By don't creating the inituser file if it has already been done once.

disable FIPS explicitly, otherwise stunnel fails to start with the following output :

Threading:PTHREAD Sockets:POLL,IPv6 SSL:ENGINE,OCSP,FIPS
Reading configuration from file etc/stunnel.conf
FIPS_mode_set: F06D065: error:0F06D065:common libcrypto routines:FIPS_mode_set:fips mode not supported
Line 5: "[remote]": Failed to initialize SSL

so that responses without max-age will not be cached.