Juju's dependencies, juju/utils and a road forward

[Tim Penhey]

Hi folks,

Juju has a problem with its dependencies. We have been trying to upgrade
a number of our dependencies recently have have been hitting road
blocks. Mostly because of changes to common libraries that are
incompatible with other libraries that we use.

I'm pretty sure that the root of all these problems is the juju/utils
package. It has become a dumping ground for any common functions that
packages may want to share. However these common functions are changed
arbitrarily with only thoughts around how they impact a subset of the
downstreams of juju/utils.

I think that the only sane way forward is to move all the functionality
we care about out of juju/utils into more cohesive, smaller, packages
that have meaningful names and you should be able to determine what they do.

Where the current clashes came from were a few places.
 1) we wanted to change our mgo dependency
 2) a new file path utility function was wanted
 3) the debugstatus package inside utils was updated in a backward
incompatible way

The root problem here is that the utils package tries to do too many
things. Any package called "utils" should be a warning, and we should
have listened to Dave Cheney when he brought this up originally.

I think the way forward is to break up the utils package. I'd like to
propose that we don't add anything new to the utils package, and only
deletions are allowed. We create new packages that contain the
functionality we require, and have them be much more controlled on their
own dependencies.

Thoughts?

Tim