This exam closes the "Describe an application with Compose" module of the Docker course. The composition of a small application has been lost, and you must rebuild it on your own, with no hints, using what the lessons of the module taught you. It teaches you nothing new; it checks what you have learned. Allow about 45 minutes on a virtual machine running Docker Engine 29.9.2 and Compose 5.6.1.
What you will learn
- Say what the exam provides, what it expects and what it grades you on.
- Spot the lessons to review before you start.
- Read your result to decide whether to move on to the next module or to consolidate.
Prerequisites
The lessons of the "Use Docker" level and those of the module "Describe an application with Compose" must be finished, up to the last one, Persist the data of a recreated stack. The exam assumes that you know how to write a compose.yaml, read its effective configuration, connect services and keep their data.
Use the lab environment you used for the previous lessons. The images are provided: the exam asks you to build nothing.
What does the exam ask of you?
The statement describes an application of which only the images and a few values remain. You must write its composition and leave it in a state the lab can check: the application responds, it is reachable only where the statement asks, and its data survives when the stack is recreated.
Nobody tells you how the composition was written. The statement gives what the application must do, not the file that does it. This page does not describe the scenario, so that the exam stays a measurement. You will read it in the lab statement, and only there.
How is it graded?
The lab does not look at the commands you typed. It reads back the state of the system at the moment you hand in your work: what is running, what is reachable, what is published and what Compose has resolved. One of its checks also recreates the stack, then restores the original state. Two different compositions that end in the same state get the same grade.
Five checks of equal weight share the grade, and you must reach 75 points to pass. The grade is the number of checks passed divided by five, multiplied by a scale of 100 points minus the cost of the hints you asked for, rounded to the nearest integer (half to even in the case of an exact tie).
One requirement comes on top of the threshold: data lost when the stack is recreated fails the exam, even with everything else in place. A good total does not make up for lost data.
With no hint, four checks passed out of five give 80 points and are enough, provided the data survives the recreation. Each hint lowers the maximum you can reach, and the first one already requires a perfect score:
| Hints requested | Cumulative cost | Scale | 5 out of 5 | 4 out of 5 | Verdict |
|---|---|---|---|---|---|
| None | 0 | 100 | 100 | 80 | 4 out of 5 are enough |
| The first | 10 | 90 | 90 | 72 | 5 out of 5 required |
| The first two | 25 | 75 | 75 | 60 | 5 out of 5 required |
| The first three | 45 | 55 | 55 | 44 | Threshold not reachable |
| All four | 70 | 30 | 30 | 24 | Threshold not reachable |
Which rules apply?
This exam measures, it does not guide you. Three rules follow from that.
- The lab offers four hints, from the vaguest to the most explicit, and each one costs you points, from 10 for the first to 25 for the last. From the first hint, you must pass all five checks; beyond two, the threshold is no longer reachable. An exam passed without a hint is therefore passed in full.
- You may consult the lessons of the course and the official Docker documentation, as you would at work.
- The statement does not explain anything a second time, because the previous lessons have already taught what you need to know.
If you are stuck, compare what you wrote with what Compose understood: the effective configuration often shows where the gap lies.
Which lessons should you review before starting?
The statement does not say which actions it asks for, and this list does not try to point them out either. It gathers, in the order of the course, the lessons of the module that teach an action useful here. Start by rereading those where your last labs were difficult.
- Describe an application with Compose: a first stack
- Interpolation and environment files in Compose
- Organize the networks of a Compose stack
- Persist the data of a recreated stack
Take the exam
The lab prepares the machine, gives you the statement, then grades the state in which you leave it. Start it when you have about 45 minutes ahead of you, so that you can work in one go.
After the exam
If you pass the threshold without losing any data, you can describe and bring a Compose application back into service on your own, on the points the exam measures. You can move on to the next module. A result under the threshold does not mean that you failed to learn. It shows where the gap is.
The messages of the checks describe the symptom observed, not the action to take. It is up to you to link each failed check to a lesson in the list above, to reread it, then to redo the action yourself. Do not try to memorize an answer.
Key points
- The exam is a measurement. Nothing is explained a second time, hints cost points and the grade covers the final state of the system.
- The grading ignores the commands you typed. It looks at what is running, what is reachable, what is published and what Compose has resolved.
- You need 75 points to pass, and data lost when the stack is recreated fails the exam. A single hint requested already requires passing all five checks.
- The effective configuration is your first diagnostic tool: compare it with what you meant to write.
- To close a gap, reread the matching lesson, then redo the action.