First milestone

[koenw]

• Github PR comment listener
  • Github webhook secret authentication
  • Whitelist of allowed repositories (everything under paritytech?)
  • User authorization (should be part of the org in order to run it)
• Shared incoming job queue
  • Long-polling
  • Exponential backoff
  • Authentication
  • Peer discovery through DNS SRV records
• Job execution
  • Checkout & prepare git repository
  • Load rhai script from repository
  • Run script
    • Pass extra arguments to script
    • Provide API to commit/push any output files
    • Provide API to run cargo
    • Provide API to comment on issue
    • Use Linux Namespaces (e.g. using unshare) to isolate the script and cargo from the rest of the system
• Runtime configuration
  • Command-line and environment variable configuration
    • Github webhook secret
    • Listen address & port
    • Log-level (debug,info,warn,error)
    • repository root directory
    • bot command prefix (e.g. /bench-bot)
    • DNS SRV Record Name (e.g. benchbot.opstooling.parity.io)
  • Command-line --help option