I hit this bug as well, when trying out the minimal install for all-in-one inventory

===============
TASK: [mariadb | Cleaning up temp file on localhost] ************************** 
ok: [localhost -> 127.0.0.1]

TASK: [mariadb | Starting MariaDB data container] ***************************** 
changed: [localhost]

TASK: [mariadb | Starting MariaDB bootstrap container] ************************ 
changed: [localhost]

TASK: [mariadb | Sleeping for 15 seconds while the cluster starts] ************ 
ok: [localhost]

TASK: [mariadb | Starting MariaDB container] ********************************** 
changed: [localhost]

TASK: [mariadb | Creating haproxy mysql user] ********************************* 
failed: [localhost] => {"attempts": 10, "changed": false, "cmd": ["docker", "exec", "-t", "kolla_ansible", "/usr/bin/ansible", "localhost", "-m", "mysql_user", "-a", "login_host='10.161.16.77' login_port='3306' login_user='root' login_password='password' name='haproxy' password='' host='%'"], "delta": "0:00:00.718363", "end": "2015-12-08 05:15:05.505876", "failed": true, "rc": 2, "start": "2015-12-08 05:15:04.787513", "stdout_lines": ["localhost | FAILED! => {", "    \"changed\": false, ", "    \"failed\": true, ", "    \"msg\": \"unable to connect to database, check login_user and login_password are correct or ~/.my.cnf has the credentials. Exception message: (1045, \\\"Access denied for user 'root'@'sc-a01-050-222' (using password: YES)\\\")\"", "}"], "warnings": []}
stdout: localhost | FAILED! => {
    "changed": false, 
    "failed": true, 
    "msg": "unable to connect to database, check login_user and login_password are correct or ~/.my.cnf has the credentials. Exception message: (1045, \"Access denied for user 'root'@'sc-a01-050-222' (using password: YES)\")"
}
msg: Task failed as maximum retries was encountered

FATAL: all hosts have already failed -- aborting

PLAY RECAP ******************************************************************** 
           to retry, use: --limit @/root/site.retry

localhost                  : ok=51   changed=3    unreachable=0    failed=1

Command failed ansible-playbook -i /ssurana/kolla/tools/../ansible/inventory/all-in-one -e @/etc/kolla/globals.yml -e @/etc/kolla/passwords.yml /ssurana/kolla/tools/../ansible/site.yml
==========================

My setup is source based, ubuntu trusty install from the master branch.

Further debugging suggests that there is potentially some issue in the bootstrapping step. 
Seems like the "mysql_secure_installation" step is not getting through properly.

