The Director General of Health Services has introduced the online Health Declaration Form to all Sri Lankans and foreigners travelling to Sri Lanka. The online Health Declaration Form should be completed prior to the arrival in Sri Lanka. The relevant link is as follows;
Whilst the vaccine certificate and PCR test results can also be submitted on arrival in hard copy, to avoid delays that may be encountered during verification of the documents, online submission could ensure swift entry for all arrivals. 
Embassy of Sri Lanka