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Scenario #316
Storage
Kubernetes v1.22, GKE
Mount Propagation Issues with Sidecar Containers
Sidecar containers didn’t see mounted volumes due to incorrect mountPropagation settings.
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What Happened
An app container wrote to a mounted path, but sidecar container couldn’t read the changes.
Diagnosis Steps
- 1Logs in sidecar showed empty directory.
- 2Checked volumeMounts: missing mountPropagation: Bidirectional.
Root Cause
Default mount propagation is None, blocking volume visibility between containers.
Fix/Workaround
• Added mountPropagation: Bidirectional to shared volumeMounts.Lessons Learned
Without correct propagation, shared volumes don’t work across containers.
How to Avoid
- 1Understand container mount namespaces.
- 2Always define propagation when using shared mounts.