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This library loads properties files that can be used to configurean application including "testing" and "local development" anddynamic configuration (changes to configuration properties at runtime).

<dependency>  <groupId>io.avaje</groupId>  <artifactId>avaje-config</artifactId>  <version>${avaje.config.version}</version></dependency>

• Put application.yaml into src/main/resources for properties that have reasonable defaults
• Put application-test.yaml into src/test/resources for properties used when running tests
• Specify external properties via command line arguments. These effectively override application.yaml properties.

Getting property values

// get a String propertyStringvalue =Config.get("myapp.foo");// with a default valueStringvalue =Config.get("myapp.foo","withDefaultValue");// also int, long and boolean with and without default valuesintintVal =Config.getInt("bar");longlongVal =Config.getLong("bar");booleanbooleanVal =Config.getBool("bar");

Register callback on property change.

Config.onChange("myapp.foo",newValue -> {// do something ...});Config.onChangeInt("myapp.foo",newIntValue -> {// do something ...});Config.onChangeLong("myapp.foo",newLongValue -> {// do something ...});Config.onChangeBool("myapp.foo",newBooleanValue -> {// do something ...});

Config loads properties from expected locations as well as via command line arguments.Below is the how it looks for configuration properties.

• loads from main resources (if they exist)

  • application.yaml
  • application.properties

• loads files from the current working directory (if they exist)

  • application.yaml
  • application.properties

• loads via system propertyprops.file or environment variablePROPS_FILE (if defined)

• loads via system propertyavaje.profiles or environment variableAVAJE_PROFILES (if defined).

Setting theconfig.profiles or environment variableCONFIG_PROFILES will cause avaje config to load the property files in the formapplication-${profile}.properties (will also work for yml/yaml files).

For example, if you set theconfig.profiles todev,docker it will attempt to loadapplication-dev.properties andapplication-docker.properties.

• loads viaload.properties property.

We can define aload.properties property which has name of property file in resource folder, or path locations for other properties/yaml files to load.

load.properties is pretty versatile and can even be chained. For example, in your main application properties, you can haveload.properties=application-${profile:local}.properties to load based on another property, and in the loaded properties you can addload.properties there to load more properties, and so on.

Example application.properties:

common.property=valueload.properties=application-${profile:local}.properties,path/to/prop/application-extra2.properties

• loads test resources (if they exist, nb: Test resources are only visible when running tests)
  • application-test.properties
  • application-test.yaml

If no test resources were loaded then it additionally loads from "local dev" and command line:

• loads from "local dev".

We can specify anapp.name property and then put a properties/yaml file at:${user.home}/.localdev/{appName}.yamlWe do this to set/override properties when we want to run the application locally (aka main method)

• loads from command line arguments

Command line arguments starting with-P can specify properties/yaml files to load

When properties are loaded they are merged/overlayed.

If we setconfig.load.systemProperties to true then all the properties that have been loaded are then set into system properties.