add morph library

flake.nix

@@ -55,6 +55,7 @@
 
       lib = {
         getHosts = import lib/hosts.nix;
+        morphHosts = import lib/morph.nix;
         forAllSystems = f: builtins.listToAttrs (map
           (name: { inherit name; value = f name; })
           (builtins.attrNames nixpkgs.legacyPackages)

lib/morph.nix

@@ -0,0 +1,111 @@
+{ nixpkgs
+, nixosConfigurations
+, path
+, flake
+, extraMorphModules ? [ ]
+}:
+
+let
+
+  allHostsMeta = builtins.mapAttrs
+    (n: v: import (path + "/${n}"))
+    nixosConfigurations;
+
+in
+{
+  morph-entrypoint = system:
+    let
+      globalHealthChecks.cmd = [
+        {
+          cmd = [ "nixos-check-reboot" ];
+          description = "Check for pending reboot";
+        }
+        {
+          cmd = [ "systemctl is-system-running" ];
+          description = "Check services are running";
+        }
+      ];
+
+      getConfig = name: value: { ... }: {
+        imports = extraMorphModules ++ nixosConfigurations.${name}.extraArgs.modules;
+        config = nixpkgs.lib.mkMerge [
+          { inherit (allHostsMeta.${name}) deployment; }
+          { deployment.healthChecks = globalHealthChecks; }
+        ];
+      };
+
+    in
+    { network.pkgs = nixpkgs.legacyPackages.${system}; } //
+    builtins.mapAttrs getConfig nixosConfigurations;
+
+
+
+  packages = system:
+    let
+      pkgs = nixpkgs.legacyPackages.${system};
+      inherit (nixpkgs.lib) concatMapStrings;
+
+      sh = (scriptBody: pkgs.writeShellScriptBin "run" ''
+        set -e
+        die() { echo "$*" 1>&2 ; exit 1; }
+        ${scriptBody}
+      '');
+
+      sshKnownHostsTxt = pkgs.writeText "known_hosts" (concatMapStrings
+        (hostName:
+          let m = allHostsMeta.${hostName};
+          in concatMapStrings (key: "${m.deployment.targetHost} ${key}\n") m.sshPublicKeys
+        )
+        (builtins.attrNames nixosConfigurations)
+      );
+
+      sshConfig = pkgs.writeText "ssh_config" ''
+        StrictHostKeyChecking yes
+        GlobalKnownHostsFile ${sshKnownHostsTxt}
+      '';
+
+    in
+    rec {
+
+      morph-config = nixpkgs.legacyPackages.${system}.writeText "morph.nix" ''
+        let  flake = builtins.getFlake "${flake}";
+        in   flake.morph-entrypoint builtins.currentSystem
+      '';
+
+      morph = pkgs.runCommand "morph" { } ''
+        mkdir -p $out/bin
+        . ${pkgs.makeWrapper}/nix-support/setup-hook
+        makeWrapper ${pkgs.morph}/bin/morph $out/bin/morph \
+            --set SSH_USER root \
+            --set SSH_CONFIG_FILE ${sshConfig}
+      '';
+
+      deploy = sh ''
+        exec "${morph}/bin/morph" deploy ${morph-config} "$@"
+      '';
+
+      push = sh ''
+        exec "${morph}/bin/morph" push ${morph-config} "$@"
+      '';
+
+      ssh = sh ''
+        [ -n "$1" ] || die "Specify a host"
+        [ -d "${path}/$1" ] || die "Invalid host"
+        ip="$(nix eval --raw --file "${path}/$1" deployment.targetHost)"
+        shift
+        exec ssh -F"${sshConfig}" "$ip" "$@"
+      '';
+
+      check = sh ''
+        res="$( ${morph}/bin/morph build ${morph-config} )"
+        ${morph}/bin/morph check-health ${morph-config}
+        echo -e "\nUpdate checks:"
+        for hostname in $( ls "$res" ); do
+            echo "  $hostname"
+            diff \
+                <('${ssh}/bin/run' "$hostname" readlink /run/current-system) \
+                <(readlink "$res/$hostname") || true
+        done
+      '';
+    };
+}