Add admin user for to reflect helm chart (#189)

* update environment doc and allow for env variable on admin username
* enable admin user when user defined admin password

ENVIRONMENT.rst

@@ -10,7 +10,12 @@ Environment Configuration Settings
 - **PGROOT**: a directory where we put the pgdata (by default /home/postgres/pgroot). One may adjust it to point to the mount point of the persistent volume, such as EBS.
 - **WALE_TMPDIR**: directory to store WAL-E temporary files. PGROOT/../tmp by default, make sure it has a few GBs of free space.
 - **PGDATA**: location of PostgreSQL data directory, by default PGROOT/pgdata.
+- **PGUSER_STANDBY**: username for the replication user, 'standby' by default.
 - **PGPASSWORD_STANDBY**: a password for the replication user, 'standby' by default.
+- **PGUSER_ADMIN**: username for the default admin user, 'admin' by default.
+- **PGPASSWORD_ADMIN**: a password for the default admin user, 'cola' by default.
+- **USE_ADMIN**: whether to use the admin user or not.
+- **PGUSER_SUPERUSER**: username for the superuser, 'postgres' by default.
 - **PGPASSWORD_SUPERUSER**: a password for the superuser, 'zalando' by default
 - **PGPORT**: port PostgreSQL listens to for client connections, 5432 by default
 - **SCOPE**: cluster name, multiple Spilos belonging to the same cluster must have identical scope.

postgres-appliance/configure_spilo.py

@@ -148,6 +148,14 @@ def deep_update(a, b):
   pg_hba:
     - hostssl all all 0.0.0.0/0 md5
     - host    all all 0.0.0.0/0 md5
+  {{#USE_ADMIN}}
+  users:
+    {{PGUSER_ADMIN}}:
+      password: {{PGPASSWORD_ADMIN}}
+      options:
+        - createrole
+        - createdb
+  {{/USE_ADMIN}}
 scope: &scope '{{SCOPE}}'
 restapi:
   listen: 0.0.0.0:{{APIPORT}}
@@ -274,6 +282,9 @@ def get_placeholders(provider):
     placeholders.setdefault('PGDATA', os.path.join(placeholders['PGROOT'], 'pgdata'))
     placeholders.setdefault('PGUSER_STANDBY', 'standby')
     placeholders.setdefault('PGPASSWORD_STANDBY', 'standby')
+    placeholders.setdefault('USE_ADMIN', 'PGPASSWORD_ADMIN' in placeholders)
+    placeholders.setdefault('PGUSER_ADMIN', 'admin')
+    placeholders.setdefault('PGPASSWORD_ADMIN', 'cola')
     placeholders.setdefault('PGUSER_SUPERUSER', 'postgres')
     placeholders.setdefault('PGPASSWORD_SUPERUSER', 'zalando')
     placeholders.setdefault('PGPORT', '5432')