This improves a few things about assets:
* Compute and store hashes as input properties, so that changes on
disk are recognized and trigger updates (pulumi/pulumi#153).
* Issue explicit and prompt diagnostics when an asset is missing or
of an unexpected kind, rather than failing late (pulumi/pulumi#156).
* Permit raw directories to be passed as archives, in addition to
archive formats like tar, zip, etc. (pulumi/pulumi#240).
* Permit not only assets as elements of an archive's member list, but
also other archives themselves (pulumi/pulumi#280).
This adds back Computed<T> as a short-hand for Promise<T | undefined>.
Subtly, all resource properties need to permit undefined flowing through
during planning Rather than forcing the long-hand version, which is easy
to forget, we'll keep the convention of preferring Computed<T>. It's
just a typedef and the runtime type is just a Promise.
As part of pulumi/pulumi-fabric#331, we've been exploring just using
undefined to indicate that a property value is absent during planning.
We also considered blocking the message loop to simplify the overall
programming model, so that all asynchrony is hidden.
It turns out ThereBeDragons 🐲 anytime you try to block the
message loop. So, we aren't quite sure about that bit.
But the part we are convicted about is that this Computed/Property
model is far too complex. Furthermore, it's very close to promises, and
yet frustratingly so far away. Indeed, the original thinking in
pulumi/pulumi-fabric#271 was simply to use promises, but we wanted to
encourage dataflow styles, rather than control flow. But we muddied up
our thinking by worrying about awaiting a promise that would never resolve.
It turns out we can achieve a middle ground: resolve planning promises to
undefined, so that they don't lead to hangs, but still use promises so
that asynchrony is explicit in the system. This also avoids blocking the
message loop. Who knows, this may actually be a fine final destination.
This fixes a few problems with dependent resolutions and hardens
even more promises-related error paths, so we swallow precisely zero
errors (or at least we hope so). This also digs through multi-level
chains of promises and computed properties as needed for nested mapValues.
This change renames String, File, and Remote to StringAsset, FileAsset,
and RemoteAsset, largely to avoid conflicting with the built-in JavaScript
String type, but also because it mirrors our Archive naming strategy.
The organization of packages underneath lib/ breaks the easy consumption
of submodules, a la
import {FileAsset} from "@pulumi/pulumi-fabric/asset";
We will go back to having everything hanging off the module root directory.
