An image captures dependencies that require ongoing maintenance. Rebuilding without changing pinned inputs does not necessarily incorporate fixes.
Before you start
You should understand the difference between an image, a running container and the host. Record where a file, process or network endpoint actually lives before diagnosing a problem. Commands illustrate local experiments; adapt image names and paths to a disposable development environment.
The practical goal is to reason through this situation: Update the selected base digest and rebuild application dependencies under controlled validation. Read the walkthrough first, then try the interview exercise before opening its answer. The important part is explaining the decision and its consequences, rather than remembering a definition alone.
Step-by-step walkthrough
Step 1: Identify pinned inputs
Base digest and dependencies determine what rebuilding actually changes.
Step 2: Update deliberately
Review changed inputs and validate application behavior under them.
Step 3: Retain tested recovery
Keep the previous digest and compatible deployment configuration.
Worked scenario
Update the selected base digest and rebuild application dependencies under controlled validation.
Rebuilding an unchanged pinned base produces no newer base fixes merely because time passed. Updating the selected digest introduces new content that needs testing. Image size is useful for transfer and surface considerations, but a tiny image can still contain obsolete or vulnerable components.
Common mistake
A small image is not automatically free from vulnerabilities or obsolete components.
Verify the behavior
Compare dependency content and test runtime behavior before promoting the revised image.
Interview exercise
Plan an image update.
Answer and reasoning
Review changes, test runtime behavior and retain a rollback digest; measure compatibility rather than trusting size alone.
Continue learning
Compare the scenario with the Docker interview questions and test your understanding with the Docker MCQs. For terminology and implementation details, consult the reference material.