Peer authentication failed for user "postgres"

[teamon]

TASK: [Ansibles.postgresql | PostgreSQL | Make sure the PostgreSQL databases are present] ***
failed: [server] => (item={'name': u'mydb', 'hstore': True}) => {"failed": true, "item": {"hstore": true, "name": "mydb"}}
msg: unable to connect to database: FATAL:  Peer authentication failed for user "postgres"

vars:

app_postgresql_database: mydb # this is my custom DRY var

postgresql_ext_install_contrib: yes
postgresql_ext_install_dev_headers: yes

postgresql_databases:
  - name: "{{ app_postgresql_database }}"
    hstore: yes # sane default

postgresql_users:
  - name: "{{ app_postgresql_database }}"
    pass: "{{ app_postgresql_password }}"

postgresql_user_privileges:
  - name: "{{ app_postgresql_database }}"
    db: "{{ app_postgresql_database }}"
    priv: "ALL"

This used to work with no issues but somehow now it doesn't. The server is clean ubuntu 13.10x64

[teamon]

Looks like sudo is missing here:

# databases.yml
- name: PostgreSQL | Make sure the PostgreSQL databases are present
  sudo: yes
  sudo_user: "{{postgresql_admin_user}}"

[teamon]

There is also issue with 'Make sure the PostgreSQL users are present' but in this case adding sudo does not help:

msg: unable to connect to database: fe_sendauth: no password supplied

[teamon]

Ok, I figured out that restarting postgresql solves the problem, but that clearly mean that #1 is unfortunately not a proper fix