meiblorn / confij

ConfiJ is a Java configuration framework to facilitate loading and validating configurations from various sources in a type-safe manner.

ConfiJ - Configuration for Java

See the full documentation at https://keykey7.github.io/confij/

ConfiJ is a Java configuration framework to facilitate loading and validating configurations from various sources in a type-safe manner. This includes features such as:

• configuration definition as interfaces
• even as lists/maps/arrays/... of nested configurations
• support for various source formats: properties, YAML, HOCON, JSON, TOML
• load from various sources at once with different merge strategies
• load from: git, file, classpath, system properties, environment variables
• binding support to various immutable property types like URL, DateTime, Duration, enums, Period,...
• templating support (variable substitutions), even within paths
• plugin support for more formats and sources
• from simple non-null validation to powerful JSR303 bean validation
• live reloading hooks for change detection
• no external dependencies required by the core package

Example

Define your configuration in code:

interface HouseConfiguration {     // configuration definition as interfaces (or any)
    boolean hasRoof();             // bind to primitives
    LocalDate constructedAt();     // ...or to complex types, like temporal ones
    Room livingRoom();             // nested configurations
    Map<String, Room> rooms();     // ...even in Maps (usually immutable)
    Set<String> inhabitants();     // ...or Collections, Arrays
}
@NotNull                           // enforce well defined values (recursive)
interface Room {                   // nested definition
    @Default("1")                  // defaults and other customizations
    @Positive                      // optional full JSR303 bean validation
    int numberOfDoors();           // will become 1 if not defined otherwise
                                   //
    @Default("${numberOfDoors}")   // templating support: referencing other keys
    Optional<Integer> lockCount(); // explicit optionals
}

Load it as flexible as you need it (but always fail fast on unknown values):

HouseConfiguration johnsHouse = ConfijBuilder.of(HouseConfiguration.class)
    .loadFrom("classpath:house.properties")   // first read properties from classpath 
    .loadFrom("johnshouse.yaml")              // override with a YAML file on disk
    .loadOptionalFrom("*-test.${sys:ending}") // wildcards, variables, optional,...
    .loadFrom(EnvvarSource.withPrefix("APP")) // then read EnvVars like APP_hasRoof=true
    .build();                                 // build an immutable instance

# sample johnshouse.yaml
hasRoof: yes
constructedAt: 2000-12-24
livingRoom:
  numberOfDoors: 4
  lockCount: 1
rooms:
  bathRoom: {}
  kitchen:
    numberOfDoors: 2
inhabitants:
  - John
  - Alice

See the full documentation at https://keykey7.github.io/confij/

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