The Compact Muon Solenoid (CMS) experiment heavily relies on the CMSWEB cluster to host critical services for its operational needs. The cluster is deployed on virtual machines (VMs) from the CERN OpenStack cloud and is manually maintained by operators and developers. The release cycle is composed of several steps, from building RPMs to their deployment, validation, and integration tests. To enhance the sustainability of the CMSWEB cluster, CMS decided to migrate its cluster to a containerized solution based on Docker and orchestrated with Kubernetes (K8s). This allows us to significantly speed up the release upgrade cycle, follow the end-to-end deployment procedure, and reduce operational cost. In this paper, we give an overview of the CMSWEB VM cluster and the issues we discovered during this migration. We discuss the architecture and the implementation strategy in the CMSWEB Kubernetes cluster. Even though Kubernetes provides horizontal pod autoscaling based on CPUs and memory, in this paper, we provide details of horizontal pod autoscaling based on the custom metrics of CMSWEB services. We also discuss automated deployment procedure based on the best practices of continuous integration/continuous deployment (CI/CD) workflows. We present performance analysis between Kubernetes and VM based CMSWEB deployments. Finally, we describe various issues found during the implementation in Kubernetes and report on lessons learned during the migration process.

Compact Muon Solenoid (CMS) 实验在很大程度上依赖于 CMSWEB 集群来托管关键服务以满足其运营需求。集群部署在来自 CERN OpenStack 云的虚拟机 (VM) 上，并由操作员和开发人员手动维护。发布周期由几个步骤组成，从构建 RPM 到其部署、验证和集成测试。为了增强CMSWEB集群的可持续性，CMS决定将其集群迁移到基于Docker并与Kubernetes（K8s）进行编排的容器化解决方案。这使我们能够显着加快版本升级周期，遵循端到端的部署程序，并降低运营成本。在本文中，我们概述了 CMSWEB 虚拟机集群以及我们在迁移过程中发现的问题。我们讨论了 CMSWEB Kubernetes 集群中的架构和实现策略。尽管 Kubernetes 提供了基于 CPU 和内存的水平 pod 自动缩放，但在本文中，我们提供了基于 CMSWEB 服务的自定义指标的水平 pod 自动缩放的详细信息。我们还讨论了基于持续集成/持续部署 (CI/CD) 工作流最佳实践的自动化部署过程。我们展示了 Kubernetes 和基于 VM 的 CMSWEB 部署之间的性能分析。最后，我们描述了在 Kubernetes 中实施过程中发现的各种问题，并报告了迁移过程中的经验教训。我们提供了基于 CMSWEB 服务的自定义指标的水平 pod 自动缩放的详细信息。我们还讨论了基于持续集成/持续部署 (CI/CD) 工作流最佳实践的自动化部署过程。我们展示了 Kubernetes 和基于 VM 的 CMSWEB 部署之间的性能分析。最后，我们描述了在 Kubernetes 中实施过程中发现的各种问题，并报告了迁移过程中的经验教训。我们提供了基于 CMSWEB 服务的自定义指标的水平 pod 自动缩放的详细信息。我们还讨论了基于持续集成/持续部署 (CI/CD) 工作流最佳实践的自动化部署过程。我们展示了 Kubernetes 和基于 VM 的 CMSWEB 部署之间的性能分析。最后，我们描述了在 Kubernetes 中实施过程中发现的各种问题，并报告了迁移过程中的经验教训。