You need to specify a sink and source like so:

var source = mysql({
  "uri": "mysql://user:pass@source.host.com:11111/database?ssl=custom",
  "tail": true,
  "cacert": "/path/to/source.crt",
})

var sink = mysql({
  "uri": "mysql://user:pass@sink.host.com:22222/database?ssl=custom",
  "cacert": "/path/to/sink.crt",
  "servername": "sink.host.com",
})

t.Source("source", source, "/.*/").Save("sink", sink, "/.*/")

• tailing is optional and only makes sense on the source
• For TLS you can use ssl=true which does unverified TLS or ssl=custom in which case you need to supply the cacert.
• You don't need to supply the servername, but if you do the certificate will be verified against it

• The source must allow the connecting user to query the binlog
• Per Postgresql you need to create the sink/destination table structure first

• Note that per the Postgresql adaptor this probably isn't very performant at copying huge databases as there is no bulk option yet.
• Has only been developed and tested using MySQL as the sink and source. Unsure how it will function when combined with other adaptors.