machan. apith tour ekak yanna inne May wala. Mata therunu widiyata e visa Sri Lankan passport ekata ba. Embassy eken ganna oni. Fee eka 12000 LKR

vietnam embassy ekata palayan.
on arrival ganna epa ban ethana check karala case ekak unoth return thamah
The tour guy arranges an on arrival visa. You require two photos (they do state a non standard size, but accepts photos of any size) and you pay the Visa fee in USD. Usually takes about 15 mins.
or details...
https://www.vietnam-immigration.net/visa-requirements/sri-lanka.html
tour ekakata set wenne natuwa wenama yanna baluwe