Init container
An init container is a Kubernetes Pod container that performs initialization work to completion before the Pod’s application containers start.
Kubernetes in Action, Second Edition
An init container is a Kubernetes pod container that runs during initialization before the pod's regular containers start.
- How it is used
- Prepares a pod or delays its application containers until startup tasks complete.
- How deep it goes
- Explains manifest placement, ordered startup, inspection commands, and failure behavior without detailing every possible initialization task.
- Examples
- Uses a connectivity check and a shared emptyDir volume carrying a MongoDB initialization script.
- What you can do after
- Build it from scratch in a Pod manifest, then diagnose its startup with kubectl status, events, and logs.
Read how Kubernetes in Action, Second Edition explains init container →
Road to Kubernetes
An init container is a Kubernetes container that runs to completion before the main containers in a Pod start.
- How it is used
- Prepares a mounted volume before a PostgreSQL container starts in a StatefulSet.
- How deep it goes
- Defines execution order and demonstrates a cleanup command, but does not develop broader initialization patterns.
- Examples
- Uses an Alpine container to remove lost+found from a PostgreSQL volume before startup.
- What you can do after
- Configure a StatefulSet that cleans a mounted volume before its PostgreSQL container runs.
Related concepts
- containerkind of · A software container is an isolated execution environment that packages an application and its dependencies while sharing the host operating system kernel.
- kubectl execused by · kubectl exec is a kubectl command that runs a specified command inside a container in a Kubernetes Pod.
- restart policyconfigured by · A restart policy is a configuration rule specifying whether and when a container or workload is automatically restarted after termination or failure.
- kubectl logsused by · A kubectl command that retrieves log output produced by containers in a Kubernetes pod.
- emptydir volumeuses · An emptyDir volume is a Kubernetes volume that starts empty, is available to containers in a Pod, and is deleted when the Pod leaves its node.
- native sidecarincludes · A native sidecar is a Kubernetes init container with restartPolicy set to Always that runs alongside application containers with sidecar lifecycle ordering.
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