flake based on Nixpkgs Python

flake.nix

@@ -0,0 +1,31 @@
+{
+  description = "Description for the project";
+
+  inputs = {
+    flake-parts.url = "github:hercules-ci/flake-parts";
+    nixpkgs.url = "github:hercules-ci/nixpkgs/update-nixops_unstable";
+  };
+
+  outputs = inputs@{ flake-parts, ... }:
+    flake-parts.lib.mkFlake { inherit inputs; } {
+      imports = [
+      ];
+      debug = true;
+      systems = [ "x86_64-linux" "aarch64-linux" "aarch64-darwin" "x86_64-darwin" ];
+      perSystem = { config, self', inputs', pkgs, system, ... }: {
+        packages.nixops_with_aws =
+          (pkgs.nixops_unstable_minimal.addAvailablePlugins (self: super: {
+            nixops-aws = super.callPackage ./nix/nixops-aws.nix { };
+          })).withPlugins (plugins: [ plugins.nixops-aws ]);
+        packages.plugin = config.packages.nixops_with_aws.availablePlugins.nixops-aws;
+        # `plugin` would have been a valid choice, but a nixops is more useful. It builds fast.
+        packages.default = config.packages.nixops_with_aws;
+        devShells.default =
+          pkgs.mkShell {
+            inputsFrom = [ config.packages.plugin ];
+          };
+      };
+      flake = {
+      };
+    };
+}

nix/nixops-aws.nix

@@ -0,0 +1,62 @@
+{ lib
+, buildPythonPackage
+, fetchFromGitHub
+, unstableGitUpdater
+, poetry-core
+, boto
+, boto3
+, nixops
+, nixos-modules-contrib
+, typing-extensions
+}:
+
+buildPythonPackage {
+  pname = "nixops-aws";
+  version = "unstable-2023-08-09";
+  pyproject = true;
+
+  src =
+    with lib.fileset;
+    toSource {
+      root = ../.;
+      fileset = unions [
+        ../nixops_aws
+        ../pyproject.toml
+        ../setup.cfg
+        ../tests
+        ../tests.py
+      ];
+    };
+
+  postPatch = ''
+    substituteInPlace pyproject.toml \
+    --replace poetry.masonry.api poetry.core.masonry.api \
+    --replace "poetry>=" "poetry-core>="
+  '';
+
+  nativeBuildInputs = [
+    poetry-core
+  ];
+
+  buildInputs = [
+    nixops
+  ];
+
+  propagatedBuildInputs = [
+    boto
+    boto3
+    nixos-modules-contrib
+    typing-extensions
+  ];
+
+  pythonImportsCheck = [ "nixops_aws" ];
+
+  passthru.updateScript = unstableGitUpdater {};
+
+  meta = with lib; {
+    description = "AWS plugin for NixOps";
+    homepage = "https://github.com/NixOS/nixops-aws";
+    license = licenses.lgpl3Only;
+    maintainers = nixops.meta.maintainers;
+  };
+}

nixops_aws/nix/ec2.nix

@@ -1,12 +1,13 @@
 # Configuration specific to the EC2 backend.
 
-{ config, pkgs, lib, utils, ... }:
+{ config, pkgs, lib, options, utils, ... }:
 
 with utils;
 with lib;
 with import ./lib.nix lib;
 
 let
+  throwIf = lib.throwIf or (cond: msg: if cond then throw msg else x: x);
 
   types =
     if lib.types ? either then
@@ -165,7 +166,21 @@ let
 
   nixosVersion = builtins.substring 0 5 (config.system.nixos.version or config.system.nixosVersion);
 
-  amis = import <nixpkgs/nixos/modules/virtualisation/ec2-amis.nix>;
+  amisLegacy = import (pkgs.path + "/nixos/modules/virtualisation/ec2-amis.nix");
+
+  amisPath = pkgs.path + "/nixos/modules/virtualisation/amazon-ec2-amis.nix";
+  amis = import amisPath;
+
+  lookupAMI = { nixosVersion, region, system, virtType }:
+    assert builtins.trace "Looking up AMI for ${nixosVersion} in ${region} for ${system} with ${virtType}..." true;
+    if builtins.pathExists amisPath
+    then
+        (((amis.${nixosVersion} or amis.latest)
+        .${region} or (throw "No AMIs for region ${region}"))
+        .${system} or (throw "No AMIs for instance type ${system} in region ${region}"))
+        .${virtType} or (throw "No AMI for virtualisation type ${virtType} on instance type ${system} in region ${region}")
+    else
+      (amisLegacy.${nixosVersion} or amisLegacy.latest).${region}.${virtType};
 
 in
 
@@ -484,7 +499,7 @@ in
 
   config = mkIf (config.deployment.targetEnv == "ec2") {
 
-    nixpkgs.hostPlatform =
+    nixpkgs.${if options?nixpkgs.hostPlatform then "hostPlatform" else "system"} =
       let
         checked =
           throwIf (config.deployment.ec2.physicalProperties.platforms or [] == [])
@@ -507,7 +522,7 @@ in
           < ranking.${b.cpu} or unrankedRank;
 
         systemString =
-          lib.throwIf (plat.os or "linux" != "linux")
+          throwIf (plat.os or "linux" != "linux")
             "Instance does not seem to be intended for running Linux. Please set nixpkgs.hostPlatform manually."
           plat.cpu + "-linux";
       in
@@ -516,20 +531,18 @@ in
     deployment.ec2.ami = mkDefault (
       let
         # FIXME: select hvm-s3 AMIs if appropriate.
-        type =
+        virtType =
           if isEc2Hvm then
             if cfg.ebsBoot then "hvm-ebs" else "hvm-s3"
           else
             if cfg.ebsBoot then "pv-ebs" else "pv-s3";
-        amis' = amis."${nixosVersion}" or amis.latest;
       in
-        with builtins;
-        if hasAttr cfg.region amis' then
-          let r = amis'."${cfg.region}";
-        in if hasAttr type r then r."${type}" else
-          throw "I don't know an AMI for virtualisation type ${type} with instance type ${cfg.instanceType}"
-        else
-          throw "I don't know an AMI for region ‘${cfg.region}’ and platform type ‘${config.nixpkgs.hostPlatform.system}’"
+        lookupAMI { 
+          inherit virtType;
+          inherit nixosVersion;
+          inherit (cfg) region;
+          system = config.nixpkgs.hostPlatform.system or config.nixpkgs.system;
+        }
       );
 
     # Workaround: the evaluation of blockDeviceMapping requires fileSystems to be defined.

pyproject.toml

@@ -11,7 +11,7 @@ python = "^3.7"
 boto = "^2.49.0"
 boto3 = "^1.13.7"
 nixops = {git = "https://github.com/NixOS/nixops.git", rev = "master"}
-typing-extensions = "^3.7.4"
+typing-extensions = ">=3.7 <=5"
 nixos-modules-contrib = {git = "https://github.com/nix-community/nixos-modules-contrib.git", rev = "master"}
 
 [tool.poetry.dev-dependencies]