What is the purpose of init containers in Kubernetes?

Init containers serve a distinctly important role in the lifecycle of a pod in Kubernetes. The primary purpose of init containers is to execute and complete tasks before the main application containers start. They are specialized for initialization processes that need to occur prior to the execution of the primary workload.

Init containers run sequentially, meaning each init container must complete successfully before the next one begins. If any of the init containers fail, the pod will not start, allowing developers to enforce necessary preconditions for the application, such as waiting for a service to be ready or performing setup tasks like database migrations.

By using init containers, you can ensure that your main application environments are correctly set up, leading to improved reliability and predictability of application behavior upon startup. This feature allows applications to start in a clean and ready state, mitigating common initialization issues.