Generate development passwords.

I see little risk in using known passwords here, but it's such a bad
practice that I'd rather avoid it entirely.

(The worst case I can imagine is that a malicious process running on the
developer's workstation would be able to manipulate the configuration.)

dev.playbook.yml

@@ -4,8 +4,16 @@
   become: true
   vars:
     minimum_memory_mb: 4096
-    lockss_db_password: pass
-    lockss_ui_password: pass
+    lockss_db_password:
+      "{{ lookup('password',
+                 playbook_dir + '/.vagrant/provisioners/ansible/creds/' +
+                 'lockss_db-' + inventory_hostname +
+                 ' chars=ascii_letters,digits') }}"
+    lockss_ui_password:
+      "{{ lookup('password',
+                 playbook_dir + '/.vagrant/provisioners/ansible/creds/' +
+                 'lockss_ui-' + inventory_hostname +
+                 ' chars=ascii_letters,digits length=10') }}"
     lockss_hostname: "{{ hostname }}"
     lockss_ipaddr: "{{ external_ip }}"
     lockss_external_ipaddr: "{{ external_ip }}"
@@ -16,3 +24,6 @@
     - system-update
     - minimum_memory
     - lockss
+  tasks:
+    - debug:
+        msg: "LOCKSS UI password: {{ lockss_ui_password }}"