timello / springboot-demo-app

Small Spring Boot app dealing with database access, JSON APIs and logging

Springboot demo app

This is a small demo app created in Spring boot created to exercise automated deployments of non-trivial applications. It is a Java version of the flask-demo-app.

• Configuration based on environment variables
• Database-backed entries
• JSON API
• Stateless
• Support for X-Request-ID header for request tracking
• Logging with JSON to stdout

Model

The only model defined for the application is the model of an Entry.

An Entry is composed by the following fields:

• id: unique identifier for an entry. This field is generated automatically and cannot be modified.
• description: a description for the Entry.
• comment: a comment over the Entry.

Configuration

The following environment variables can be configured:

• APP_DATABASE_URL (mandatory): points to the backing database

• APP_DATABASE_USER (mandatory): holds the database user

• APP_DATABASE_PASSWORD (mandatory): holds the database password

• APP_DATABASE_SCHEMA (mandatory): specify what the persistence layer should do with the schema during the boot according to the options:

  • none: nothing is done
  • validate: schema is validated during initialization time
  • create: schema is reset during initialization time
  • update: schema is updated during initialization time

• APP_LOG_LEVEL (optional): allows configuring the application log level. If it is not specified, the default log level will be INFO.

• APP_FLYWAY_ENABLED (optional): whether Flyway-based migrations should be executed during boot. If left out, it will be enabled by default.

Note: If no database configuration is specified, the application will start on a single-shot execution mode using a memory-backed database that will be erased when it is stopped.

Database migration

Before running the application, the database must be setup. There are built-in migration scripts with Flyway to accomplish this. In order to run this, the following maven command must be executed:

$ export APP_DATABASE_USER=pxdtwhsbazfwdr
$ export APP_DATABASE_PASSWORD=fc06ba6b5f75e0c1ab303eb26a1332315ee53c0314b9ff34dcbbe7cc0b21005f
$ export APP_DATABASE_URL='jdbc:postgresql://ec2-54-247-189-64.eu-west-1.compute.amazonaws.com:5432/da8s86ph6ufuq7?ssl=true&sslfactory=org.postgresql.ssl.NonValidatingFactory'
$ mvn flyway:migrate

Deployment

All requirements for the application are specified in the pom.xml file.

The application is build with the command mvn package. The result will be an executable JAR under target/entries-X.X.X.jar, where X.X.X is the version number.

To execute the application, define all the required configuration variables and run the application with java -jar target/entries-X.X.X.jar, as below:

$ export APP_DATABASE_USER=pxdtwhsbazfwdr
$ export APP_DATABASE_PASSWORD=fc06ba6b5f75e0c1ab303eb26a1332315ee53c0314b9ff34dcbbe7cc0b21005f
$ export APP_DATABASE_URL='jdbc:postgresql://ec2-54-247-189-64.eu-west-1.compute.amazonaws.com:5432/da8s86ph6ufuq7?ssl=true&sslfactory=org.postgresql.ssl.NonValidatingFactory'
$ java -jar target/entries-X.X.X.jar

On the first execution, create the schema by also exporting APP_DATABASE_SCHEMA=create.

API

The following endpoints are offered:

• /api/v1/entries

  • parameters: none
  • methods: GET
  • description: list all entries in the database
  • accepts: all formats
  • returns: application/json

• /api/v1/entries

  • parameters: JSON object representing an Entry
  • methods: POST
  • description: create a new entry
  • accepts: application/json
  • returns: application/json

• /api/v1/entries/

  • parameters: JSON object representing an Entry
  • methods: POST
  • description: update an existing Entry
  • accepts: application/json
  • returns: application/json

• /api/v1/entries/

  • parameters: entry id
  • methods: DELETE
  • description: remove an entry from the database
  • accepts: all formats
  • returns: application/json

• /actuator/health

  • parameters: none
  • methods: GET
  • description: return "Status: UP" if the application is reachable
  • accepts: all formats
  • returns: application/json

• /actuator/prometheus

  • parameters: none
  • methods: GET
  • description: return metrics for Prometheus to scrape
  • accepts: all formats
  • returns: text/plain

License

This code is licensed under the MIT License.