I saw the opening on the cern.ch/jobs website. I applied using their online application process. I was contacted around 2 weeks later for an online interview. Following this I was invited for a face to face interview about 3 weeks after that. The interview was over around a 4 hour period, there were two mini interviews inside of which involving a general knowledge interview and a technical interview and a full panel interview. There were 2 other candidates. Overall a very positive experience.