Allow macOS Install workflow tasks to link to externally hosted installer DMGs by URL

[Gerald Mcdonald]

When building workflows to install macOS or restore an ASR image, the source Install app/ASR image .DMGs are copied to and mounted from the main MDS.dmg.

This monolithic approach makes MDS.app updates and/or workflow edits more cumbersome as all the linked source macOS images are collected together with Imagr and other shared resources. The resulting MDS.dmg takes much longer to create and transfer to a separate webhost (if you’re not hosting from where you build it).

[timothy perfitt]

I implemented this in in build 21854 but not sure how useful it is going to be if your can’t mount via https, only http (I believe in Catalina HTTPS would work but only if it is trusted). Please test and see if it works for you.

[Kurt Fattic]

This works just fine. Thanks!