534a01c2b0
curl does not retry if it is unable to connect to the metadata server. For some reason, when creating a new AMI with a recent nixpkgs, the metadata server would not be available when fetch-ec2-data ran. Switching to wget that can retry even on TCP connection errors solved this problem. I also made the fetch-ec2-data depend on ip-up.target, to get it to start a bit later.
*** NixOS *** NixOS is a Linux distribution based on the purely functional package management system Nix. More information can be found at http://nixos.org/nixos and in the manual in doc/manual.