See logs from the container below:
===================================================================
root:~# docker logs -f mariadb
INFO:__main__:Kolla config strategy set to: COPY_ONCE
INFO:__main__:Loading config file at /var/lib/kolla/config_files/config.json
INFO:__main__:Validating config file
INFO:__main__:Copying service configuration files
INFO:__main__:Removing existing destination: /etc/mysql/my.cnf
INFO:__main__:Copying /var/lib/kolla/config_files/galera.cnf to /etc/mysql/my.cnf
INFO:__main__:Setting permissions for /etc/mysql/my.cnf
INFO:__main__:Writing out command to execute
Installing MariaDB/MySQL system tables in '/var/lib/mysql/' ...
151208  7:18:59 [Note] /usr/sbin/mysqld (mysqld 10.0.22-MariaDB-1~trusty-wsrep) starting as process 25 ...
151208  7:18:59 [Note] WSREP: Read nil XID from storage engines, skipping position init
151208  7:18:59 [Note] WSREP: wsrep_load(): loading provider library 'none'
151208  7:19:00 [Note] InnoDB: Using mutexes to ref count buffer pool pages
151208  7:19:00 [Note] InnoDB: The InnoDB memory heap is disabled
151208  7:19:00 [Note] InnoDB: Mutexes and rw_locks use GCC atomic builtins
151208  7:19:00 [Note] InnoDB: Memory barrier is not used
151208  7:19:00 [Note] InnoDB: Compressed tables use zlib 1.2.8
151208  7:19:00 [Note] InnoDB: Using Linux native AIO
151208  7:19:00 [Note] InnoDB: Using CPU crc32 instructions
151208  7:19:00 [Note] InnoDB: Initializing buffer pool, size = 128.0M
151208  7:19:00 [Note] InnoDB: Completed initialization of buffer pool
151208  7:19:01 [Note] InnoDB: The first specified data file ./ibdata1 did not exist: a new database to be created!
151208  7:19:01 [Note] InnoDB: Setting file ./ibdata1 size to 12 MB
151208  7:19:01 [Note] InnoDB: Database physically writes the file full: wait...
151208  7:19:02 [Note] InnoDB: Setting log file ./ib_logfile101 size to 48 MB
151208  7:19:03 [Note] InnoDB: Setting log file ./ib_logfile1 size to 48 MB
151208  7:19:11 [Note] InnoDB: Renaming log file ./ib_logfile101 to ./ib_logfile0
151208  7:19:11 [Warning] InnoDB: New log files created, LSN=45781
151208  7:19:11 [Note] InnoDB: Doublewrite buffer not found: creating new
151208  7:19:11 [Note] InnoDB: Doublewrite buffer created
151208  7:19:12 [Note] InnoDB: 128 rollback segment(s) are active.
151208  7:19:12 [Warning] InnoDB: Creating foreign key constraint system tables.
151208  7:19:12 [Note] InnoDB: Foreign key constraint system tables created
151208  7:19:12 [Note] InnoDB: Creating tablespace and datafile system tables.
151208  7:19:12 [Note] InnoDB: Tablespace and datafile system tables created.
151208  7:19:12 [Note] InnoDB: Waiting for purge to start
151208  7:19:12 [Note] InnoDB:  Percona XtraDB (http://www.percona.com) 5.6.26-74.0 started; log sequence number 0
151208  7:19:13 [Note] WSREP: Service disconnected.
151208  7:19:14 [Note] WSREP: Some threads may fail to exit.
151208  7:19:14 [Note] InnoDB: FTS optimize thread exiting.
151208  7:19:14 [Note] InnoDB: Starting shutdown...
151208  7:19:16 [Note] InnoDB: Shutdown completed; log sequence number 1616697
OK
Filling help tables...
151208  7:19:16 [Note] /usr/sbin/mysqld (mysqld 10.0.22-MariaDB-1~trusty-wsrep) starting as process 51 ...
151208  7:19:16 [Note] WSREP: Read nil XID from storage engines, skipping position init
151208  7:19:16 [Note] WSREP: wsrep_load(): loading provider library 'none'
151208  7:19:17 [Note] InnoDB: Using mutexes to ref count buffer pool pages
151208  7:19:17 [Note] InnoDB: The InnoDB memory heap is disabled
151208  7:19:17 [Note] InnoDB: Mutexes and rw_locks use GCC atomic builtins
151208  7:19:17 [Note] InnoDB: Memory barrier is not used
151208  7:19:17 [Note] InnoDB: Compressed tables use zlib 1.2.8
151208  7:19:17 [Note] InnoDB: Using Linux native AIO
151208  7:19:17 [Note] InnoDB: Using CPU crc32 instructions
151208  7:19:17 [Note] InnoDB: Initializing buffer pool, size = 128.0M
151208  7:19:17 [Note] InnoDB: Completed initialization of buffer pool
151208  7:19:17 [Note] InnoDB: Highest supported file format is Barracuda.
151208  7:19:17 [Note] InnoDB: 128 rollback segment(s) are active.
151208  7:19:17 [Note] InnoDB: Waiting for purge to start
151208  7:19:17 [Note] InnoDB:  Percona XtraDB (http://www.percona.com) 5.6.26-74.0 started; log sequence number 1616697
151208  7:19:17 [Note] WSREP: Service disconnected.
151208  7:19:18 [Note] WSREP: Some threads may fail to exit.
151208  7:19:18 [Note] InnoDB: FTS optimize thread exiting.
151208  7:19:18 [Note] InnoDB: Starting shutdown...
151208  7:19:20 [Note] InnoDB: Shutdown completed; log sequence number 1616707
OK

