Grasshopper Plugin Versioning and Migrations (thoughts)

thoughts-on-grasshopper-plugins-versioning-and-migrations.txt

Every GH Plugin has a version based on its package.json version.

When a new version of this plugin is installed 
  check the existing plugins in the DB to see if this one is allready installed, 
  
  if it is allready installed
    download the plugin into a temp dir
    look at the diff version numbers and prepare a list of migrations that need to be ran
      migrations might work like
        code looks at the migrations dir and looks for any versions between the version currently installed and the version desired.
        migrations are node files named with the version they apply to, will export a 'up' and 'down' functions that return promises.
    
    if migrations need to be run
      make a copy of the DB into a temp dir.
      put up a 'under maintenence page'
      report the migration list back to the client side. 
      run each migration in order until the latest, reporting back to the client success or failure. 
      
      if all succeed
        run the deactivate script on the old plugin version
        copy the new one into the plugins dir from the temp dir
        update the plugin version and pertinant deets in the db.
        run the activate script
        
      if any fail
        report to the client which migration failed
        restore the DB from the temp DB dir
        
        
      
    if no migrations need to be ran
      run the deactivate script on the old plugin version
      copy the new one into the plugins dir from the temp dir
      update the plugin version and pertinant deets in the db.
      run the activate script
      
  if it is not installed
    just install it like normal into the plugins dir. Save the plugin and version to the DB. Run the activation script.