Our team is debating whether to host our Jenkins controller on a standard AWS EC2 instance or move it into an Amazon EKS cluster. We are worried about the maintenance overhead of Kubernetes versus the vertical scaling limits of a single EC2 instance. For a team handling over 500 builds a day, which cloud-native approach offers better stability and long-term cost-efficiency?
3 answers
Stick with EC2 if your team isn't comfortable with K8s yet. A well-configured Jenkins controller on EC2 with auto-scaling agents works fine.
For 500 builds a day, EKS is the clear winner for scalability. By using the Jenkins Kubernetes plugin, you can treat your agents as ephemeral pods that disappear after the job finishes. This prevents "plugin bloat" and resource contention on the controller. While the initial setup of EKS is more complex due to RBAC and VPC networking, the long-term maintenance is lower because you aren't managing persistent VMs for agents. EC2 is easier to start with but usually leads to a "snowflake server" that is hard to replicate if it ever goes down.
Have you considered using Fargate with EKS to remove the need to manage the underlying EC2 nodes for your Jenkins agents?
David, Fargate is excellent for small tasks, but for heavy builds like Docker-in-Docker (DinD), we found it a bit restrictive. We opted for EKS managed node groups with Spot Instances. This gave us the cost savings of Fargate but with more control over the container runtime. It lowered our monthly AWS bill by nearly 40% compared to our old persistent EC2 agent fleet while still supporting our complex microservices builds.
Linda makes a valid point regarding the learning curve. If you don't have a dedicated DevOps team to manage the cluster, EC2 is a safer bet to avoid downtime.