[FE & BE] Docker container monitoring

[ajhollid]

Docker container monitoring is a useful feature that has been requested. On our end this would require

FE

• Updading the create uptime monitor flow to allow for a third type alongside http and ping. This type could be called docker
  • There should be a dropdown for connection type when docker type is selected
    • tcp/http
    • unix socket
  • All other fields should be the same as other uptime monitors

BE

• dockerode seems to be a good package to handle connection to Docker daemon
• If user is using tls they must provide certificates and a certificate authority. The path to these certs and authority should be placed in a default directory, with optional configuration by env var or settings from SettingsService
• The monitor should follow the typical JobQueue / StatusSerivce flow as the other uptime monitors
  • Add a new case to handle processing of results of a docker response.

Documentation

This feature requires some significant configuration on the user's end and is not suitable for non-technical users. Clear documentation is essential for user's to make use of this functionality

• It requires exposing the docker daemon over tcp, or mounting the daemon's socket to the uptime-monitor docker image.
• If the user wants to expose the daemon over tcp/http and wants to use TLS, they must generate a signing authority and SSL certificates. This is not difficult, but it requires explanation for those unfamiliar with the process.