale linearly.

HAProxy/Keepalived on EC2 Costs

Running HAProxy with Keepalived on EC2 requires provisioning at least two EC2 instances for high availability (one master, one backup) and managing an Elastic IP (EIP) for failover. Costs include:

Example HAProxy/Keepalived Cost Estimate: - Low Workload: Two t3.micro instances + one EIP + minimal data transfer (e.g., 100 GB/month): - EC2: $15.18/month - EIP: $0 - Data transfer: ~$2 - Total: ~$17.18/month - Moderate Workload: Two t3.medium instances + one EIP + 1 TB data transfer: - EC2: $60.74/month - EIP: $0 - Data transfer: $20 - Total: ~$80.74/month - High Workload: Two m5.large instances + one EIP + 10 TB data transfer: - EC2: $140.16/month - EIP: $0 - Data transfer: $200 - Total: ~$340.16/month

Comparison (Monthly Costs): | Workload | ALB Cost | HAProxy/Keepalived Cost | Savings with HAProxy | |----------------|----------|-------------------------|----------------------| | Low (100 GB) | ~$30–50 | ~$17.18 | ~$12–33 | | Moderate (1 TB)| ~$298.67 | ~$80.74 | ~$217.93 | | High (10 TB) | ~$500+ | ~$340.16 | ~$160+ (varies) |

Key Observations: - For low to moderate workloads, HAProxy/Keepalived can offer significant savings (up to 70–80% for moderate traffic) due to lower instance costs and no LCU charges.[](https://8kmiles.com/blog/comparison-analysis-amazon-elb-vs-haproxy-ec2/) - For high workloads, savings diminish because EC2 instance costs scale with traffic (requiring larger instances) and data transfer costs become significant. ALB’s LCU-based pricing may be more predictable for very high traffic. - A 2013 analysis estimated that two m1.large instances for HAProxy cost ~$387/month vs. ~$26/month for ELB (Classic), but this is outdated due to cheaper modern instances (e.g., t3/m5) and ALB’s LCU pricing.[](https://8kmiles.com/blog/comparison-analysis-amazon-elb-vs-haproxy-ec2/)

2. Operational Overhead and Trade-offs

ALB

Advantages: - Managed Service: AWS handles scaling, security patches, high availability across AZs, and SSL certificates (via ACM). Minimal setup and maintenance.[](https://stackoverflow.com/questions/67244375/haproxy-vs-alb-or-any-other-load-balancer-which-one-to-use) - Auto-Scaling: Automatically adjusts to traffic spikes, including sudden surges (with pre-warming for known spikes).[](https://8kmiles.com/blog/comparison-analysis-amazon-elb-vs-haproxy-ec2/) - Integration: Seamless integration with AWS services (e.g., Auto Scaling, CloudWatch, ECS, EKS, Route 53). - Features: Supports WebSockets, HTTP/2, sticky sessions, and advanced routing (e.g., path-based, host-based).[](https://www.f5.com/company/blog/nginx/aws-alb-vs-nginx-plus) - Uptime: 99.95% SLA, reducing downtime risks.[](https://stackoverflow.com/questions/68067299/pricing-for-aws-application-load-balancer-vs-nginx-load-balancer-setup-on-amazon)

Disadvantages: - Cost: LCU pricing can be unpredictable for high-traffic or volatile workloads.[](https://cloudsoft.io/blog/aws-alb-cost-estimation) - Limited Customization: Less flexibility for advanced load balancing algorithms or custom configurations compared to HAProxy.[](https://www.peerspot.com/products/comparisons/amazon-elastic-load-balancing_vs_haproxy) - No Fixed IPs: ALB doesn’t provide static IPs, which can be an issue for whitelisting in external firewalls (NLB is an alternative here).[](https://8kmiles.com/blog/comparison-analysis-amazon-elb-vs-haproxy-ec2/)

HAProxy/Keepalived on EC2

Advantages: - Cost Savings: Significantly cheaper for low to moderate traffic, especially with small instances.[](https://stackoverflow.com/questions/67244375/haproxy-vs-alb-or-any-other-load-balancer-which-one-to-use) - Customization: HAProxy supports advanced algorithms (e.g., least connections, URI-based), ACLs, rate limiting, and SSL/TLS termination.[](https://www.peerspot.com/products/comparisons/amazon-elastic-load-balancing_vs_haproxy)[](https://dzone.com/articles/implementing-load-balancer-using-haproxy-on-aws) - Flexibility: Can be tailored to specific needs (e.g., TCP/HTTP proxying, content switching).[](https://stackshare.io/stackups/haproxy-vs-keepalived) - Static IPs: Using EIPs allows whitelisting for external firewalls.[](https://8kmiles.com/blog/comparison-analysis-amazon-elb-vs-haproxy-ec2/) - Open-Source: No vendor lock-in, and HAProxy is widely used and battle-tested.[](https://www.peerspot.com/products/comparisons/amazon-elastic-load-balancing_vs_haproxy)

