nginx location matching rules explained

nginx_location.txt

    # READ (AND UNDERSTAND) THIS BEFORE MODIFYING THE location settings

#    location optional_modifier location_match {
#        ....
#    }
#
#    The location_match in the above defines what Nginx should check the request URI against. The existence or
#    nonexistence of the optional_modifier in the above example affects the way that the Nginx attempts to match the
#    location block. The modifiers below will cause the associated location block to be interpreted as follows:
#
#    * (none): If no modifiers are present, the location is interpreted as a prefix match. This means that the location
#              given will be matched against the beginning of the request URI to determine a match.
#    * =:      If an equal sign is used, this block will be considered a match if the request URI exactly matches the
#              location given.
#    * ~:      If a tilde modifier is present, this location will be interpreted as a case-sensitive regular expression
#              match.
#    * ~*:     If a tilde and asterisk modifier is used, the location block will be interpreted as a case-insensitive
#              regular expression match.
#    * ^~:     If a carat and tilde modifier is present, and if this block is selected as the best non-regular expression
#              match, regular expression matching will not take place.
#
#    Nginx begins by checking all prefix-based location matches (all location types not involving a regular expression).
#    It checks each location against the complete request URI.
#    * First, Nginx looks for an exact match. If a location block using the = modifier is found to match the request URI
#      exactly, this location block is immediately selected to serve the request.
#    * If no exact (with the = modifier) location block matches are found, Nginx then moves on to evaluating non-exact
#      prefixes. It discovers the longest matching prefix location for the given request URI, which it then evaluates as
#      follows:
#      * If the longest matching prefix location has the ^~ modifier, then Nginx will immediately end its search and
#        select this location to serve the request.
#      * If the longest matching prefix location does not use the ^~ modifier, the match is stored by Nginx for the
#        moment so that the focus of the search can be shifted.
#      * After the longest matching prefix location is determined and stored, Nginx moves on to evaluating the regular
#        expression locations (both case sensitive and insensitive). Nginx tries the regular expression locations
#        sequentially. The first regular expression location that matches the request URI is immediately selected to
#        serve the request.
#      * If no regular expression locations are found that match the request URI, the previously stored prefix location
#        is selected to serve the request.
#
#    It is important to understand that, by default, Nginx will serve regular expression matches in preference to prefix
#    matches. However, it evaluates prefix locations first, allowing for the administer to override this tendency by
#    specifying locations using the = and ^~ modifiers.
#
#    It is also important to note that, while prefix locations generally select based on the longest, most specific
#    match, regular expression evaluation is stopped when the first matching location is found. This means that
#    positioning within the configuration has vast implications for regular expression locations.