Rewrite blog archive URLs to support a new URL format

To rewrite the URLs of a blog archive that follow the URL format /posts/<YYYY>-<MM>-<DD>-<TITLE> to the new format /posts/<YYYY>/<MM>/<DD>/<TITLE>, create the following rewrite URL rule:

http.request.uri.path ~ "^/posts/[0-9]+-[0-9]+-[0-9]+-.*"

regex_replace(http.request.uri.path, "^/posts/([0-9]+)-([0-9]+)-([0-9]+)-(.*)$", "/posts/${1}/${2}/${3}/${4}")

The function regex_replace() also allows you to extract parts of the URL using regular expressions’ capture groups. Create capture groups by putting part of the regular expression in parentheses. Then, reference a capture group using ${<NUMBER>} in the replacement string, where <NUMBER> is the number of the capture group.