This change fixes a couple bugs with assets:
* We weren't recursing into subdirectories in the new "path as
archive" feature, which meant we missed most of the files.
* We need to make paths relative to the root of the archive
directory itself, otherwise paths end up redundantly including
the asset's root folder path.
* We need to clean the file paths before adding them to the
archive asset map, otherwise they are inconsistent between the
path, tar, tgz, and zip cases.
* Ignore directories when traversing zips, since they aren't
included in the other formats.
* Tolerate io.EOF errors when reading the ZIP contents into blobs.
* Add test cases for the four different archive kinds.
This fixespulumi/pulumi-aws#50.
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 change brings the same typed serialization we use for RPC
to the serialization of deployments. This ensures that we get
repeatable diffs from one deployment to the next.
