{
  description = "devs & ops environment for nix'ing with triton";

  inputs.devshell.url = "github:numtide/devshell";
  inputs.flake-utils.url = "github:numtide/flake-utils";
  inputs.nixpkgs.url = "github:nixos/nixpkgs/release-21.11";
  inputs.nixpkgsUnstable.url = "github:nixos/nixpkgs/nixos-unstable";
  inputs.nixpkgs20-09.url = "github:nixos/nixpkgs/release-20.09";

  outputs = { self, flake-utils, devshell, nixpkgs, nixpkgsUnstable, nixpkgs20-09 }:
    flake-utils.lib.eachDefaultSystem (system: {

      # Internal utility package with shell function and env vars helper.
      # These get source'd in devshell.bash.extra when starting tritonshell
      packages.triton-utils = import ./pkgs/triton-utils.nix { inherit nixpkgs; inherit system; };

      devShell =
      let
        pkgs = import nixpkgs {
          inherit system;

          overlays = [ devshell.overlay ];
        };
        pkgsUnstable = import nixpkgsUnstable {
          inherit system;

          overlays = [ devshell.overlay ];
        };
        pkgs20-09 = import nixpkgs20-09 {
          inherit system;

          overlays = [ devshell.overlay ];
        };

        # HINT: add your extra pkgs here,
        # they'll get appended to devshell.packages in ./tritonshell.nix
        extraDevshellPkgs = [
          pkgsUnstable.consul
          pkgsUnstable.nomad
          pkgsUnstable.terraform
          pkgsUnstable.vault
        ];

      in
        import ./tritonshell.nix { inherit extraDevshellPkgs devshell pkgs pkgsUnstable pkgs20-09 self system; };
      });
}