Kubernetes (K8s) is today the go-to standard for orchestrating application containers. It lets organizations deploy, manage, and scale their applications with greater scalability, advanced automation, and strong resilience.
However, a poorly controlled Kubernetes migration can lead to cost overruns, service interruptions, and involves a number of technical challenges that are important to keep in mind. The transition to Kubernetes is not just about moving workloads onto a new platform: it involves a deep transformation of the IT infrastructure, has an impact on technical teams, and requires a methodical approach.
This article recaps the benefits of migrating to Kubernetes, then describes the main challenges to anticipate and how to make this transition securely and effectively.
Why Migrate to Kubernetes?
We wrote a detailed article on the business benefits of Kubernetes and the difficulties to anticipate before carrying out a K8s migration.
In (very) short, companies adopt Kubernetes to:
- Modernize their infrastructure by replacing monolithic solutions with a Cloud Native architecture;
- Gain scalability and resilience through automatic container orchestration and native self-healing mechanisms that ensure service continuity;
- Reduce infrastructure costs by optimizing resource consumption with vertical and horizontal auto-scaling;
- Limit vendor lock-in by improving portability and interoperability, since Kubernetes is agnostic with respect to cloud providers and can be deployed on-premise as well as in public or private cloud;
- Simplify application deployment and operations with Helm, CI/CD solutions, and GitOps, which enable automated deployments on Kubernetes;
- Streamline application updates and speed up the lifecycle and time-to-market of their applications, with progressive deployment strategies (Canary Release, Blue-Green Deployment, etc.).
The Main Challenges of a Kubernetes Migration
Several challenges need to be addressed, notably choosing the right migration strategy, the type of Kubernetes solution to select, application compatibility, managing persistent storage and databases, securing the Kubernetes cluster, and properly preparing operational management.
Choosing the Right Migration Strategy
Migrating to Kubernetes is not just about moving applications from an existing environment to a new Kubernetes cluster. It’s essential to adopt a strategy suited to the company’s needs and constraints. Several approaches are possible:
Lift & shift consists of moving applications as-is into containers without major modification. This method allows for a fast migration but doesn’t fully leverage Kubernetes’ capabilities and may require post-migration adjustments.
Replatforming involves minor adaptations to better take advantage of Kubernetes features, such as auto-scaling or advanced network and storage management.
Refactoring is a deeper approach in which the application is redesigned to adopt a microservices architecture, which maximizes the benefits of Kubernetes but represents a more substantial development effort.
Progressive migration, where the old infrastructure coexists with the new Kubernetes platform during a transition period. This can help limit risk and adopt Kubernetes in stages.
Making the right choice depends on many factors: application complexity, business objectives, time constraints, available resources, etc. A prior technical audit helps assess the best approach to take.
Choosing the Right K8s Solution and Design
Kubernetes can be deployed in many ways, each with its own advantages and constraints. The first choice to make concerns the type of Kubernetes solutions to use.
Some companies opt for a managed Kubernetes solution offered by a cloud provider, which offers simplified management and native integration with the provider’s services. Others prefer a self-hosted distribution such as Suse Rancher or Red Hat OpenShift in order to retain full control over their infrastructure. Finally, some rely on custom-built Kubernetes solutions such as the one we offer at Enix (based on the excellent Talos), which we can deploy on any type of environment.
Once the Kubernetes solution is chosen, it’s crucial to design an optimal architecture. Several factors need to be taken into account (this list is far from exhaustive):
High availability: Should a multi-zone or multi-region cluster be deployed to ensure service continuity in case of failure?
Multi-cloud and hybridization: Should workloads be allowed to run across multiple on-premise or cloud (public/private) environments to avoid vendor lock-in? This can also help support a disaster recovery (DR) policy;
Security: What network segmentation, authentication, and secrets management policy should be adopted? What complementary mechanisms should be implemented around the Kubernetes cluster?
Resource management: How should Node Pools, affinities, and taints be structured to optimize workload execution? How should auto-scaling be configured?
Monitoring and observability: What tools and code should be integrated at the application level from the cluster build phase and in application design, to monitor their health and performance?
It’s recommended to rely on experienced Kubernetes architects with production experience to define a scalable, secure, and optimized platform from the build phase and throughout the migration. We have repeatedly had to take over and evolve Kubernetes platforms that were poorly designed from the start, with some migrations having in fact failed entirely.
Containerization: Ensuring App Compatibility with K8s
Applications are generally not ready to run on Kubernetes right away. A successful K8s migration requires assessing their compatibility, adapting workloads accordingly, containerizing applications, and finally packaging them (Helm or Kustomize) so they can be easily deployed on Kubernetes.
Monolithic applications, for example, can be difficult to containerize due to their complex dependencies. In some cases, they will need to be refactored into microservices to fully benefit from Kubernetes. In addition, some applications use components that are not designed to run in a distributed environment, which can lead to latency or stability issues.
Another important point is putting in place observability at the application level, a central concept of the Cloud Native approach around Kubernetes.
Managing Persistent Storage and Databases
One of the major challenges of a K8s migration lies in managing storage and databases.
Kubernetes’ architecture is built on ephemeral workloads, where containers can be created, deleted, or moved automatically based on need. This stateless and distributed nature of Kubernetes is not always compatible with persistent data, which requires guaranteed stability and integrity.
