When registering a device, write a device ID

Summary:
Ref T5833. In some cases, we need to know if an Almanac device is the localhost or not, so we can either handle or forward the request.

To accomplish this, write a device ID when running `bin/almanac register`.

Using `--allow-key-reuse` and `--identify-as`, multiple devices are permitted to //authenticate// as one device but //identify// as different devices. In the Phacility cluster, this allows all the `repoXXX` machines to have one keypair (making key management much easier) but still work as separate devices. This is an advanced feature; normal installs with 1-3 hosts would just generate a key + device per host and identify/authenticate as the same device.

Test Plan: Ran commands with lots of flags like `PHACILITY_INSTANCE=local sudo -E ./bin/almanac register --device daemon.phacility.net --private-key ~/dev/core/conf/keys/daemon.key --force --allow-key-reuse --identify-as local001.phacility.net`. Got a good result from `AlmanacKeys::getDeviceID()` afterward.

Reviewers: btrahan

Reviewed By: btrahan

Subscribers: epriestley

Maniphest Tasks: T5833

Differential Revision: https://secure.phabricator.com/D11452

.gitignore

@@ -15,6 +15,7 @@
 /conf/local/VERSION
 /conf/keys/device.pub
 /conf/keys/device.key
+/conf/keys/device.id
 
 # Impact Font
 /resources/font/impact.ttf

src/applications/almanac/management/AlmanacManagementRegisterWorkflow.php

@@ -23,7 +23,15 @@ final class AlmanacManagementRegisterWorkflow
             'name' => 'allow-key-reuse',
             'help' => pht(
               'Register even if another host is already registered with this '.
-              'keypair.'),
+              'keypair. This is an advanced featuer which allows a pool of '.
+              'devices to share credentials.'),
+          ),
+          array(
+            'name' => 'identify-as',
+            'param' => 'name',
+            'help' => pht(
+              'Specify an alternate host identity. This is an advanced '.
+              'feature which allows a pool of devices to share credentials.'),
           ),
           array(
             'name' => 'force',
@@ -85,6 +93,7 @@ final class AlmanacManagementRegisterWorkflow
 
     $stored_public_path = AlmanacKeys::getKeyPath('device.pub');
     $stored_private_path = AlmanacKeys::getKeyPath('device.key');
+    $stored_device_path = AlmanacKeys::getKeyPath('device.id');
 
     if (!$args->getArg('force')) {
       if (Filesystem::pathExists($stored_public_path)) {
@@ -171,6 +180,24 @@ final class AlmanacManagementRegisterWorkflow
     Filesystem::writeFile($tmp_private, $raw_private_key);
     execx('mv -f %s %s', $tmp_private, $stored_private_path);
 
+    $raw_device = $device_name;
+    $identify_as = $args->getArg('identify-as');
+    if (strlen($identify_as)) {
+      $raw_device = $identify_as;
+    }
+
+    $console->writeOut(
+      "%s\n",
+      pht('Installing device ID...', $raw_device));
+
+    // The permissions on this file are more open because the webserver also
+    // needs to read it.
+    $tmp_device = new TempFile();
+    Filesystem::changePermissions($tmp_device, 0644);
+    execx('chown %s %s', $phd_user, $tmp_device);
+    Filesystem::writeFile($tmp_device, $raw_device);
+    execx('mv -f %s %s', $tmp_device, $stored_device_path);
+
     if (!$public_key->getID()) {
       $console->writeOut(
         "%s\n",
@@ -184,7 +211,7 @@ final class AlmanacManagementRegisterWorkflow
       pht(
         'This host has been registered as "%s" and a trusted keypair '.
         'has been installed.',
-        $device_name));
+        $raw_device));
   }
 
 }

src/applications/almanac/util/AlmanacKeys.php

@@ -9,4 +9,14 @@ final class AlmanacKeys extends Phobject {
     return $keys.ltrim($key_name, '/');
   }
 
+  public static function getDeviceID() {
+    $device_id_path = self::getKeyPath('device.id');
+
+    if (Filesystem::pathExists($device_id_path)) {
+      return trim(Filesystem::readFile($device_id_path));
+    }
+
+    return null;
+  }
+
 }