revision now out of metadata.yaml

Gustavo Niemeyer gustavo.niemeyer at
Wed Oct 5 18:36:30 UTC 2011

Greetings folks,

I'm very happy to announce that the last conceptual change scheduled
and documented in the charm store specification for the 11.10 release
of juju is about to be landed, thanks to work by William Reade.

This change takes the "revision" field outside of the metadata.yaml
file, and into its own file named "revision" in the root of the charm
directory. This is being done in a backwards compatible way, and only
a warning will be emitted when a charm is found to use the old schema,
so you can do the migration gradually and without rushing.

The reason for this change is that the "revision" in charms was always
planned to be a machine-editable field that is automatically assigned
by the store in a sequential fashion. There was a conceptual conflict
in that regard with the rest of the fields within metadata.yaml, that
are manually-entered and should not be touched without the author's

This separation and the public/private addresses support that Kapil
announced yesterday were the last couple of significant changes to the
charm model that we really wanted to get in before 11.10, because it
puts us in a good position to evolve juju and the charms themselves
within the 11.10-to-12.04 timeframe in a compatible way.

Thanks a lot for your patience in the slightly agitated last couple of
weeks. With this in place you can then release your seat belts for a
slightly more comfortable trip with us.

Gustavo Niemeyer

-- I never filed a patent.

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