The first step is therefore to assess whether it makes sense to host these storage and database components inside the Kubernetes cluster, or whether it’s preferable to keep them outside of it. For a few years now, it has become simpler to bring these functions into Kubernetes, thanks to mechanisms native to Kubernetes and third-party technologies mature enough to run large-scale production databases within clusters.
To address this constraint, Kubernetes offers solutions such as Persistent Volumes (PV) and Persistent Volume Claims (PVC), which decouple storage from applications. But managing databases and stateful workloads in Kubernetes remains a challenge, requiring specific solutions such as StatefulSets, distributed storage (Rook, Longhorn), or Cloud Native databases suited to the task.
Specialized tools like Velero also make migration easier by ensuring secure backup and restoration of data. Likewise, solutions such as Rook or Longhorn make it possible to integrate high-performance native Kubernetes storage.
Securing the Migration and Operation of Kubernetes
Migrating to Kubernetes must not come at the expense of security. As with any technology, a poorly configured Kubernetes cluster can be an entry point for attacks, putting the company’s data and services at risk.
The first step in securing a migration is to restrict access with strict permission control via Role-Based Access Control (RBAC). It’s also essential to protect communication between services by enabling encryption and putting in place Network Policies that define which applications can communicate with each other.
Another concern is container security itself. It’s crucial to scan Docker images before deployment to identify any vulnerabilities. Tools like Trivy or Aqua Security can help automate these checks and reduce risks tied to security flaws.
Finally, to quickly detect any anomaly, integrating monitoring and an alerting system is essential. Solutions such as Falco or Open Policy Agent (OPA) help monitor container activity and identify any suspicious behavior.
Optimizing Performance and Monitoring after Migration
A migration to K8s doesn’t stop once workloads have been moved to the new Kubernetes cluster. It’s essential to optimize the infrastructure from the design stage and continuously thereafter to get the most out of Kubernetes in terms of performance and scalability.
One of the first optimization levers is resource management. Kubernetes offers several auto-scaling mechanisms, notably the Horizontal Pod Autoscaler (HPA), which dynamically adjusts the number of pods based on load, and the Vertical Pod Autoscaler (VPA), which adjusts the resources allocated to each pod. Proper configuration helps avoid resource overconsumption and reduce operating costs.
Workload scheduling also plays a key role in the cluster’s overall performance. Kubernetes allows you to fine-tune pod placement with strategies such as Node Affinity, Taints, and Tolerations, which make it possible to intelligently distribute workloads according to node capacity and application needs.
Finally, continuous monitoring is essential to ensure the cluster is running optimally. Tools such as Prometheus, Grafana, or Loki make it possible to collect metrics, analyze resource consumption, and identify potential bottlenecks. Other solutions such as the Elastic stack and Datadog are also commonly used. Good observability makes it possible to anticipate problems before they affect production and to continuously optimize the Kubernetes infrastructure.
How Can a Provider Make Kubernetes Migration Easier?
To tackle these many technical and organizational challenges with peace of mind, it can be worthwhile to bring in a Kubernetes provider specialized in Cloud Native tools and technologies. They can bring proven methodology, migration experience, as well as the ability to manage complex Kubernetes infrastructures in production.
This Kubernetes expert partner ensures a smooth migration and can enable a faster transition while optimizing Kubernetes operations over the long term. Here are examples of tasks a provider is typically called on to perform as part of comprehensive Kubernetes support:
Auditing the existing environment to define the needs for the new cluster and the most suitable K8s migration strategy: lift & shift, refactoring, replatforming, or progressive migration with coexisting environments;
Design, architecture, and build of the new Kubernetes platform and more broadly the Cloud Native platform: based on existing infrastructure components (integrated with or adjacent to the Kubernetes cluster), the needs of applications hosted on the platform, high-availability and disaster-recovery requirements, and the type of deployment environment chosen (on-premise, private cloud, public cloud, or hybrid)…
Adapting workloads, supporting application containerization so they can be orchestrated by Kubernetes, whether or not a new microservices- and service-mesh-based application architecture is used;
Automating infrastructure and application deployment with packaging technologies like Helm, GitOps technologies like ArgoCD or FluxCD, or cloud and infrastructure deployment technologies like Terraform, Ansible, or Crossplane…
Managing load testing and pre-production validation to guarantee a go-live without service disruption;
Training and supporting your tech teams on Cloud Native tools and technologies (including Kubernetes, of course) to ensure skill development and smooth adoption across Dev, DevOps, and Ops teams alike;
Operational management and 24/7 run and post-migration follow-up: continuous performance monitoring and supervision, ongoing security hardening and optimization, Kubernetes support for deploying new applications or scaling application load, proactive incident management and on-call duty, etc.
Conclusion
Undertaking a migration to Kubernetes is a strategic decision and a key step in modernizing your IT infrastructure. Beyond being a “simple” technical transformation, this migration can positively impact the business by speeding up the development lifecycle of your applications and services while increasing their quality and availability.
This transition must nonetheless be managed with expertise to avoid common pitfalls and meet the challenges discussed in this article. Whether with us at Enix (we’ve been running K8s in production in pretty much every shape and form since the very beginning :) or with another specialized partner, we strongly recommend getting expert support either way. We wish you a smooth migration!
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