seedstack / coffig

Lightweight configuration library written in Java.

SeedStack config library "Coffig"

Coffig is a simple and powerful configuration library for the Java language. It is built upon the idea of mapping configuration trees to Java objects. The following configuration tree in YAML:

some:
  string: value1
  array: [1, 2, 3]
  object:
    attr1: value1
    attr2: [iris, jasmine, kiwi]

Can be retrieved as simply as:

Coffig coffig = Coffig.builder().withProviders(new JacksonProvider().addSource("url/to/file.yaml")).build();
    
String stringValue = coffig.get(String.class, "some.string");
int[] intArray = coffig.get(int[].class, "some.array");
MyPojo myPojo = coffig.get(MyPojo.class, "some.object");
String defaultValue = coffig.getOptional(String.class, "unknown.node").orElse("default");

Mapping

Coffig is able to map any Java class by introspecting its members but can handle special cases with dedicated mappers. Mappers for several types are built-in:

• Array,
• List,
• Set,
• Map,
• Enum,
• Optional,
• URI/URL,
• Properties,
• Class.

You can add you own mappers by implementing the ConfigurationMapper interface and registering it through the ServiceLoader mechanism.

Providers

Multiple providers can be used at once, each providing a separate configuration tree that will be merged into a global one. Several providers are built-in:

• Jackson (for YAML and JSON sources),
• Environment variables,
• System properties.

You can add you own mappers by implementing the ConfigurationProvider interface and registering it through the ServiceLoader mechanism.

Copyright and license

This source code is copyrighted by The SeedStack Authors and released under the terms of the Mozilla Public License 2.0.

coffig's Issues

Add an expression language system

A simple EL system would be very useful to declare aliases, use custom piped functions (for cypting, default values, etc.)

Here is a sample of what it could be. A more strict grammar will be defined later.

app.yml

security:
  username: user1
  password: ${"45f4sq654fgq6s54" | decrypt(env.keystore, "sha-256") | trim() | or("password") }

database:
  url: ${etcd.services.toto.url}

Create a Git config provider

This config provider would provide configuration from a set of files from a Git repository. This would support git refs like branches and tags.

Remove namedNodes() from TreeNode interface

The namedNodes() method is not useful on ArrayNode and ValueNode so investigate its removal from the TreeNode interface.