Design/implement a system to manage car pooling.
At Cabify we provide the service of taking people from point A to point B. So far we have done it without sharing cars with multiple groups of people. This is an opportunity to optimize the use of resources by introducing car pooling.
You have been assigned to build the car availability service that will be used to track the available seats in cars.
Cars have a different amount of seats available, they can accommodate groups of up to 4, 5 or 6 people.
People requests cars in groups of 1 to 6. People in the same group want to ride on the same car. You can take any group at any car that has enough empty seats for them. If it's not possible to accommodate them, they're willing to wait.
Once they get a car assigned, they will journey until the drop off, you cannot ask them to take another car (i.e. you cannot swap them to another car to make space for another group). In terms of fairness of trip order: groups are served in the order they arrive, but they ride opportunistically.
For example: a group of 6 is waiting for a car and there are 4 empty seats at a car for 6; if a group of 2 requests a car you may take them in the car for 6 but only if you have nowhere else to make them ride. This may mean that the group of 6 waits a long time, possibly until they become frustrated and leave.
This challenge has a partially automated scoring system. This means that before it is seen by the evaluators, it needs to pass a series of automated checks and scoring.
All checks need to pass in order for the challenge to be reviewed.
- The
acceptancetest step in the.gitlab-ci.ymlmust pass in master before you submit your solution. We will not accept any solutions that do not pass or omit this step. This is a public check that can be used to assert that other tests will run successfully on your solution. This step needs to run without modification - "further tests" will be used to prove that the solution works correctly. These are not visibile to you as a candidate and will be run once you submit the solution
There is a number of scoring systems being run on your solution after it is submitted. It is ok if these do not pass, but they add information for the reviewers.
To simplify the challenge and remove language restrictions, this service must provide a REST API which will be used to interact with it.
This API must comply with the following contract:
Indicate the service has started up correctly and is ready to accept requests.
Responses:
- 200 OK When the service is ready to receive requests.
Load the list of available cars in the service and remove all previous data (existing journeys and cars). This method may be called more than once during the life cycle of the service.
Body required The list of cars to load.
Content Type application/json
Sample:
[
{
"id": 1,
"seats": 4
},
{
"id": 2,
"seats": 6
}
]Responses:
- 200 OK When the list is registered correctly.
- 400 Bad Request When there is a failure in the request format, expected headers, or the payload can't be unmarshaled.
A group of people requests to perform a journey.
Body required The group of people that wants to perform the journey
Content Type application/json
Sample:
{
"id": 1,
"people": 4
}Responses:
- 200 OK or 202 Accepted When the group is registered correctly
- 400 Bad Request When there is a failure in the request format or the payload can't be unmarshaled.
A group of people requests to be dropped off. Whether they traveled or not.
Body required A form with the group ID, such that ID=X
Content Type application/x-www-form-urlencoded
Responses:
- 200 OK or 204 No Content When the group is unregistered correctly.
- 404 Not Found When the group is not to be found.
- 400 Bad Request When there is a failure in the request format or the payload can't be unmarshaled.
Given a group ID such that ID=X, return the car the group is traveling
with, or no car if they are still waiting to be served.
Body required A url encoded form with the group ID such that ID=X
Content Type application/x-www-form-urlencoded
Accept application/json
Responses:
- 200 OK With the car as the payload when the group is assigned to a car.
- 204 No Content When the group is waiting to be assigned to a car.
- 404 Not Found When the group is not to be found.
- 400 Bad Request When there is a failure in the request format or the payload can't be unmarshaled.
At cabify, we use Gitlab and Gitlab CI for our backend development work. In this repo you may find a .gitlab-ci.yml file which contains some tooling that would simplify the setup and testing of the deliverable. This testing can be enabled by simply uncommenting the final acceptance stage.
Additionally, you will find a basic Dockerfile which you could use a baseline, be sure to modify it as much as needed, but keep the exposed port as is to simplify the testing.
You are free to modify the repository as much as necessary to include or remove dependencies, but please document these decisions using MRs or in this very README adding sections to it, the same way you would be generating documentation for any other deliverable. We want to see how you operate in a quasi real work environment.
acceptance step of .gitlab-ci.yml, such as
docker-compose
First of all, make sure you have NodeJS installed by covering the official installation guide on your machine.
Once you have it, you can install and compile all dependencies by running on the project folder:
npm run install
Additionally you can run the unit tests
npm run test
Ensure you have MongoDB available on your machine. You can use either a local installation or a Docker distribution.
To start the application node server, run:
npm start
Now you can create request to localhost:9091 curl / postman....
To prepare you application for production, you can use Dockerfile for that. It will require you have Docker installed locally.
To build a Docker image, execute the following command:
docker build . -t car_pooling:latest
Once built, you are able to push it to a remote repository as:
docker push car_pooling:latest
It assumes you are authorized and logged in to a Docker registry.
On a different approach for a DropOff if for any reason when we do a drop off we delete the journey and release the seats on the car, I've implemented a retry system that after releasing a car from its passengers it will retry all journeys that don't have a car assigned and checks if after the release of the latest car some of them can be relocated on a car.
I reverted these changes (there are some comments on the code to enable again) because apparently of your tests when a dropOff is made the journey shouldn't be deleted (from my point of view, this is not very clear on your documentation), so, my approach didn't pass all of your tests.