Merge lp:~stub/charms/precise/postgresql/bug-1187508-allowed-hosts into lp:charms/postgresql

[Stuart Bishop]

This is a resubmission of https://code.launchpad.net/~davidpbritton/charms/precise/postgresql/trunk/+merge/171906, conflicts resolved and suggestions implemented.

This is to address Bug #1187508, where a client charm has no way of knowing if the credentials it has will actually work for it yet.

Simple change to set and export an "allowed-units" relation setting. This will show if you can connect to the database or not. Since the relations run asynchronously, there is no way to determine this otherwise. If your host is in the allowed_host setting, your client IP has been added to the hba conf file.

[Stuart Bishop (stub)]

The new relation setting can be tested with https://code.launchpad.net/~stub/charms/precise/postgresql-psql/trunk/+merge/174773

[David Britton (dpb)]

Stub: looks great! thanks for re-implementing.

[Marco Ceppi (marcoceppi)]

LGTM +1

review: Approve

=== modified file 'README.markdown'
--- README.markdown	2013-04-10 13:54:05 +0000
+++ README.markdown	2013-07-15 14:23:49 +0000
@@ -118,6 +118,8 @@
 - `user`: a regular user authorized to read the database
 - `password`: the password for `user`
 - `state`: 'standalone', 'master' or 'hot standby'.
+- `allowed-units`: space separated list of allowed clients (unit name).
+  You should check this to determine if you can connect to the database yet.
 
 ## During db-admin-relation-changed
 
@@ -128,3 +130,5 @@
 - `user`: a created super user
 - `password`: the password for `user`
 - `state`: 'standalone', 'master' or 'hot standby'
+- `allowed-units`: space separated list of allowed clients (unit name).
+  You should check this to determine if you can connect to the database yet.
 
=== modified file 'hooks/hooks.py'
--- hooks/hooks.py	2013-07-08 10:52:59 +0000
+++ hooks/hooks.py	2013-07-15 14:23:49 +0000
@@ -440,6 +440,7 @@
             # It's not an IP address.
             return addr
 
+    allowed_units = set()
     relation_data = []
     relids = hookenv.relation_ids('db') + hookenv.relation_ids('db-admin')
     for relid in relids:
@@ -477,6 +478,7 @@
                 raise RuntimeError(
                     'Unknown relation type {}'.format(repr(relid)))
 
+            allowed_units.add(unit)
             relation['private-address'] = munge_address(
                 relation['private-address'])
             relation_data.append(relation)
@@ -523,6 +525,13 @@
         owner="postgres", group="postgres", perms=0600)
     postgresql_reload()
 
+    # Loop through all db relations, making sure each knows what are the list
+    # of allowed hosts that were just added. lp:#1187508
+    # We sort the list to ensure stability, probably unnecessarily.
+    for relid in hookenv.relation_ids('db') + hookenv.relation_ids('db-admin'):
+        hookenv.relation_set(
+            relid, {"allowed-units": " ".join(unit_sorted(allowed_units))})
+
 
 def install_postgresql_crontab(postgresql_ident):
     '''Create the postgres user's crontab'''