Generally these jobs are for freshers and they require a set of thing from an individual. Those can be listed as follows:-
Basics in OS concepts / Linux/Unix Systems administration (Ubuntu, CentOS, RedHat, Solaris, etc).
Programming / scripting experience (Java, Perl, Ruby, C#, and/or PHP).
Basic knowledge in Networking (TCP/IP, DNS) /Database.
Exposure to Cloud computing.
Source:- Amazon Job Board