kapil.thangavelu at canonical.com
Wed Oct 5 00:07:09 UTC 2011
I wanted inform the charm developer community about some important (and
backwards compatible) changes to handling addresses in units and charms that
came out from the local provider work.
0) Units now have public and private addresses associated to them.
1) Unit relation settings are now prepopulated with the unit's 'private-address'
Hooks no longer need to populate this information explicitly to communicate
to a related service. As an example a wordpress charm can get the address
for its associated mysql service by simply doing (assuming mysql just joined
in its db relation hooks. This obviates a common usage of 'relation-get' or
'relation-set' in hooks. These values are populated before the unit joins the
2) Hooks now have access to their unit's public and private address in a
provider independent fashion through a new hook cli api, called unit-get
A wordpress charm for example can obtain public address (for an apache vhost)
The unit-get command also returns values for 'private-address'.
The example formulas have been updated to use these new mechanisms.
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