KubeCon + CloudNativeCon Japan 2025

Everyone is talking about platform engineering. You see smooth demos of golden paths and self-service platforms. However, there’s a significant area of challenges that is less talked about and thus often neglected when designing developer platforms.

In this talk, we’ll explore the often-overlooked day 2 challenges that platform teams face. We’ll dissect the area of day 2 into the many sub-areas and challenges they pose. Drawing on real-world experiences, including notable migrations that many in this community have faced, we'll shed light on the pain behind developer platforms and discuss solutions to these issues. Among others, we’ll delve into practical strategies for managing versioning and rollouts, and highlight the significant hurdles encountered, such as dependencies on end user teams or GitOps.

Join us for insights, strategies, and stories from the trenches that will help you navigate the complexities of service iteration in developer platforms.

Kubernetes is widely recognized as a platform for building platforms, but even with modern platform engineering techniques, managing an end-to-end release and deployment lifecycle remains challenging.

This talk will first analyze key pain points in platform engineering and propose a new perspective on infrastructure code by separating different personas’ views. We advocate for a tenant-centric API that prioritizes user experience—minimizing input, reducing learning curves, and abstracting cloud provider details to decouple desired resources from underlying specs.

Next, we’ll introduce a design for fanning out tenant resource claims, enhancing flexibility and extensibility through a code generation component and a Kubernetes-like labeling system. Finally, we’ll cover the glue that binds everything together: Pkl for templating and validation, Prow for GitHub event-driven automation, and Crossplane + ArgoCD as the claim realization engine.

As organizations scale their Kubernetes adoption, multi-cluster architectures are becoming the backbone of resilience, scalability, and compliance. However, building a unified developer experience across these clusters while abstracting operational complexities is a significant challenge.
In this session we’ll demonstrate how Cluster-API (CAPI), a declarative tool for Kubernetes lifecycle management and Linkerd, the powerful yet lightweight service mesh, can work together to simplify multi-cluster topologies for Internal Developer Platforms (IDP). By combining CAPI's robust cluster management with Linkerd’s seamless cross-cluster service communication, platform teams can deliver a streamlined and intuitive experience for developers, enabling them to focus on building and deploying applications without worrying about underlying infrastructure.

You probably have more than one cluster and there is a decent chance you are using Argo CD. Additionally, it is quite likely that you have a few other variations of Kubernetes cluster lists. We posit that writing glue code to stitch together these clusters lists is not an awesome use of your time. Thankfully the good folks in SIG-Multicluster built this super cool api for cluster lists, cluster profile/cluster inventory! We are going to show you how to use said fancy new list with Argo CD along with other multi-cluster tools across Kubernetes clusters hosted by different providers. There will be demos. Possibly Mustaches. And a decent amount of awful puns. So come on down to bear witness to some sweet multi-cluster abstractions that will surely get your heart rate up.

Platform Engineering enables developers to focus on business value-aligned tasks by providing internal developer platforms (IDPs) that automate non-essential tasks. Kubernetes is widely used as a foundation for IDPs thanks to its scalability and flexibility.

However, Kubernetes was designed as a general workload orchestrator, not a platform component. As a result, IDP builders must integrate additional Cloud Native technologies and customizations, which can create scalability bottlenecks. At LY Corporation, his team has developed a Kubernetes-based, multi-tenant IDP running over 140K pods, and they faced such scalability challenges.

In this session, he will discuss scalability bottlenecks faced in the IDP, including observability pipelines, access control, etc. He will also explore scaling strategies for IDPs and how they address real-world scalability issues. By the end of this session, you will gain deeper insights into scalability challenges from a platform builder’s perspective.