Package io.prometheus.metrics.config

Class PropertySource

java.lang.Object

io.prometheus.metrics.config.PropertySource

class PropertySource
extends Object

PropertySource encapsulates three separate property maps with different priorities and transformation rules.

Properties are checked in the following order:

1. External properties (highest priority) - exact key match
2. Environment variables (second priority) - with dot-to-underscore transformation
3. Regular properties (lowest priority) - from system properties, files, and classpath

Property lookups remove entries from the maps. This allows detecting unused properties at the end of configuration loading.

Field Summary

Fields

Modifier and Type	Field	Description
private final Map<Object,Object>	envVarProperties
private final Map<Object,Object>	externalProperties
private final Map<Object,Object>	regularProperties

Constructor Summary

Constructors

Constructor	Description
PropertySource(Map<Object,Object> regularProperties)	Creates a PropertySource with only regular properties (for testing).
PropertySource(Map<Object,Object> externalProperties, Map<Object,Object> envVarProperties, Map<Object,Object> regularProperties)	Creates a PropertySource with three separate property maps.

Method Summary

Modifier and Type	Method	Description
(package private) Set<String>	getAllKeys()	Returns all keys from all three property sources.
(package private) String	getProperty(String key)	Gets a property value by key, checking all three sources in priority order.
(package private) String	getProperty(String prefix, String propertyName)	Gets a property value by prefix and property name.
(package private) Set<String>	getRemainingKeys()	Returns all remaining keys from all three property sources.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Details

externalProperties

private final Map<Object,Object> externalProperties

envVarProperties

private final Map<Object,Object> envVarProperties

regularProperties

private final Map<Object,Object> regularProperties

Constructor Details

PropertySource

PropertySource(Map<Object,Object> externalProperties,
 Map<Object,Object> envVarProperties,
 Map<Object,Object> regularProperties)

Creates a PropertySource with three separate property maps.

Parameters:

externalProperties - properties passed explicitly (e.g., from application code)

envVarProperties - properties from environment variables (keys in env var format with underscores, lowercase)

regularProperties - properties from system properties, files, and classpath (keys normalized to snake_case)

PropertySource

PropertySource(Map<Object,Object> regularProperties)

Creates a PropertySource with only regular properties (for testing).

Creates empty maps for external and environment variable properties.

Parameters:

regularProperties - properties from system properties, files, and classpath (keys normalized to snake_case)

Method Details

getProperty

String getProperty(String key)

Gets a property value by key, checking all three sources in priority order.

For external and regular properties, performs exact key match. For environment variables, transforms dots to underscores before lookup (e.g., "io.prometheus.metrics.exemplars_enabled" becomes "io_prometheus_metrics_exemplars_enabled").

Removes the property from ALL source maps to prevent duplicate detection during validation.

Parameters:

key - the property key to look up

Returns:

the property value, or null if not found

getProperty

String getProperty(String prefix,
 String propertyName)

Gets a property value by prefix and property name.

This is a convenience method that concatenates the prefix and property name with a dot and calls getProperty(String).

Parameters:

prefix - the property prefix (e.g., "io.prometheus.metrics"), or empty string for no prefix

propertyName - the property name (e.g., "exemplars_enabled")

Returns:

the property value, or null if not found

getAllKeys

Set<String> getAllKeys()

Returns all keys from all three property sources.

Keys are returned in the format they are stored in each source: external and regular properties typically use dot-separated keys, while environment variables are exposed in their underscore form (e.g., "io_prometheus_metrics_exemplars_enabled").

This is used for pattern matching to find metric-specific configurations.

Returns:

a set of all property keys

getRemainingKeys

Set<String> getRemainingKeys()

Returns all remaining keys from all three property sources.

This is used for validation to detect unused properties that might indicate configuration errors.

Returns:

a set of all remaining property keys