Coding Challenge (Minesweeper)

@mines/nest

The @mines/nest package in server-nest defines a server using NestJS to act as an API server. The API server has a naive authentication layer in LocalStrategy. The /auth/login endpoint uses this strategy to provide a JWT.

The API server includes a GraphQL endpoint courtesy of the @nestjs/graphql package. The NestJS GraphQL docs provide more detail on using the decorators which power the @nestjs/graphql setup.

Environment Variables

The Makefile will pull parameters defined in AWS SSM under the /mines/dev path and place them into .env. The .env.sample file includes the names of environment variables expected in all packages. The environment variables specific to the @mines/nest package are listed below.

• API_JWT_SECRET is used by LocalStrategy and JwtModule (via JwtConfigService). It is the symmetric secret used to sign JWTs generated and verified by the API.
• API_PORT is where the API will be served.

Database

The @mines/nest server uses a database to store data about the games it is serving. The database schema is managed through a set of database migrations using flyway community edition. The migrations are kept in migrations/versions, the configuration stored in migrations/config/flyway.conf points at a local postgres database, an appropriate configuration can be started using docker-compose.yml via docker-compose up -d db. To run the migrations from the project root:

flyway -configFiles=migrations/config/flyway.conf migrate

The above requires the flyway command to be accessible on the $PATH.

Testing

Unit tests are written with Jest and are complemented with Stryker. Test execution is done with the test or test:* scripts defined in server-nest/package.json.

• yarn test or yarn workspace @mines/nest test to execute tests once
• yarn test:watch or yarn workspace @mines/nest test:watch to execute tests related to recently changed files
• yarn test:e2e or yarn workspace @mines/nest test:e2e to execute "end to end" tests
• yarn workspace @mines/nest exec stryker run will execute the unit tests under the supervision of stryker in order to find places where changing the code doesn't break the tests

@mines/ui

The @mines/ui package in ui defines the components for the web ui. Ui.Dockerfile defines the Docker container for serving the web ui. Ui.Dockerfile is defined in the repository root in order to take advantage of Yarn workspaces. To build the web ui container locally execute:

docker build --file=Ui.Dockerfile --tag=mines-ui:<version> .

To run the locally built Docker image:

docker run --name=mines-ui --detach --publish=4000:3000 mines-ui:<version>

Environment Variables

The Makefile will pull parameters defined in AWS SSM under the /mines/dev path and place them into .env. The .env.sample file includes the names of environment variables expected in all packages. The environment variables specific to the @mines/ui package are listed below.

• UI_BASE_API_URL is base URL including scheme (and port if needed) of the API server.

@mines/uirs

The @mines/uirs package in ui-rs defines a web UI with yew-rs and mogwai. This is an experiment in building UI with WebAssembly.

http://www.sheshbabu.com/posts/rust-wasm-yew-single-page-application/

The rust based UI is being built with make in order to have more direct control over how wasm-pack is invoked. This can increase the feedback loop while developing the rust user interface. An alternative would be to use the @wasm-tool/wasm-pack-plugin with webpack, though this works the plugin is shelling out to wasm-pack under the hood. By invoking wasm-pack directly as needed it is possible to avoid lots of CPU intensive rust compilation cycles.

# Build the packaged distribution
make ui-rs/dist/index.html
# Build only the wasm files
make wasm
# Start the development server
yarn workspace @mines/uirs start

Environment Variables

The Makefile will pull parameters defined in AWS SSM under the /mines/dev path and place them into .env. The .env.sample file includes the names of environment variables expected in all packages. The environment variables specific to the @mines/uirs package are listed below.

• UI_BASE_API_URL is base URL including scheme (and port if needed) of the API server.

Running in Development

The .watchman directory contains configuration files for compiling the WASM files when Rust or Cargo files change in the @mines/uirs project. To use these files watchman needs to be installed. From the project root directory:

# Watch files in the project
watchman watch .
# Start rebuilding on changes
watchman -j < .watchman/mines-uirs-crates.json
# To tail the watchman log (which will include results of builds)
tail -f $(watchman get-sockname | jq --raw-output '.sockname' | sed 's/sock$/log/' | tr -d '\n')

The watchman configuration, paired with yarn workspace @mines/uirs start, will approximate the functionality of the @wasm-tool/wasm-pack-plugin but using the build defined in the Makefile.

The .watchman/mines-uirs-query.json contains the watchman query command to list the files watchman is tracking.

docker-compose

The docker-compose.yml defines a db using Postgres 13 database. The database is used to store data about created games.