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Category: Containers

Unplanned Failover and SQL Server on Kubernetes

Published 2026-04-27 by Kevin Feasel

Anthony Nocentino performs additional testing:

In my planned failover walkthrough, I showed what happens when you deliberately move the primary role to another replica. That’s the easy case. Now I want to show what happens when the primary pod just disappears unexpectedly, like during a node failure or a container crash. No graceful shutdown, no demotion, just gone.

I ran two test scenarios, each cycling the primary role across all three pods by force-deleting the current primary three times in a row. First, a 5GB TPC-C database idle. Then, that same 5GB database under sustained HammerDB TPC-C load. Six force-deletes total, six successful automatic failovers. I’ll walk through the error log from the promoted replica, the operator’s detection and recovery behavior, and the full timing data.

Read on to see how Anthony’s SQL Server Kubernetes operator handles when things go bump in the night.

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Planned Failover of Availability Groups on Kubernetes

Published 2026-04-20 by Kevin Feasel

Anthony Nocentino runs a test:

When building the sql-on-k8s-operator, I wanted to make sure it could handle both planned and unplanned failovers. The easy case is a planned failover, where you deliberately move the primary role to another replica. The harder case is an unplanned failover, where the primary pod just disappears. The operator needs to handle both.

I recently ran a full planned failover rotation on a three-replica SQL Server Availability Group managed by sql-on-k8s-operator, and I want to show you exactly what happens inside SQL Server and the operator during each hop. If you’ve been following my Introducing the SQL Server on Kubernetes Operator post, this is the logical next step: what does the error log actually look like during a planned failover, what does the operator do in response, and how long does the whole thing take?

I ran the same three-hop rotation twice: once with an idle 5GB database to establish a baseline, and once under a sustained TPC-C workload with HammerDB. In this post, I’ll walk through the SQL Server error log entries, the operator’s reconcile behavior, and the timing data for both runs. In the next blog post, I’ll show what happens during an unplanned failover. Let’s go.

Click through to see how it all works.

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SQL Server Kubernetes Operator

Published 2026-04-13 by Kevin Feasel

Anthony Nocentino shares a new project:

Are you considering replatforming your SQL Server workload due to recent vendor changes, but still need high availability and disaster recovery? You’re not alone. One of the challenges with running SQL Server on Kubernetes is that there’s no Kubernetes operator available. That means no automated lifecycle management, no automatic failover, and no standard way to bootstrap an Always On Availability Group on Kubernetes.

I’m excited to share it today as an open-source project: sql-on-k8s-operator. Let’s go.

Click through to see what it entails. All in all, that’s really cool.

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Dockerizing Shiny and RMarkdown Apps

Published 2026-03-04 by Kevin Feasel

Thomas Williams builds a container image:

Running R Markdown via Docker is a big help with deploying those analysis and reports for others to use.

While there are alternatives for deploying R Markdown — the most popular being Shiny Server — they add the hassle of matching R and package versions to the machine where the code was developed, may require IT help, and mean sharing disk, CPU, and memory with other apps on the same server. And there’s also licensing requirements & limitations for the free version of Shiny Server.

R Markdown on Docker avoids some of these issues; a single Docker container = a single app.

Click through for a simple RMarkdown file and Dockerfile.

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SQL Server Container Startup Scripts

Published 2026-01-26 by Kevin Feasel

Andrew Pruski notices a change:

Hmm, ok we have a script /opt/mssql/bin/launch_sqlservr.sh and then the sqlservr binary is called.

I swear this wasn’t always the case, have I seen that before? Started to doubt myself so spun up a pod running an older version of SQL (2019 CU5) and took a look: –

It looks like this was a somewhat recent change, but with it comes an interesting new capability that Andrew shows off.

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Running PostgreSQL on Kubernetes

Published 2026-01-21 by Kevin Feasel

Umair Shahid digs into the arguments for and against:

“Should PostgreSQL run on Kubernetes too?”

The worst answers are the confident ones:

  • “Yes, because everything else is on Kubernetes.”
  • “No, because databases are special.”

Both are lazy. The right answer depends on what you’re optimizing for: delivery velocity, platform consistency, latency predictability, operational risk, compliance constraints, and, most importantly, who is on-call when things go sideways.

Click through for a detailed analysis. It’s a similar story in SQL Server:

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MinIO Alternatives

Published 2026-01-15 by Kevin Feasel

Robin Moffatt looks for alternatives:

In late 2025 the company behind MinIO decided to abandon it to pursue other commercial interests. As well as upsetting a bunch of folk, it also put the cat amongst the pigeons of many software demos that relied on MinIO to emulate S3 storage locally, not to mention build pipelines that used it for validating S3 compatibility.

In this blog post I’m going to look at some alternatives to MinIO.

Read on for Robin’s analysis of a half-dozen alternatives.

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Running SQL Server on KubeVirt

Published 2025-12-04 by Kevin Feasel

Andrew Pruski builds a virtual machine:

With all the changes that have happened with VMware since the Broadcom acquisition I have been asked more and more about alternatives for running SQL Server.

One of the options that has repeatedly cropped up is KubeVirt

KubeVirt provides the ability to run virtual machines in Kubernetes…so essentially could provide an option to “lift and shift” VMs from VMware to a Kubernetes cluster.

Read on to learn a bit more about KubeVirt, including how to set up a Windows-based virtual machine with it. Andrew does document some performance woes, so that’d be a big concern to work out the why behind this.

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