Disadvantages: - Operational Overhead: You must manage EC2 instances, including: - Installing and updating HAProxy and Keepalived. - Configuring VRRP for failover (AWS doesn’t support multicast, requiring unicast setups).[](https://www.rapid7.com/blog/post/2014/12/03/keepalived-and-haproxy-in-aws-an-exploratory-guide/)[](https://www.haproxy.com/blog/haproxy-on-aws-best-practices-part-3) - Monitoring instance health and scaling manually or via automation scripts. - Applying security patches and managing SSL certificates. - Scaling: Unlike ALB, scaling HAProxy requires provisioning additional EC2 instances, which involves automation (e.g., Auto Scaling groups) or manual intervention.[](https://8kmiles.com/blog/comparison-analysis-amazon-elb-vs-haproxy-ec2/) - Failover Complexity: Keepalived uses VRRP to reassign EIPs during failover, which takes ~5–30 seconds, slower than ALB’s near-instant failover.[](https://serverfault.com/questions/495224/haproxy-and-keepalived-on-amazon-ec2) - Expertise: Requires deeper knowledge of HAProxy configuration, Keepalived, and AWS networking (e.g., VPCs, ENIs).[](https://www.peerspot.com/products/comparisons/amazon-elastic-load-balancing_vs_haproxy) - Downtime Risk: Misconfigurations or delays in EIP reassignment could lead to downtime, unlike ALB’s managed reliability.[](https://serverfault.com/questions/495224/haproxy-and-keepalived-on-amazon-ec2)

3. Performance Considerations

4. Use Case Recommendations

Choose ALB When: - You prioritize ease of use, minimal maintenance, and tight AWS integration. - Your application requires advanced AWS features (e.g., ECS/EKS integration, WAF, CloudWatch metrics). - You expect highly variable or unpredictable traffic spikes. - Downtime is unacceptable, and you lack the expertise to manage HAProxy/Keepalived. - Budget allows for higher costs (e.g., >$100/month for moderate traffic).

Choose HAProxy/Keepalived When: - You have low to moderate traffic and want to minimize costs (e.g., <1 TB/month data transfer). - You need advanced customization (e.g., specific load balancing algorithms, ACLs, or TCP proxying). - You require static IPs for external firewall whitelisting. - You have the expertise and resources to manage EC2 instances, HAProxy, and Keepalived. - You’re comfortable with slightly slower failover (seconds vs. near-instant) and can automate scaling.

Hybrid Approach: - Some setups use HAProxy behind ALB for a balance of customization and managed reliability, though this increases costs and complexity.[](https://www.haproxy.com/blog/haproxy-amazon-aws-best-practices-part-1)

5. Recent Trends and Considerations (2025)

6. Conclusion

Are there significant cost savings? - Yes, for low to moderate workloads: HAProxy/Keepalived on EC2 can save 50–80% compared to ALB, especially for traffic under 1 TB/month. For example, a moderate workload might cost ~$80/month vs. ~$300 for ALB.[](https://cloudsoft.io/blog/aws-alb-cost-estimation) - No, for high workloads or low-maintenance needs: Savings diminish with high traffic due to EC2 scaling and data transfer costs, and ALB’s managed nature reduces operational risks and effort.

Recommendation: - For small projects or startups with predictable traffic and technical expertise, HAProxy/Keepalived is a cost-effective choice. Start with t3.micro or t4g.micro instances and monitor performance. - For enterprise or high-traffic applications, ALB is often worth the cost due to its scalability, reliability, and minimal maintenance. If customization is critical, consider a hybrid approach or evaluate AWS Network Load Balancer (NLB) for static IPs. - Always prototype and benchmark both setups for your specific workload, using tools like AWS Cost Explorer or custom monitoring to validate costs and performance.

If you provide specific workload details (e.g., expected traffic, request rates, or application type), I can refine the cost estimates further. Would you like me to do so?