I set up an AWS server as a private bridge, but actually wanted to have a obfsproxy bridge.
Is it possible to change it later, or should I delete the old server and set up a new one?
The easiest way is to shut down the current instance and start a new one with the other image. Amazon charges by the hour, so you don't waste any money by doing so.
That being said, if you feel adventurous, it might be possible to turn your private bridge into a public one. I assume that the only difference is that your private bridge has an entry
PublishServerDescriptor 0 in its
torrc file that you could change to
PublishServerDescriptor bridge. But it could be that there are more differences, or that there will be more differences in the future. In general, people running cloud bridges want them to be zero configuration. After all, if they wanted to edit configuration files, they could as well start with a fresh image and install and configure
tor themselves. Of course, feel free to try it, and if you mess up, just delete the thing and start a new one. Enjoy!