Can't compile galera/2.x if ssl=0
g++ -o gcomm/test/check_types.o -c -Wno-long-long -Wno-deprecated -pedantic -ansi -Weffc++ -Wold-style-cast -g -O3 -DNDEBUG -pipe -Wall -Wextra -Werror -Wno-unused-parameter -m64 -D_XOPEN_SOURCE=600 -DGALERA_USE_GU_NETWORK -DHAVE_BYTESWAP_H -DHAVE_ENDIAN_H -DHAVE_BOOST_SHARED_PTR_HPP -DHAVE_BOOST_UNORDERED_MAP_HPP -DBOOST_DATE_TIME_POSIX_TIME_STD_CONFIG=1 -DGALERA_USE_BOOST_POOL_ALLOC=1 -DHAVE_ASIO_HPP -DHAVE_ASIO_HPP -Iasio -Igalerautils/src -Igcomm/src -Igcomm/src/gcomm -Igcache/src -Igcs/src -Iwsdb/src -Igalera/src gcomm/test/check_types.cpp
galera/tests/ist_check.o: In function `void boost::checked_delete<asio::ssl::detail::openssl_init<true>::do_init>(asio::ssl::detail::openssl_init<true>::do_init*)':
ist_check.cpp:(.text._ZN5boost14checked_deleteIN4asio3ssl6detail12openssl_initILb1EE7do_initEEEvPT_[void boost::checked_delete<asio::ssl::detail::openssl_init<true>::do_init>(asio::ssl::detail::openssl_init<true>::do_init*)]+0x17): undefined reference to `CRYPTO_set_id_callback'
ist_check.cpp:(.text._ZN5boost14checked_deleteIN4asio3ssl6detail12openssl_initILb1EE7do_initEEEvPT_[void boost::checked_delete<asio::ssl::detail::openssl_init<true>::do_init>(asio::ssl::detail::openssl_init<true>::do_init*)]+0x1e): undefined reference to `CRYPTO_set_locking_callback'
ist_check.cpp:(.text._ZN5boost14checked_deleteIN4asio3ssl6detail12openssl_initILb1EE7do_initEEEvPT_[void boost::checked_delete<asio::ssl::detail::openssl_init<true>::do_init>(asio::ssl::detail::openssl_init<true>::do_init*)]+0x23): undefined reference to `ERR_free_strings'
ist_check.cpp:(.text._ZN5boost14checked_deleteIN4asio3ssl6detail12openssl_initILb1EE7do_initEEEvPT_[void boost::checked_delete<asio::ssl::detail::openssl_init<true>::do_init>(asio::ssl::detail::openssl_init<true>::do_init*)]+0x2a): undefined reference to `ERR_remove_state'
ist_check.cpp:(.text._ZN5boost14checked_deleteIN4asio3ssl6detail12openssl_initILb1EE7do_initEEEvPT_[void boost::checked_delete<asio::ssl::detail::openssl_init<true>::do_init>(asio::ssl::detail::openssl_init<true>::do_init*)]+0x2f): undefined reference to `EVP_cleanup'
ist_check.cpp:(.text._ZN5boost14checked_deleteIN4asio3ssl6detail12openssl_initILb1EE7do_initEEEvPT_[void boost::checked_delete<asio::ssl::detail::openssl_init<true>::do_init>(asio::ssl::detail::openssl_init<true>::do_init*)]+0x34): undefined reference to `CRYPTO_cleanup_all_ex_data'
ist_check.cpp:(.text._ZN5boost14checked_deleteIN4asio3ssl6detail12openssl_initILb1EE7do_initEEEvPT_[void boost::checked_delete<asio::ssl::detail::openssl_init<true>::do_init>(asio::ssl::detail::openssl_init<true>::do_init*)]+0x3e): undefined reference to `CONF_modules_unload'
ist_check.cpp:(.text._ZN5boost14checked_deleteIN4asio3ssl6detail12openssl_initILb1EE7do_initEEEvPT_[void boost::checked_delete<asio::ssl::detail::openssl_init<true>::do_init>(asio::ssl::detail::openssl_init<true>::do_init*)]+0x43): undefined reference to `ENGINE_cleanup'
How important compilation with ssl=0 is? Enabling it would require additional logic - and with that additional complexity.