lightbend/config

Features

• JVM Configuration Frameworks - Loads, merges, and resolves configuration files in HOCON, JSON, and Java properties formats for JVM applications.
• HOCON Parsers - Parses configuration files using the Human-Optimized Config Object Notation format with JSON and Java properties fallback.
• JVM Configuration Frameworks - Provides the core JVM configuration framework that loads and merges settings from multiple sources with priority-based overrides.
• Configuration Trees - Represents parsed configuration as an immutable tree that produces new instances on modification.
• Reference and Application Configs - Loads application configuration files from the classpath as the default application configuration.
• Classpath Reference Config Mergers - Automatically merges all reference configuration resources found on the classpath to provide default configuration values.
• Path-Based Value Retrieval - Fetches configuration values using dot-separated path expressions from the tree.
• Recursive Object Key Mergers - Recursively merges duplicate object-valued keys with later values overriding earlier ones.
• Path-Based Data Access - Navigates and extracts values from nested configuration structures using dot-notation paths.
• Automatic Type Converters - Automatically converts between string, number, boolean, and null types when accessing values.
• Configuration Value Type Converters - Returns configuration values in requested types with automatic coercion from string representations.
• Configuration Value Wrappers - Wraps a configuration value into a configuration object at a specified key or path for structured access.
• Configuration Value Mergers - Combines overlapping configuration values based on their data types with precedence rules.
• Environment Variable Config Overrides - Substitutes unresolved configuration references with environment variable values, optionally forcing overrides via a special prefix.
• Environment Variable Configuration - Resolves unresolved configuration substitutions by looking up matching environment variable values.
• Configuration File Loading - Loads configuration from files, URLs, classpath resources, and system properties, stacking them by priority.
• Configuration Merging - Combines settings from files, classpath resources, URLs, and system properties with fallback and override semantics.
• Multi-Source Configuration Loaders - Loads configuration from files, URLs, classpath resources, and system properties with priority-based overrides.
• Parsing Configuration Files - Parses HOCON, JSON, and Java properties files into a merged, immutable configuration tree.
• Multi-Format Config Parsers - Loads configuration from files, URLs, classpath resources, and system properties, merging them into a single immutable tree.
• Multi-Source Configuration Loaders - Loads configuration from files, classpath resources, URLs, and strings with include directives and recursive class loader inheritance.
• Object Merging - Combines configuration objects with precedence rules for layered settings.
• Java - Overrides any configuration value by setting Java system properties or environment variables with array index support.
• Environment Variable Substitution - Falls back to environment variables when a substitution is not found in the configuration tree.
• Configuration Variable Substitutions - Replaces placeholder references with values from the config tree, environment variables, or system properties.
• Configuration Tree Substitutions - Resolves ${...} placeholders by traversing the configuration tree and falling back to environment variables and system properties.
• Placeholder Resolutions - Resolves ${...} placeholders in configuration files using values from the same config, environment variables, or system properties.
• Dot-Notation Value Retrievers - Retrieves values from nested configuration objects using dot-separated key paths.
• Configuration Fallbacks - Provides fallback defaults for missing configuration fields through layered merging.
• Value Type Conversions - Transforms configuration values between types during retrieval with automatic coercion.
• Typed Configuration Value Retrievers - Retrieves configuration values as booleans, integers, durations, sizes, or strings with automatic type conversion.
• Path Reference Resolvers - Replaces path references in a config tree with their actual values, producing a fully resolved immutable configuration.
• Cross-Reference Substitutions - Uses substitution syntax to refer to another part of the configuration tree and resolve its value.
• Configuration Source Priority - Combines configurations from multiple sources with later sources overriding earlier ones in a defined priority order.
• Priority-Based Configuration Merging - Applies configuration layers based on a predefined priority order for merging.
• Dot-Notation Key Expanders - Expands dot-separated keys into nested objects during configuration parsing.
• Recursive Configuration Merging - Deeply merges multiple configuration objects into a final resolved settings tree.
• JavaBean Initializers - Populates Java object fields automatically from a matching configuration subtree.
• Configuration Array Appenders - Adds an element to an existing array using the += separator, creating the array if it does not exist.
• Self-Referential Array Appenders - Allows a configuration value to reference its own previous definition, enabling incremental value construction.
• Self-Referential Array Appends - Appends elements to arrays using the += operator by creating self-referential substitutions that expand at resolution time.
• Duration Parsers - Converts string input into time duration types for time-based configuration values.
• Period String Parsers - Parses date-based period strings from configuration into time period values.
• Include Directives - Imports another configuration file into the current file using an include statement, merging its keys into the current object.
• Reference Schema Validators - Checks that a configuration contains all keys present in a reference config, throwing an exception for mismatches.
• Include Directives - Loads configuration from URLs, files, or classpath resources using include directives, with optional failure on missing includes.
• Custom Parse Options - Parses configuration using user-specified parse and resolution options, such as class loader or allow-unresolved settings.
• Partial Resolvers - Resolves only a subset of substitutions in a configuration, leaving others unresolved for later processing.
• Memory Size String Parsers - Parses memory size strings from configuration into byte counts with unit support.
• Custom Source Substitutions - Sources variable substitutions from a user-provided configuration instead of the default self-referencing resolution.
• Custom Resolver Appenders - Appends custom resolvers to handle unresolved substitutions during configuration resolution.
• Path-Based Value Inserters - Inserts or overwrites a value at a specified path or key within an existing configuration.
• Dot-Key Tree Builders - Splits Java properties keys on dots to build a nested configuration object tree from flat property files.
• Configuration - Configuration library supporting HOCON, JSON, and properties.

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