Maps help simplify complicated configuration files. With maps you can insert or substitute values in a proxy configuration based on key-value pairs contained in map files. The map converters used to access the map files accept simple input such as request headers, path names, and fetches as keys to look up values to insert into the proxy configuration.
The map converters can search keys based on a variety of criteria, including string matches, substrings, IP addresses, regular expressions, and more. The value associated with the matched key is then inserted into the configuration where it can be further processed by ACLs and other expressions as needed.
A map file is a text file that often has the file extension .map, such as redirect_urls.map. HAProxy Enterprise reads map files during startup and loads their contents into memory. After startup, it does not read map files again. However, mappings can be updated at any time using the Runtime API.