Package org.apache.kafka.common.config

Class ConfigTransformer

java.lang.Object

org.apache.kafka.common.config.ConfigTransformer

public class ConfigTransformer
extends java.lang.Object

This class wraps a set of ConfigProvider instances and uses them to perform transformations.

The default variable pattern is of the form ${provider:[path:]key}, where the provider corresponds to a ConfigProvider instance, as passed to ConfigTransformer(Map). The pattern will extract a set of paths (which are optional) and keys and then pass them to ConfigProvider.get(String, Set) to obtain the values with which to replace the variables.

For example, if a Map consisting of an entry with a provider name "file" and provider instance FileConfigProvider is passed to the ConfigTransformer(Map), and a Properties file with contents

 fileKey=someValue
 

resides at the path "/tmp/properties.txt", then when a configuration Map which has an entry with a key "someKey" and a value "${file:/tmp/properties.txt:fileKey}" is passed to the transform(Map) method, then the transformed Map will have an entry with key "someKey" and a value "someValue".

This class only depends on ConfigProvider.get(String, Set) and does not depend on subscription support in a ConfigProvider, such as the ConfigProvider.subscribe(String, Set, ConfigChangeCallback) and ConfigProvider.unsubscribe(String, Set, ConfigChangeCallback) methods.

Field Summary

Fields

Modifier and Type	Field	Description
static java.util.regex.Pattern	DEFAULT_PATTERN

Constructor Summary

Constructors

Constructor	Description
ConfigTransformer(java.util.Map<java.lang.String,ConfigProvider> configProviders)	Creates a ConfigTransformer with the default pattern, of the form ${provider:[path:]key}.

Method Summary

Modifier and Type	Method	Description
ConfigTransformerResult	transform(java.util.Map<java.lang.String,java.lang.String> configs)	Transforms the given configuration data by using the ConfigProvider instances to look up values to replace the variables in the pattern.

Methods inherited from class java.lang.Object

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

Field Detail

DEFAULT_PATTERN

public static final java.util.regex.Pattern DEFAULT_PATTERN

Constructor Detail

ConfigTransformer

public ConfigTransformer(java.util.Map<java.lang.String,ConfigProvider> configProviders)

Creates a ConfigTransformer with the default pattern, of the form ${provider:[path:]key}.

Parameters:

configProviders - a Map of provider names and ConfigProvider instances.

Method Detail

transform

public ConfigTransformerResult transform(java.util.Map<java.lang.String,java.lang.String> configs)

Transforms the given configuration data by using the ConfigProvider instances to look up values to replace the variables in the pattern.

Parameters:

configs - the configuration values to be transformed

Returns:

an instance of ConfigTransformerResult