Charmcraft bi-Weekly Dev Summary - 2020w21,22

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Ops (the operator framework itself)

  • We released 0.6.0 of the operator framework! You can grab it via pip install ops. This is the first “official” release, and includes a few breaking
    changes from what was in master until very recently. From now on, breaking
    changes will be announced, and we’ll have a deprecation procedure to ease
    things in (or rather, out). These breaking changes are:

    • The Framework object’s observe method’s second argument can no longer
      be an instance, and must be a method on an instance. That is, where
      previously you could write

      self.framework.observe(self.on.install, self)
      

      as a shortcut, but we found that this pushes people down a path that actually
      makes their charms less maintainable. Especially when it comes to writing
      components, it is better to have clearly named functions and clearly defined
      targets.

      So from now on the only supported way is to explicitly specify the callback
      method,

      self.framework.observe(self.on.install, self._on_install)
      

      (note we also recommend event handlers to be clearly marked as non-public).

    • Relations’ role attribute is now an enum, and in particular peer
      relation’s role is now "peer" (it used to be "peers" which was just
      wrong).

  • This release includes full support for Juju 2.8’s dispatch mechanism,
    including both use cases of dispatch being a symlink to the charm code, and
    dispatch being a small shim that executes the charm. The latter is an
    incremental improvement over what we mentioned in the last dev summary, and
    is already being used by charmcraft.

  • Model objects now have a name property (populated from
    JUJU_MODEL_NAME). This was a feature requested by charmers.

  • Lots of incremental API documentation additions. The URL for documentation
    is still the temporary one, as there are still three more weeks to go before
    we can potentially move to the one we want.

  • Support for Juju 2.8’s relation-created event. This should’ve been included
    in the last summary but slipped through the cracks…

Charmcraft

We released charmcraft 0.1.0! You can grab it via pip install charmcraft
(soon also available as a snap). This is very much an initial release, and there
are a lot of things still to do and things we know we want to do differently,
but it works!

In particular, charmcraft build will create a fully functional charm from a
barebones structure, such that you don’t need to care about the dispatch or
hooks symlinks! Huzzah. We even wrote a nice tutorial (still in progress,
once reasonably “done” we’ll also put it on discourse) on how you can use it.

Chatting …

We’re settling in to a bi-weekly cadence for meetings. If you are working on
operator framework charms, and haven’t chatted with us yet, please reach out! No
changes in the list of charmers we’ve been talking with since the last dev
summary
, but some changes will happen in the next few weeks as rotations kick
in.

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