Make the command easy to manage and run in the dedicated machine

[joao-paulo-parity]

Primarily due to https://github.com/paritytech/substrate/pull/8699#issuecomment-831967902 I had to create a dedicated user account for running the benchbot, set up the user's environment, install Rust, etc. Now instead of being owned by an arbitrary user, any sudo user can execute the relevant commands with sudo -u benchbot [cmd].

Current

• For starting the bot (note: you can just ctrl-c after, the command will still be running there):

ssh user@remote 'sudo -u benchbot bash -c "cd ~/bench-bot && source ~/.cargo/env && yarn start"'

• For stopping the bot:

ssh user@remote 'sudo pkill -u benchbot'

• Restart by combining the two commands above, i.e.

ssh user@remote 'sudo pkill -u benchbot && sudo -u benchbot bash -c "cd ~/bench-bot && source ~/.cargo/env && yarn start"'

Future improvements

• [x] Manage the execution through a systemd service so that it can be trivially restarted, stopped, started, etc
• [x] Log to systemd journal so that it can be aggregated with Loki (https://github.com/paritytech/devops/issues/921)
• [x] Create helper sub-commands to manage the bot
  • [x] start, restart, stop can be just wrappers to systemd
  • [x] update to pull a branch and automatically restart the bot e.g. bench-bot-manager update master
• [x] Script to bootstrap the bot from scratch
  • Create and setup benchbot user
  • Install Rust and the required toolchains for Substrate (reference: https://getsubstrate.io)
  • Create and enable systemd service
  • Start the bot (i.e. start systemd service)