A container packages a process and its runtime dependencies using an image. Persistent data and secrets need deliberate handling outside an image's disposable writable layer.
Before you begin
Be comfortable with variables, conditions, loops and basic methods. Use a small local project with a recorded JDK version and keep the input data fictional.
Work through the idea
Write the expected behavior before implementing the exercise. Keep the first version small enough to trace manually, then change one input or requirement. Record both the successful path and an invalid or empty-input case so that the result demonstrates reasoning rather than a copied output.
- Distinguish image from container
- Map ports intentionally
- Use a volume for required persistent data
Practice task
Run a fictional web service locally with an explicit port mapping and a nonsecret configuration.
Check your result
Explain what survives container replacement and how logs are accessed.
A mistake to avoid
Do not bake passwords into an image or assume a container is a virtual machine.
Keep a review note
Save the inputs or scenario, your reasoning and the result you checked. Explain one assumption and one case that needs more work. Revise the exercise after feedback and distinguish what you demonstrated from what remains untested.
Official reference for further study
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