Previously, the engine would write to io.Writer's to display output.
When hosted in `pulumi` these writers were tied to os.Stdout and
os.Stderr, but other applications hosting the engine could send them
other places (e.g. a log to be sent to an another application later).
While much better than just using the ambient streams, this was still
not the best. It would be ideal if the engine could just emit strongly
typed events and whatever is hosting the engine could care about
displaying them.
As a first step down that road, we move to a model where operations on
the engine now take a `chan engine.Event` and during the course of the
operation, events are written to this channel. It is the
responsibility of the caller of the method to read from the channel
until it is closed (singifying that the operation is complete).
The events we do emit are still intermingle presentation with data,
which is unfortunate, but can be improved over time. Most of the
events today are just colorized in the client and printed to stdout or
stderr without much thought.
Internally we end up using flag to parse our command lines because of
our dependency on glog. When flag does not know about -C, if someone
passes -C before the sub command name (as is common for folks coming
from Git) the flag package terminates the program because -C was not
defined. So just teach flag this exists until we takle #301 and rid
ourselves of glog.
Previously, you could pass an explicit path to a Pulumi program when
running preview or update and the tool would use that program when
planning or deploying, but continue to write state in the cwd. While
being able to operate on a specific package without having to cd'd all
over over the place is nice, this specific implemntation was a little
scary because it made it easier to run two different programs with the
same local state (e.g config and checkpoints) which would lead to
surprising results.
Let's move to a model that some tools have where you can pass a
working directory and the tool chdir's to that directory before
running. This way any local state that is stored will be stored
relative to the package we are operating on instead of whatever the
current working directory is.
Fixes#398
This includes a few changes:
* The repo name -- and hence the Go modules -- changes from pulumi-fabric to pulumi.
* The Node.js SDK package changes from @pulumi/pulumi-fabric to just pulumi.
* The CLI is renamed from lumi to pulumi.
