add oneoff script for incrementally migrating users to multi auth

bin/oneoff/migrate_users_to_multi_auth.rb

@@ -0,0 +1,32 @@
+#!/usr/bin/env ruby
+
+require_relative '../../dashboard/config/environment'
+
+SLICE_SIZE = 1_000
+
+def migrate_batches(limit=nil)
+  limit = limit.to_i if limit
+  unmigrated_users = User.where.not(provider: User::PROVIDER_MIGRATED)
+  unmigrated_users_count = 40_000_000 # estimate
+
+  slice_count = 0
+  puts "Migrating #{limit || 'all'} slice(s)"
+  unmigrated_users.each_slice(SLICE_SIZE) do |slice|
+    puts "\tSLICE_COUNT: #{slice_count + 1} of ~#{unmigrated_users_count / SLICE_SIZE}..."
+    ActiveRecord::Base.transaction do
+      successes = 0
+      slice.each do |user|
+        user.migrate_to_multi_auth
+        successes += 1 if user.valid? && user.provider == User::PROVIDER_MIGRATED
+      end
+      puts "\t\tsuccessful migrations: #{successes} / #{SLICE_SIZE}"
+    end
+    slice_count += 1
+
+    if limit && slice_count >= limit
+      break
+    end
+  end
+end
+
+migrate_batches(*ARGV)