To start mysqld at boot time you have to copy
support-files/mysql.server to the right place for your system

PLEASE REMEMBER TO SET A PASSWORD FOR THE MariaDB root USER !
To do so, start the server, then issue the following commands:

'/usr/bin/mysqladmin' -u root password 'new-password'
'/usr/bin/mysqladmin' -u root -h sc-a01-050-222 password 'new-password'

Alternatively you can run:
'/usr/bin/mysql_secure_installation'

which will also give you the option of removing the test
databases and anonymous user created by default.  This is
strongly recommended for production servers.

See the MariaDB Knowledgebase at http://mariadb.com/kb or the
MySQL manual for more instructions.

You can start the MariaDB daemon with:
cd '/usr' ; /usr/bin/mysqld_safe --datadir='/var/lib/mysql/'

You can test the MariaDB daemon with mysql-test-run.pl
cd '/usr/mysql-test' ; perl mysql-test-run.pl

Please report any problems at http://mariadb.org/jira

The latest information about MariaDB is available at http://mariadb.org/.
You can find additional information about the MySQL part at:
http://dev.mysql.com
Support MariaDB development by buying support/new features from MariaDB
Corporation Ab. You can contact us about this at <email address hidden>.
Alternatively consider joining our community based development effort:
http://mariadb.com/kb/en/contributing-to-the-mariadb-project/

151208 07:19:21 mysqld_safe Logging to '/var/lib/mysql//sc-a01-050-222.err'.
151208 07:19:21 mysqld_safe Starting mysqld daemon with databases from /var/lib/mysql/
151208 07:19:21 mysqld_safe WSREP: Running position recovery with --log_error='/var/lib/mysql//wsrep_recovery.8xLm8C' --pid-file='/var/lib/mysql//sc-a01-050-222-recover.pid'
151208 07:19:24 mysqld_safe WSREP: Recovered position 00000000-0000-0000-0000-000000000000:-1
spawn mysql_secure_installation

NOTE: RUNNING ALL PARTS OF THIS SCRIPT IS RECOMMENDED FOR ALL MariaDB
      SERVERS IN PRODUCTION USE!  PLEASE READ EACH STEP CAREFULLY!

In order to log into MariaDB to secure it, we'll need the current
password for the root user.  If you've just installed MariaDB, and
you haven't set the root password yet, the password will be blank,
so you should just press enter here.

Enter current password for root (enter for none): 
ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/var/run/mysqld/mysqld.sock' (111 "Connection refused")
Enter current password for root (enter for none): 
ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/var/run/mysqld/mysqld.sock' (111 "Connection refused")
Enter current password for root (enter for none): 
ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: YES)
Enter current password for root (enter for none): 
ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: YES)
Enter current password for root (enter for none): 
ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: YES)
Enter current password for root (enter for none): 
ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: YES)
Enter current password for root (enter for none): 
ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: YES)

===================================================================

Thus in the bootstrap step the db is not getting configured as expected, thus causing the issue.

After doing some investigation on the issue it seems like the current version on "security_reset.expect" is causing the issue.

In my dev environment, I changed the syntax of the "expect" command 
From:
expect "Enter current password for root (enter for none):"
To:
expect {
  timeout { send_user "\nFailed to get password prompt\n"; exit 1 }
  eof { send_user "\nFailed to get password prompt\n"; exit 1 }
  "Enter current password for root (enter for none):"
}

based on the suggestions I found in the article https://www.pantz.org/software/expect/expect_examples_and_tips.html
and after that I was able to resolve the issue in my environment at least.
I will post a patch shortly with the improvements to the expect script