CoreDNS is a lightweight, extensible DNS server and the default service discovery mechanism in Kubernetes clusters. As a CNCF graduated project, CoreDNS uses a flexible plugin-based architecture that allows dynamic updates based on the cluster state. This design helps teams handle large-scale DNS requests reliably with minimal overhead, providing a consistent way to manage service discovery and DNS-based traffic policies in modern deployments.

However, self-managed CoreDNS upgrades can present significant challenges – from dealing with plugin compatibility and deprecated Corefile directives to ensuring there’s no disruption in cluster-wide DNS resolution. In this blog, we highlight how Chkk’s Operational Safety Platform simplifies CoreDNS upgrades, covering everything from curated release notes and automated checks, to comprehensive Upgrade Templates.

Chkk’s Coverage for CoreDNS

Curated Release Notes

Chkk continuously monitors official CoreDNS release notes and flags new features, plugin changes, or deprecations relevant to your environment. Instead of manually sifting through lengthy release documentation, you receive concise, actionable summaries of the changes that matter most. By surfacing these critical details, Chkk helps you avoid unexpected DNS failures caused by unseen breaking changes and allows you to plan upgrades with confidence.

Preflight & Postflight Checks

Before you upgrade, Chkk performs rigorous preflight checks to ensure your CoreDNS configuration and cluster are ready. It checks for incompatible Corefile syntax, deprecated plugins, or other risk factors that might cause your DNS pods to crash after an update. Once you’ve upgraded CoreDNS, Chkk runs postflight checks to verify that the new CoreDNS pods are healthy and serving DNS properly. This automated pre/post-check process catches issues like syntax errors, plugin mismatches, or resource constraints early, so you can fix them before they impact your applications.

Version Recommendations

Chkk actively tracks CoreDNS versions and correlates them with your Kubernetes release and security advisories. It alerts you when your current CoreDNS version is outdated, nearing end-of-life, or missing critical patches. You’ll receive clear recommendations for stable versions to upgrade to, taking into account Kubernetes compatibility, security fixes, and plugin maturity. If you’ve pinned your cluster to an older CoreDNS release, Chkk will flag it with warnings about known vulnerabilities or EOL status. This means you can keep your DNS component on a well-supported version at all times and avoid running software that’s fallen out of support.

Upgrade Templates

Chkk offers structured Upgrade Templates tailored for CoreDNS, supporting two key methods:

• In-place Upgrades: Update existing CoreDNS pods in a rolling fashion, sequentially transitioning pods to the new version while ensuring minimal disruption to DNS services.
• Blue-Green Deployments: Deploy a parallel set of CoreDNS pods running the new ("green") version alongside your current ("blue") pods, validate DNS responses and stability, and seamlessly shift traffic over when ready, significantly reducing downtime and providing straightforward rollback options.

Each template includes clearly documented steps, built-in health checks, and rollback procedures, ensuring predictable, controlled CoreDNS upgrades without guesswork or unexpected downtime.

Preverification

For major CoreDNS releases or any time you want extra assurance, Chkk offers preverification to dry-run the upgrade in a controlled setting. This feature simulates your CoreDNS upgrade on a digital twin of your cluster, using your actual Corefile and configuration. During the simulation, Chkk validates your Corefile against the new CoreDNS version and flags any issues like deprecated directive usage, plugin incompatibilities, or performance bottlenecks that would appear after the upgrade. By catching these problems before you apply changes to production, you can address them proactively. 

Supported Packages

No matter how you deploy CoreDNS, Chkk has you covered. The platform is compatible with the official CoreDNS Helm chart, Kustomize configurations, and even plain Kubernetes YAML deployments. Chkk recognizes custom CoreDNS container images, private registry sources, and non-standard deployment patterns as well. This flexibility means you don’t have to change your preferred installation method – Chkk’s intelligence adapts to your setup. 

Chkk’s Core Benefits

Chkk Operational Safety Platform simplifies upgrades, reduces risk, and keeps your Kubernetes infrastructure operational. Here’s how that applies to CoreDNS upgrades:

• Speed Up and De-Risk Upgrades: Manually upgrading CoreDNS is time-consuming. Chkk accelerates the process and makes it safer by generating a detailed Upgrade Plan for each cluster. This plan spans all components—control plane, node versions, add-ons, and dependencies—and flags required changes, including recommended add-on versions or deprecated APIs. Instead of piecing together requirements from various release notes, teams receive a clear and actionable upgrade path. Chkk’s automation can cut upgrade preparation time by 3-5x, reducing weeks of planning to just days.
• Eliminate Redundant Effort: Many organizations squander countless hours on repetitive upgrade planning and research. By unifying upgrade workflows across teams, Chkk prevents duplication of effort and ensures that insights and processes don’t need to be reinvented with every release. This consolidation of efforts can save thousands of hours.
• Delegate, Parallelize, and Standardize Workflows: Chkk makes it easy to break out upgrade tasks among team members, all while maintaining standardized workflows that reduce confusion and boost efficiency. Engineers spend less time context-switching, and institutional knowledge is retained and shared effectively. During staff turnover or organizational changes, having a historical record of upgrade best practices prevents delays.
• Enhance Operational Safety: Kubernetes upgrades introduce inherent risk, but Chkk helps you detect and fix potential problems before they cause disruptions. With automated risk detection, your team can prevent hundreds of potential breakages annually—for every hundred clusters—saving significant break-fix effort. By focusing on proactive measures, you can innovate rather than constantly firefighting.

Simplify Upgrades for CoreDNS and 100s of Other Kubernetes Add-ons

Try Chkk Upgrade Copilot to experience how these extended capabilities can simplify your upgrade processes for CoreDNS and 100s of other Kubernetes Add-ons, Application Services, and Open Source Projects. We look forward to helping you achieve seamless, secure, and efficient operations. 

Click below to start for free or book a demo to learn more.