Downloading and Installing Libraries in the Package Manager

[radeusgd]

Summary

We need to implement the logic for downloading a specific library version.

Value

• Libraries can be downloaded from the repository.

Specification

• A helper that updates the available editions - download the list of editions and download any missing edition files.
  • A setting file that specifies sources for the editions, initially only our main repo, but custom repos could be added here.
  • In the future we may consider not downloading nightlies by default as only advanced users will use those, so this may be a setting - for now we will download all editions though, but a note should be left about this.
    • I just realised that there is no sense in providing filters - we can just have a separate repository for the nightly editions (just a separate directory on the same webserver will sufice) and so users will be able to select if they want to enable the nightly edition provider or not.
  • Implement a launcher command to update editions.
  • Finish the implementation of the editions/listAvailable endpoint to update editions if asked to.
• Implement a LibraryProvider that loads libraries from the cache and falls back to downloading if necessary.
• Parser for library manifest and metadata files.
• Download the manifest file for the library.
• Recursively install all dependencies when in preinstall mode.
• Download the required packages.
• Create a directory in the library path for the library and extract the packages there.
• Ensure that there are no conflicts when multiple instances are installing libraries.
  • Possibly include a lock for 'adding a library' and per-library locks.
  • An alternative simpler solution is to allow only one installation at a given time, but that is a bit limitting.
  • Clarify what it will look in the cloud.

Acceptance Criteria & Test Cases

• The above specification has been completed.
• The functionality has been unit tested to a reasonable extent.
• If possible, add an integration test similar to RuntimeStdlibTest that runs the simple server and downloads a library upon runtime's request. Ideally also testing the progress notifications.

[radeusgd]

I'm very much on the fence here with estimation - in a good scenario it should take about 4 days to do it but the locking mechanisms are often problematic so maybe 5 will be safer to account some buffer for unexpected troubles.