Switch to three-tier architecture

[RyanCavanaugh]

• Tier 1: git fetcher + DT parser
  • Maintains NPM cache
  • Pulls DefinitelyTyped repo every 60m at XX:30
  • Parses versions
  • Generates tarballs for changed packages
  • Uploads status (time ran, which commit, out-of-date-packages, and tarballs) to Azure storage
• Tier 2: status webpage/service
  • Exposes JSON endpoint for information generated in Tier 1
  • Exposes HTML rendering of current status for user consumption
  • Exposes history of prior statuses up to some limit
• Tier 3: publisher
  • Runs every 60m at XX:00
  • Pulls status and tarballs from Azure storage
  • Uploads them to npm
  • Reports status back to (separate) Azure storage

Benefits

• 'publisher' tier is stateless and can be run anywhere
• Expensive 'fetcher' tier doesn't need any permissions
• Website tier doesn't need any permissions
• Azure Storage can be public-readable without security concerns
• Clear and immediate visibility for PR authors