Currently we support OpenResty 1.15.8 ~ 1.19.3 Unlike the latter versions, OpenResty 1.15.8 has some limitations: * lack of support for OpenSSL 1.1.1 / TLS 1.3 * need some hack to simulate new features: https://github.com/apache/apisix/blob/b777146d00eb1682d78ab01be9064e79c151e0a4/apisix/cli/ngx_tpl.lua#L568
To make life easier, I think we should remove the support of OpenResty 1.15.8 gradually. First step, require OpenResty 1.17.8.2+ in rpm/deb package After a few months, we will remove OpenResty 1.15.8 support in the source code.
