kexec installer package

.envrc

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+use flake

.gitignore

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+/.direnv
+/result
+/.pre-commit-config.yaml

flake.lock

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+{
+  "nodes": {
+    "flake-compat": {
+      "flake": false,
+      "locked": {
+        "lastModified": 1668681692,
+        "narHash": "sha256-Ht91NGdewz8IQLtWZ9LCeNXMSXHUss+9COoqu6JLmXU=",
+        "owner": "edolstra",
+        "repo": "flake-compat",
+        "rev": "009399224d5e398d03b22badca40a37ac85412a1",
+        "type": "github"
+      },
+      "original": {
+        "owner": "edolstra",
+        "repo": "flake-compat",
+        "type": "github"
+      }
+    },
+    "flake-utils": {
+      "locked": {
+        "lastModified": 1667395993,
+        "narHash": "sha256-nuEHfE/LcWyuSWnS8t12N1wc105Qtau+/OdUAjtQ0rA=",
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "rev": "5aed5285a952e0b949eb3ba02c12fa4fcfef535f",
+        "type": "github"
+      },
+      "original": {
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "type": "github"
+      }
+    },
+    "gitignore": {
+      "inputs": {
+        "nixpkgs": [
+          "pre-commit-hooks",
+          "nixpkgs"
+        ]
+      },
+      "locked": {
+        "lastModified": 1660459072,
+        "narHash": "sha256-8DFJjXG8zqoONA1vXtgeKXy68KdJL5UaXR8NtVMUbx8=",
+        "owner": "hercules-ci",
+        "repo": "gitignore.nix",
+        "rev": "a20de23b925fd8264fd7fad6454652e142fd7f73",
+        "type": "github"
+      },
+      "original": {
+        "owner": "hercules-ci",
+        "repo": "gitignore.nix",
+        "type": "github"
+      }
+    },
+    "nixpkgs": {
+      "locked": {
+        "lastModified": 1672617983,
+        "narHash": "sha256-68WDiCBs631mbDDk4UAKdGURKcsfW6hjb7wgudTAe5o=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "0fc9fca9c8d43edd79d33fea0dd8409d7c4580f4",
+        "type": "github"
+      },
+      "original": {
+        "owner": "NixOS",
+        "ref": "nixos-unstable",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "nixpkgs-stable": {
+      "locked": {
+        "lastModified": 1671271954,
+        "narHash": "sha256-cSvu+bnvN08sOlTBWbBrKaBHQZq8mvk8bgpt0ZJ2Snc=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "d513b448cc2a6da2c8803e3c197c9fc7e67b19e3",
+        "type": "github"
+      },
+      "original": {
+        "owner": "NixOS",
+        "ref": "nixos-22.05",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "pre-commit-hooks": {
+      "inputs": {
+        "flake-compat": "flake-compat",
+        "flake-utils": [
+          "flake-utils"
+        ],
+        "gitignore": "gitignore",
+        "nixpkgs": [
+          "nixpkgs"
+        ],
+        "nixpkgs-stable": "nixpkgs-stable"
+      },
+      "locked": {
+        "lastModified": 1672734157,
+        "narHash": "sha256-uwUBnv0bN1SO4QVIo8KUx/jxRYCy7cW8kzZa+Qsrw9k=",
+        "owner": "cachix",
+        "repo": "pre-commit-hooks.nix",
+        "rev": "d0ce0a861260493c6c21f16f59d25076f73cb931",
+        "type": "github"
+      },
+      "original": {
+        "owner": "cachix",
+        "repo": "pre-commit-hooks.nix",
+        "type": "github"
+      }
+    },
+    "root": {
+      "inputs": {
+        "flake-utils": "flake-utils",
+        "nixpkgs": "nixpkgs",
+        "pre-commit-hooks": "pre-commit-hooks"
+      }
+    }
+  },
+  "root": "root",
+  "version": 7
+}

flake.nix

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+{
+  description = "A very basic flake";
+
+  inputs = {
+    nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
+    flake-utils.url = "github:numtide/flake-utils";
+
+    pre-commit-hooks = {
+      url = "github:cachix/pre-commit-hooks.nix";
+      inputs.flake-utils.follows = "flake-utils";
+      inputs.nixpkgs.follows = "nixpkgs";
+    };
+  };
+
+  outputs = { self, nixpkgs, flake-utils, pre-commit-hooks }:
+    flake-utils.lib.eachSystem [ "x86_64-linux" ] (system:
+      let
+        pkgs = nixpkgs.legacyPackages.${system};
+        nixosConfig = nixpkgs.lib.nixosSystem {
+          inherit system;
+          modules = [
+            "${nixpkgs}/nixos/modules/installer/netboot/netboot-minimal.nix"
+            ({ pkgs, ... }: {
+              services.openssh = {
+                enable = true;
+                startWhenNeeded = true;
+              };
+
+              users.users.root.openssh.authorizedKeys.keyFiles = [
+                (pkgs.fetchurl {
+                  url = "https://github.com/eboskma.keys";
+                  sha256 = "uwK4FSLSHiwCJU9U7RBFHIoCmr7uUQLM0JM1u0bi4xo=";
+                })
+              ];
+
+              networking = {
+                useDHCP = true;
+              };
+
+              system.stateVersion = "23.05";
+            })
+          ];
+        };
+
+        kexecScript = pkgs.writeScript "kexec-installer" ''
+          #!/bin/sh
+          if ! kexec -v >/dev/null 2>&1; then
+            echo "kexec not found: please install kexec-tools" 2>&1
+            exit 1
+          fi
+          kexec --load ./bzImage \
+            --initrd=./initrd.zst \
+            --command-line "init=${nixosConfig.config.system.build.toplevel}/init ${toString nixosConfig.config.boot.kernelParams}"
+          if systemctl --version >/dev/null 2>&1; then
+            systemctl kexec
+          else
+            kexec -e
+          fi
+        '';
+      in
+      {
+        formatter = pkgs.nixpkgs-fmt;
+
+        checks = {
+          pre-commit-check = pre-commit-hooks.lib.${system}.run {
+            src = ./.;
+            hooks = {
+              nixpkgs-fmt.enable = true;
+              deadnix.enable = true;
+              statix.enable = true;
+              shellcheck = {
+                enable = true;
+                types_or = [ "executable" ];
+              };
+              shfmt.enable = true;
+            };
+          };
+
+        };
+
+        devShells.default = with pkgs; mkShell {
+          inherit (self.checks.${system}.pre-commit-check) shellHook;
+          name = "kexec-installer";
+        };
+
+        packages.kexec-installer = pkgs.linkFarm "netboot" [
+          { name = "initrd.zst"; path = "${nixosConfig.config.system.build.netbootRamdisk}/initrd.zst"; }
+          { name = "bzImage"; path = "${nixosConfig.config.system.build.kernel}/bzImage"; }
+          { name = "kexec-installer"; path = kexecScript; }
+        ];
+
+        packages.default = self.packages.${system}.kexec-installer;
+      });
+
+}