Kotlin Spring Boot HATEOAS Database

Kick the tires on Spring Boot HATEOAS with a database. (Do not fret, this project uses an in-memory database that vanishes when you stop the program.)

Caveat emptor

This is a scratch, experimental repository. It might force push. It might be renamed without warning. It might vanish without warning.

How to use

First, ensure your clone builds cleanly:

$ ./mvnw clean verify

If satisfied, try running the program. In a first terminal, execute:

$ ./mvnw spring-boot:run
# Or with Docker
$ ./batect run

Once the program is ready (look for the "Started HateoasApplicationKt" message), in another terminal (if you don't use curlie or httpie, try curl or telnet though it will not be as nice to look at):

# Output: list of data endpoints
$ http localhost:8080/data
# Output: description of the AUTHORS database table
$ http localhost:8080/data/authors
# Output: first record in AUTHORS (Joanne Rowling is moby, is she not?)
$ http localhost:8080/data/authors/author-1
# Output: the first author in the database
$ http localhost:8080/rest/authors/author-1
# Output: the first author as GraphQL
$ http :8080/graphql query='{
  bookById(id: "book-1") {
    id
    title
    pageCount
    moby
    author {
      id
      firstName
      lastName
    }
  }
}'
# Output: all available endpoints
$ http localhost:8080/rest
# Output: list of admin endpoints
$ http localhost:8080/admin
# Output: everything should be in the UP state
$ http localhost:8080/admin/health

Before interrupting the first terminal process, try the data link again. Play around with the web page features. You cannot break anything (the database is in-memory). Sadly, there is no nice page for the admin links.

Before you change to another task, please interrupt the first terminal, and shutdown the demonstration.

Features

Pretty, auto-configured/auto-generated UI explorers

Open API (Swagger) UI
- Try http://localhost:8080/rest in a browser
HATEOAS UI
- Try http://localhost:8080/data in a browser
GraphQL UI, schema, and APIs
- Try http://localhost:8080/graphiql in a browser
- Try http://localhost:8080/graphql/schema
Generated OpenAPI specification
- After ./mvnw verify see target/openapi.json

In-memory persistence for demo

H2 in-memory database with dummy data preloaded ("Joanne Rowling")
- Try http://localhost:8080/rest/authors/author-1
- Try http://localhost:8080/data/authors/author-1
H2 console enabled
- Try http://localhost:8080/h2
- The JDBC connect string is jdbc:h2:mem:demo
- The user and password are "sa" and "password"

Additional Spring Boot features

Maximal actuator configuration
- Try http://localhost:8080/admin
Prometheus metrics
- Try http://localhost:8080/admin/prometheus
Auto-refresh of server on code changes for developers

Tracing/debugging from IDE

Run the program configured with JVM debugging. This configured in batect.yml for the standard port of 5005, and run as:

$ ./batect debug

Attach the remote debugging facility of your IDE to this port.

TODO

Sorting for REST
Paging and sorting for other endpoints
Test containers test (see binkley/modern-java-practices#278)

binkley/kotlin-spring-boot-hateoas-database