fix(deploy): set up 'colmena' wrapper for hardware-backed SSH keys

home/hosts/andromache/default.nix

@@ -45,6 +45,7 @@
   taskwarrior.enable = true;
   audio.enable = true;
   ssh.enable = true;
+  deploy.enable = true;
   music.enable = true;
   terminal.enable = true;
   devenv.enable = true;

home/hosts/astyanax/default.nix

@@ -50,6 +50,7 @@
     bash.addBinToPath = true;
   };
   ssh.enable = true;
+  deploy.enable = true;
   taskwarrior.enable = true;
   terminal.enable = true;
   reference-manager.enable = true;

home/modules/deploy/colmena-wrapper.bash

@@ -0,0 +1,68 @@
+# `colmena` wrapper script that opens a short-lived SSH master process for
+# `colmena` to use so it works with hardware-backed key touch+PIN. assumes
+# ControlPath ~/.ssh/socket-%r@%h:%p (see ./default.nix)
+
+selector=""
+want_on=0
+on_given=0
+deploy_cmd=0
+nodes=()
+on_nodes=()
+master_processes=()
+
+# build node list from `--on` value, a comma-separated string (e.g. "host-01,host-02")
+for arg in "$@"; do
+  if ((want_on)); then
+    selector="$arg"
+    want_on=0
+    continue
+  fi
+  case "$arg" in
+    --on=*)
+      selector="${arg#--on=}"
+      on_given=1
+      ;;
+    --on) want_on=1 on_given=1 ;;
+    apply | exec | upload-keys) deploy_cmd=1 ;;
+  esac
+done
+
+# shellcheck disable=SC2154
+if ((deploy_cmd)) && ! ((on_given)); then
+  on_nodes=("${!_colmena_node_tags[@]}")
+else
+  IFS=',' read -ra nodes <<< "$selector"
+  for node in "${nodes[@]}"; do
+    for node_tag in "${!_colmena_node_tags[@]}"; do
+      if [[ "$node" == @* ]]; then
+        for tag in ${_colmena_node_tags[$node_tag]}; do
+          # shellcheck disable=SC2053
+          [[ "$tag" == ${node#@} ]] && on_nodes+=("$node_tag")
+        done
+      else
+        # shellcheck disable=SC2053
+        [[ "$node_tag" == $node ]] && on_nodes+=("$node_tag")
+      fi
+    done
+  done
+fi
+
+for node in "${on_nodes[@]}"; do
+  # check if master process is running (see `man ssh`)
+  ssh -O check "$node" 2>/dev/null && continue
+
+  # place ssh client into "master" mode for connection sharing (see `man ssh`)
+  if ssh -fNM "$node"; then
+    master_processes+=("$node")
+  fi
+done
+
+rc=0
+@colmena@ "$@" || rc=$?
+
+# request master processes to exit (see `man ssh`)
+for process in "${master_processes[@]}"; do
+  ssh -O exit "$process" 2>/dev/null || true
+done
+
+exit "$rc"

home/modules/deploy/default.nix

@@ -0,0 +1,70 @@
+{
+  config,
+  lib,
+  pkgs,
+  inputs,
+  myUtils,
+  ...
+}:
+
+let
+  cfg = config.deploy;
+
+  hostDir = ../../../hosts;
+  hostNames = myUtils.dirNames hostDir;
+  hostsWithKeys = lib.filter (
+    hostname: builtins.pathExists (hostDir + "/${hostname}/ssh_host.pub")
+  ) hostNames;
+
+  colmena = inputs.colmena.packages.${pkgs.stdenv.hostPlatform.system}.colmena;
+
+  hostTags = hostname: (myUtils.hostMeta (hostDir + "/${hostname}")).tags;
+  remoteHostsWithKeys = lib.filter (
+    hostname: !(builtins.elem "local" (hostTags hostname))
+  ) hostsWithKeys;
+  nodeTagsDecl = ''
+    declare -A _colmena_node_tags=(
+    ${lib.concatMapStringsSep "\n" (
+      hostname: "  [${hostname}]=${lib.escapeShellArg (lib.concatStringsSep " " (hostTags hostname))}"
+    ) remoteHostsWithKeys}
+    )
+  '';
+
+  colmenaWrapped = pkgs.writeShellApplication {
+    name = "colmena";
+    runtimeInputs = [ pkgs.openssh ];
+    text =
+      nodeTagsDecl
+      + lib.replaceStrings [ "@colmena@" ] [ "${colmena}/bin/colmena" ] (
+        builtins.readFile ./colmena-wrapper.bash
+      );
+  };
+in
+{
+  options.deploy.enable = lib.mkEnableOption "deploy";
+
+  config = lib.mkIf cfg.enable {
+    assertions = [
+      {
+        assertion = config.ssh.enable;
+        message = "'home/modules/deploy' requires 'home/modules/ssh'";
+      }
+    ];
+
+    home.packages = [ colmenaWrapped ];
+    programs.ssh.settings = lib.genAttrs hostsWithKeys (
+      hostname:
+      let
+        meta = myUtils.hostMeta (hostDir + "/${hostname}");
+        isLocal = builtins.elem "local" meta.tags;
+      in
+      {
+        User = meta.host.username;
+      }
+      // lib.optionalAttrs (!isLocal) {
+        HostName = hostname;
+        ControlPath = "~/.ssh/socket-%r@%h:%p";
+      }
+    );
+  };
+}

home/modules/ssh/default.nix

@@ -2,17 +2,11 @@
   config,
   lib,
   pkgs,
-  myUtils,
   ...
 }:
 
 let
   cfg = config.ssh;
-  hostDir = ../../hosts;
-  hostNames = myUtils.dirNames hostDir;
-  hostsWithKeys = lib.filter (
-    hostname: builtins.pathExists (hostDir + "/${hostname}/ssh_host.pub")
-  ) hostNames;
 in
 {
   options.ssh.enable = lib.mkEnableOption "ssh";
@@ -24,30 +18,16 @@ in
       enable = true;
       enableDefaultConfig = false;
 
-      settings =
-        lib.genAttrs hostsWithKeys (
-          hostname:
-          let
-            meta = myUtils.hostMeta (hostDir + "/${hostname}");
-            isLocal = builtins.elem "local" meta.tags;
-          in
-          {
-            User = meta.host.username;
-          }
-          // lib.optionalAttrs (!isLocal) {
-            HostName = hostname;
-          }
-        )
-        // {
-          "*" = {
-            AddKeysToAgent = "yes";
-            ForwardAgent = false;
-            identityFile = [
-              "~/.ssh/id_ed25519_sk"
-              "~/.ssh/id_ed25519_sk_bak"
-            ];
-          };
+      settings = {
+        "*" = {
+          AddKeysToAgent = "yes";
+          ForwardAgent = false;
+          identityFile = [
+            "~/.ssh/id_ed25519_sk"
+            "~/.ssh/id_ed25519_sk_bak"
+          ];
         };
+      };
     };
   };
 }