# Antora Playbook Macros Extension


This allows you to use macros in your Antora playbook.

Configuration {#_configuration}

Any value in the playbook can use a macro with the `${key}` syntax. The
value will be replaced by the macro value as defined by one of the
following sources:

1.  Environment variable

2.  Uppercase environment variable

3.  Asciidoc attribute

4.  Default value

5.  Predefined macros

Asciidoc attributes comes from the `asciidoc.attributes` section of the
playbook. They can also be set in the antora command line using the
`--attribute` option.

Default values are defined in the `macros` section of extension
configuration. The provide a way to define default values for macros
that are not set in any other source.

The predefined macros are:

-   `branch`: The current branch name as per
    `git rev-parse --abbrev-ref HEAD`

-   `commit-id`: The current commit hash as per `git rev-parse HEAD`