HIV vs. Ebola Vaccine

Color me ignorant if that's the case, but how did an Ebola vaccine seemingly appear from thin air?

The way I see it we have been working for 30+ years on an HIV cure/vaccine and an Ebola crisis breaks out and they find a vaccine that quick.

I know that Ebola isn't new either but I also the intensity with which this vaccine was fast-tracked and the efforts put towards finding a solution. Versus what I see as a much slower and more relaxed desire to do the same for HIV.