You can create lombok.config files in any directory and put configuration directives in it. These apply to all source files in this directory and all child directories.
The configuration system is particularly useful for configurable aspects of lombok which tend to be the same across an entire project, such as the name of your log variable. The configuration system can also be used to tell lombok to flag any usage of some lombok feature you don't like as a warning or even an error.

Usually, a user of lombok puts a lombok.config file with their preferences in a workspace or project root directory, with the special config.stopBubbling = true key to tell lombok this is your root directory. You can then create lombok.config files in any subdirectories (generally representing projects or source packages) with different settings.

An up to date list of all configuration keys supported by your version of lombok can be generated by running:

1. java -jar lombok.jar config -g --verbose

A sample of available configuration options (see the feature pages of the lombok features for their related config keys, as well as java -jar lombok.jar config -g for the complete list):

lombok.accessors.chain

If set to true, generated setters will 'chain' by default (They will return this instead of having a void return type).

lombok.accessors.fluent

If set to true, generated setters and getters will simply be named the same as the field name, without a get or set prefix.

lombok.anyConstructor.addConstructorProperties

If true, lombok will generate a @java.beans.ConstructorProperties annotation when generating constructors. Note that you'll need to depend on module 'java.desktop' if you're using jigsaw.

lombok.log.fieldName

The name of the generated log field (default: log).

lombok.(featureName).flagUsage

Allows you to forcibly stop or discourage use of a lombok feature. Legal values for this key are warning or error. Some examples of values for (featureName) are: "experimental" (flags use of any of the experimental features), "builder", "sneakyThrows", or "extensionMethod".

Configuration files are hierarchical: Any configuration setting applies to all source files in that directory, and all source files in subdirectories, but configuration settings closer to the source file take precedence. For example, if you have in /Users/me/projects/lombok.config the following:

1. lombok.log.fieldName = foobar

1. lombok.log.fieldName = xyzzy

To restore a configuration key set by a parent config file back to the default, the clear option can be used. For example, if a parent configuration file has configured all use of val to emit a warning, you can turn off the warnings for a subdirectory by including in it a lombok.config file with:

1. clear lombok.val.flagUsage

Some configuration keys take lists. For lists, use += to add an entry. You can remove a single item from the list (useful to undo a parent configuration file's setting) with -=. For example:

1. lombok.accessors.prefix += m_

Comments can be included in lombok.config files; any line that starts with # is considered a comment.

These configuration keys have an effect on many or all lombok features, or on the configuration system itself.

To stop lombok from looking at parent directories for more configuration files, the special key:

1. config.stopBubbling = true

Lombok can add nullity annotations (usually called @NonNull and @Nullable) whenever it makes sense to do so; think of generated toString and withX methods (these never return null), or the parameter of a generated equals method, which is allowed to be null, and requires such an annotation if you've set up your IDE for strict null checks as well as 'parameters are non-null by default'. There are many such libraries; you must tell lombok which one to use. By default, no such annotations are added. Enable this feature with:

1. lombok.addNullAnnotations = <flavor>

Lombok can be configured to add @lombok.Generated annotations to all generated nodes where possible; useful for JaCoCo (which has built in support), or other style checkers and code coverage tools:

1. lombok.addLombokGeneratedAnnotation = true

Lombok can add the @SuppressFBWarnings annotation which is useful if you want to run FindBugs on your class files. To enable this feature, make sure findbugs is on the classpath when you compile, and add the following config key:

1. lombok.extern.findbugs.addSuppressFBWarnings = true

These config keys can make lombok affect source files even if they have 0 lombok annotations in them.

1. lombok.fieldDefaults.defaultPrivate = true
2. lombok.fieldDefaults.defaultFinal = true

At the top of a configuration file it is possible to import other configuration files. Imported files don't have to be called lombok.config and can have any file extension (or even none).

1. import ../configuration/model.config

For shared projects, it makes sense to always use relative paths. For individuals, it is also possible to use absolute paths.

1. # Linux
2. import /etc/lombok/model.config
3. # Windows
4. import d:/lombok/model.config

Configuration files can import multiple configuration files as long as they are specified before any configuration key. The system behaves as if the contents of the imported file are at the location of the import declaration.

The way the configuration system works is that duplicate entries are effectively ignored. It is a last-wins. Lombok will only process a configuration file once when resolving a specific value. This allows you to import the same files from different configuration files, and even create loops without any problems.

It is also possible to import files from .jar and .zip files.

1. # Use 'lombok.config' from the root of the archive.
2. import ../deps/lombok-config.jar
3. # Use a given file in the archive.
4. import ../deps/lombok-config.zip!base/model.config

When importing files, it is possible to use environment variables.

1. # Environment variables are names surrounded by angle brackets (<, >).
2. # They are replaced by System.getenv(name), if present.
3. import <JAVA_PROJECTS>/shared.config
4. # A tilde (~) at the start gets replaced by System.getProperty("user.home", "~").
5. import ~/my.config

This feature was added in lombok v1.20.0.