[bundle] Fix local module refs for multi-cluster

[huguesalary]

This bug is caused by the relationship between the following components:

• The func (b *BundleBuilder) InitWorkspace(workspace string, runtimeValues map[string]string) error function in internal/engine/bundle_builder.go
• The BundleBuilder.files field
• The BundleBuilder.mapSourceToOrigin field
• The func (b *BundleBuilder) getInstanceUrl(v cue.Value) string function in internal/engine/bundle_builder.go

When called, the InitWorkspace goes through the list of files stored in b.files, parses them and writes the result in new files (let's call them "result files") located under the path indicated by workspace. In parallel, b.mapSourceToOrigin maps a "result file" path to the original file the result is based on.

At the end of the function, the original list b.files is replaced with the list of "result files".

The next invocation of InitWorkspace then uses b.files again, but this time it contains the previously computed "result files" paths.

So, for a given:

• b.files == ["/path/to/a/bundle.cue"]

calling InitWorkspace("/tmp/workspace1/"), will yield:

• b.files == ["/tmp/workspace1/bundle.cue"]
• b.mapSourceToOrigin["/tmp/workspace1/bundle.cue"]="/path/to/a/bundle.cue"

Then calling InitWorkspace("/tmp/workspace2/"), will yield:

• b.files == ["/tmp/workspace2/bundle.cue"]
• b.mapSourceToOrigin["/tmp/workspace2/bundle.cue"]="/tmp/workspace1/bundle.cue"

The getInstanceUrl relies on the mapSourceToOrigin being accurate to propely resolve relative file:// paths.

When getInstanceUrl() is called for the first bundle, it will propely resolve ./examples/redis/ to /path/to/a/examples/redis/.

When getInstanceUrl() is called for the second bundle, it will erroneously resolve ./examples/redis/ to /tmp/workspace1/examples/redis/.

This commit fixes this.

However it is worth noting that using a relative path for a file:// URI feels strange. Should it be allowed in the first place?

Fix #364

[huguesalary]

This fix doesn't work if -f - is used instead of an actual path to a file.

[stefanprodan]

However it is worth noting that using a relative path for a file:// URI feels strange. Should it be allowed in the first place?

This is how many tools work, for example Docker Compose, so I don't find it strange but actually useful.