Make runs reproducible when using --answer-file

Until now, using --answer-file could lead to small changes that
made runs non-reproducible. This patch aims at fixing that with
the following changes:

- Overwrite the answer file passed as a parameter with the
  processed answers. This is useful when enabling features that are
  not there by default, and end up with PW_PLACEHOLDER value in
  some variables.
- Make sure CONFIG_HEAT_AUTH_ENC_KEY is respected if entered in
  answer file.
- Make sure nova migration keys are not regenerated if already
  present.

Change-Id: I6837a2973aed9d29d6c44ac64b510f91b80f878a

packstack/installer/run_setup.py

@@ -639,6 +639,10 @@ def _main(options, configFile=None, logFile=None):
         path = _getanswerfilepath()
         if path:
             generateAnswerFile(path)
+    # If an answer file was provided, some options may have been overriden
+    # Overwrite answer file with updated options
+    else:
+        generateAnswerFile(options.answer_file)
 
     # Update masked_value_list with user input values
     _updateMaskedValueSet()

packstack/plugins/heat_650.py

@@ -61,7 +61,7 @@ def initConfig(controller):
          "MASK_INPUT": True,
          "LOOSE_VALIDATION": False,
          "CONF_NAME": "CONFIG_HEAT_AUTH_ENC_KEY",
-         "USE_DEFAULT": True,
+         "USE_DEFAULT": False,
          "NEED_CONFIRM": True,
          "CONDITION": False},
 

packstack/plugins/nova_300.py

@@ -452,10 +452,11 @@ def dummy_interface(host):
 
 def create_ssh_keys(config, messages):
     migration_key = os.path.join(basedefs.VAR_DIR, 'nova_migration_key')
-    # Generate key
-    local = utils.ScriptRunner()
-    local.append('ssh-keygen -t rsa -b 2048 -f "%s" -N ""' % migration_key)
-    local.execute()
+    # Generate key if it does not exist
+    if not os.path.exists(migration_key):
+        local = utils.ScriptRunner()
+        local.append('ssh-keygen -t rsa -b 2048 -f "%s" -N ""' % migration_key)
+        local.execute()
 
     with open(migration_key) as fp:
         secret = fp.read().strip()