Use rootpw for setting the root password instead of user

Ends up you cannot use the kickstart user command on root, since it
already exists, so we have to translate that into a rootpw command.

So [[customizations.user]] with name = "root" only support key, which
will set the ssh key, and password which will use rootpw to set the
password. plain text or encrypted are supported.

Related: rhbz#1626122

src/pylorax/api/compose.py

@@ -113,6 +113,32 @@ def repo_to_ks(r, url="url"):
     return cmd
 
 
+def write_ks_root(f, user):
+    """ Write kickstart root password and sshkey entry
+
+    :param f: kickstart file object
+    :type f: open file object
+    :param user: A blueprint user dictionary
+    :type user: dict
+
+    If the entry contains a ssh key, use sshkey to write it
+    If it contains password, use rootpw to set it
+
+    root cannot be used with the user command. So only key and password are supported
+    for root.
+    """
+    # ssh key uses the sshkey kickstart command
+    if "key" in user:
+        f.write('sshkey --user %s "%s"\n' % (user["name"], user["key"]))
+
+    if "password" in user:
+        if any(user["password"].startswith(prefix) for prefix in ["$2b$", "$6$", "$5$"]):
+            log.debug("Detected pre-crypted password")
+            f.write('rootpw --iscrypted "%s"\n' % user["password"])
+        else:
+            log.debug("Detected plaintext password")
+            f.write('rootpw --plaintext "%s"\n' % user["password"])
+
 def write_ks_user(f, user):
     """ Write kickstart user and sshkey entry
 
@@ -125,9 +151,6 @@ def write_ks_user(f, user):
     All of the user fields are optional, except name, write out a kickstart user entry
     with whatever options are relevant.
     """
-    if "name" not in user:
-        raise RuntimeError("user entry requires a name")
-
     # ssh key uses the sshkey kickstart command
     if "key" in user:
         f.write('sshkey --user %s "%s"\n' % (user["name"], user["key"]))
@@ -216,6 +239,14 @@ def add_customizations(f, recipe):
     if "user" in customizations:
         # only name is required, everything else is optional
         for user in customizations["user"]:
+            if "name" not in user:
+                raise RuntimeError("user entry requires a name")
+
+            # root is special, cannot use normal user command for it
+            if user["name"] == "root":
+                write_ks_root(f, user)
+                continue
+
             write_ks_user(f, user)
             user_groups.append(user["name"])