Will Changing the Image Repository Force a Redeployment in Kubernetes?
Asked by
CuriousCoder42
I'm working with StatefulSets for Redis and RabbitMQ using the Bitnami helm charts and I have set the "imagePullPolicy" to "IfNotPresent". I'm planning to change the repository URL from Bitnami to Bitnami Archive; both have the exact same image content with matching MD5/hashes. I'm wondering if Kubernetes will recognize that there's no change and keep the current image cache and StatefulSet running, or if this change will trigger a new image pull and force a rollout of new application pods.
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Any change to the image tag, name, or repository location typically changes the pod template hash, which I would expect to trigger a redeployment or update.
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Honestly, I doubt Kubernetes has that kind of intelligence. From my experience, I think a rollout will occur, but the container runtime should reuse the cached image if available.
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Changing the spec.template will definitely cause a rollout since it changes the SHA of the replicaset. The only workaround I've found for StatefulSets is to set an onDelete strategy to avoid that behavior.
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From what I explored, changing the image URLs in CI from a local registry to GitLab's one doesn't always trigger a download of the images again if they have the same digest. However, be aware that it might still kick off a Kubernetes rollout even if no new downloads happen.
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DevOpsDude17: So it seems like there won't be a redownload, but is it confirmed that Kubernetes will trigger a rollout? That's a bit concerning.