snap API challenge

This is a technical challenge for Canonical's snap team. The API can be looked at in a glace by visiting these docs.

Project Organization

cmd Directory

The cmd directory holds the entrypoint for the program. This folder's contents were generated by the goswagger code generator.

configure Directory

The configure directory contains code required to configure the service. This code runs before the service is considered active. It sets things up like a logger and the backend assets.

endpoints Directory

The endpoints directory is where the business logic of the service resides. These functions are triggered when an incoming request reaches out to an endpoint. The function is responsible for taking the data in the incoming request, talking to the backend code, and returning a normal or error response.

models Directory

The models directory contains the data structures that are specified in the swagger.yml. These data structures are how this server and its clients communicate. Its contents were generated by the goswagger code generator.

restapi Directory

The restapi directory contains the majority of generated code logic. These are things like, serving the API's visual interface, input validation, routing, etc. Its contents were generated by the goswagger code generator except for one special file. This special file is located at restapi/configure_snap_api_challenge.go. This file is hand edited to allow for configuration, setting endpoint handlers, and middleware.

Caddyfile File

The Caddyfile file is used to tell Caddy how to route traffic. Currently, the only instruction is to serve as a reverse proxy to the snapapi container, but it also serves as a TLS termination point in production.

docker-compose.yml File

The docker-compose.yml file is used to organize the containers for this service. It directs Docker images, persistent storage, port forwarding, and allows for administration via the docker-compose command.

Dockerfile File

The Dockerfile file is used to create a Docker image for the service. This Dockerfile is a two stage Dockerfile with the first stage building the code, and the second stage image only containing the binary and required configurations.

swagger.yml File

The swagger.yml file is used to describe the service. It specifies the endpoints, their parameters, and their responses. It is fed into the goswagger code generator to generate the server (and client) stubs for the service. The swagger.yml is a useful way to communicate how to interact with the service as it is a standardized and widely supported format.

Design

This service used the github.com/mvo5/qrest-skeleton/backend Go package as an external dependency. I did not change or add to any of the mock backend code.

This service's generated API documentation is hosted live at https://snapapi.micahparks.com/api/v0/docs. It can be used to understand the service better, generate requests, etc.

This service defaults resource limits to zero.

This service will not allow a quota-group to be added as a member to another quota-group if it is not already present in the quota manager.

This service was designed with bulk transactions in mind. All endpoints consume JSON that allows for the querying or manipulation of multiple quota-groups and/or members at once.

This service was designed as a containerized microservice using Docker.

This service is hosted live at snapapi.micahparks.com. It uses the image at micahparks/snapapi and snippets from this repo's docker-compose.yml and Caddyfile.

This service has a rate limiter middleware that allows for up to 1 request per second.

There repo has a couple TODOs which suggest improvements for the service. Most of these are listed below as well.

Running locally

Running the code on your local machine can take two forms. You may either use the go tool to compile and run, or use docker-compose.

Compiled with environment variables

HOST=0.0.0.0 PORT=30000 go run cmd/snap-api-challenge-server/main.go (This will use plaintext HTTP and use port 30000.)

Docker

docker-compose up (This will create a self-signed certificate and use ports 80 and 443.)

Testing

Testing is essential for any service. However, this service is a challenge and loosely time-boxed. I chose to not implement any formal tests for this service due to time.

However, there are two files, exampleCurl.local.sh and exampleCurl.sh that I quickly wrote to show that the service will perform what's expected of it in challenge.pdf's example. If you run the exampleCurl.sh script on an internet connected computer with curl installed, it will bring the live deployed service on the public internet to the state described in the example. If you run the service locally with the instructions under Compiled with environment variables, the exampleCurl.local.sh script will do the same to your local service.

Improvements

• Write Postman tests and Go tests utilizing httptest, gocheck, etc.
• Implement the usage portion in the backend.
• Add more logic to rate limiter middleware.
• More debug logging.
• Add a logging middleware.
• Use non-developer zap logger.