knowm/Konfig

Konfig

Konfig is a tool to deserialize JSON/YAML configuration files, while additionally validating and auto-generating documentation.

Description

Konfig is a fork of dropwizard-configuration. Konfig removes a few dependencies including Guava and Logback and does away with the need to add certain files in META_INF. Konfig allows you to serialize and deserialize configuration objects to either YAML or JSON from annotated Java classes. While deserializing, Konfig validates each property's given value if an appropriate annotation is included (@Min, @Max, etc.).

Konfig-dox is a Maven plugin that auto-generates documentation for your configuration classes based off the annotations and class and property JavaDocs. Given an array of package names to search, it will find all classes implementing Konfigurable and generate the documentation in JSON and HTML form.

Example.java

  private void goJSON() throws IOException, ConfigurationException {

    ConfigurableObject configurableObject =
        new Konfig<ConfigurableObject>()
            .buildConfigurationfromJSONFileAsResource(ConfigurableObject.class, "example.json");

    System.out.println(configurableObject.toString());
  }

example.json

{
    "name": "Coda Hale",
    "type": [
        "coder",
        "wizard"
    ],
    "properties": {
        "debug": true,
        "settings.enabled": false
    },
    "servers": [
        {
            "port": 8080
        },
        {
            "port": 8081
        },
        {
            "port": 8082
        }
    ],
    "my.logger": {
        "level": "info"
    }
}

ConfigurableObject.java

public class ConfigurableObject implements Konfigurable {

  @NotNull
  @Pattern(regexp = "[\\w]+[\\s]+[\\w]+([\\s][\\w]+)?")
  private String name;

  @JsonProperty private int age = 1;

  List<String> type;

  @JsonProperty private Map<String, String> properties = new LinkedHashMap<>();

  @JsonProperty private List<ExampleServer> servers = new ArrayList<>();

  private boolean admin;

  @JsonProperty("my.logger")
  private Map<String, String> logger = new LinkedHashMap<>();

  public String getName() {
    return name;
  }

  public List<String> getType() {
    return type;
  }

  public Map<String, String> getProperties() {
    return properties;
  }

  public List<ExampleServer> getServers() {
    return servers;
  }

  public boolean isAdmin() {
    return admin;
  }

  public void setAdmin(boolean admin) {
    this.admin = admin;
  }

  public Map<String, String> getLogger() {
    return logger;
  }

  @Override
  public String toString() {
    return "ConfigurableObject [name="
        + name
        + ", age="
        + age
        + ", type="
        + type
        + ", properties="
        + properties
        + ", servers="
        + servers
        + ", admin="
        + admin
        + ", logger="
        + logger
        + "]";
  }
}

Output

ConfigurableObject [name=Coda Hale, age=1, type=[coder, wizard], properties={debug=true, settings.enabled=false}, servers=[ExampleServer [port=8080], ExampleServer [port=8081], ExampleServer [port=8082]], admin=false, logger={level=info}]

Extra Options

You can override value with a Java Vm arg like this: -Dk.name="Tim Molter".
Annotations can be use to constrain fields: min, max, etc.
You can load config files as Strings, from resources and as a File.

Building

Konfig is built with Maven, which also handles dependency management.

general

cd path/to/project
mvn clean package
mvn javadoc:aggregate

knowm / Konfig