Init container dùng khi nào?

Init container chạy xong trước app containers. Nó phù hợp chuẩn bị file/config, chờ dependency nội bộ, chạy migration nhẹ có kiểm soát hoặc setup permission cho volume.

Ví dụ:

initContainers:
  - name: wait-db
    image: busybox:1.36
    command: ["sh", "-c", "until nc -z db 5432; do sleep 2; done"]

Không nên dùng init container để che lỗi kiến trúc như app không retry được dependency.

App production vẫn nên tự retry/backoff hợp lý.

An init container runs to completion before app containers. It fits preparing files/config, waiting for internal dependencies, running controlled lightweight migrations or setting up volume permissions.

Example:

initContainers:
  - name: wait-db
    image: busybox:1.36
    command: ["sh", "-c", "until nc -z db 5432; do sleep 2; done"]

Do not use init containers to hide architecture issues such as an app that cannot retry dependencies.

Production apps should still have sensible retry/backoff.