Set up a low-cost VPN server easily with Docker

Amazon Lightsail now offers servers at $3.5 per month with 1 vCPU, 512MB of memory, and 1Tb of data transfer. Similar services are available at DigitalOcean. We can host personal VPN (virtual private network) servers cheaply. Docker containers enable quick configuration of these servers, even for people with little Linux experience. As someone who uses Google search and Google Scholar dozens times a day, I am especially concerned by the blockage of Google websites for scientists in some countries.