Locations ✖️ Ktor

Implementing a subset of Locations service spec using asynchronous Ktor framework.

Alternatives

Multiple implementations of this service exist in different frameworks, languages for comparison.

• locations-kt-http4k in Kotlin http4k; complete,
• locations-rs in Rust Actix; contains API spec and additional tools and data for testing, benchmarking.

Running

The service has runtime dependency on Elasticsearch instance with indices as explained in the elasticsearch directory of the locations-rs repository.

Locally

• Make sure you have GOOUT_ELASTIC_HOST and GOOUT_ELASTIC_PORT env vars set.
• ./gradlew build --continuous to build the app and keep watching for source changes
• ./gradlew run to launch the app. It will reload the classes when they're changed by the build process

In Docker

• ./gradlew shadowJar to build the fat jar
• docker build -t locations-ktor . to build the docker image
• docker run --rm -p 8080:8080 -e GOOUT_ELASTIC_HOST -e GOOUT_ELASTIC_PORT locations-ktor to run it

Notes from implementation by @goodhoko

• install ktor idea plugin
• project generation nice and straightforward with the plugin
• to have autoreaload you need to
  • configure the application.conf to scan for the class files
  • add a --continuous flag to the build task in idea run configurations
  • run both the run and build tasks simultaneously
• after DAY#1 this felt like a heaven compared to vertx
• support for lambdas and all the kotlin features makes the development very very pleasurable
• parsing enums from lowercase requires a manual workaround (https://github.com/ktorio/ktor/issues/399)
• project structure taken from the RealWorld example app
• Locations does not handle missing/optional query parameters well https://stackoverflow.com/questions/60632541/how-to-serve-http-400-when-missing-location-parameters