Allow custom healthcheck URL

[karan]

I use a self-hosted HC instance and would like to use that for monitoring gphotos-sync.

It'll be more flexible if HEALTHCHECK_ID was instead HEALTHCHECK_URL.

[JakeWharton]

It used to be URL but then it felt weird to just append /start and hope it would work. Since this isn't common, I would prefer to add HEALTHCHECK_HOST where you can specify a host and port. Is that enough for you?

I was actually talking to someone else about this last week...

[karan]

Yeah that would work as an override (though I personally find the whole URL as more flexible).

[JakeWharton]

We could allow specifying two full URLs then, at the expense of you having to specify the full /start URL and the regular one. This would also make it agnostic to the provider of the health check since presumably there are other services which do similar things, although you have no way of controlling the body or headers of the requests.

[karan]

That'd be fine although a bit too verbose. A couple of other options:

• Keep 1 URL, assume that URL the URL is a HC URL and follows their spec. /start and all.
• Keep 1 URL, and a IS_HEALTHCHECK_API bool. That being true would make it so we can use the /start API.

[issmirnov]

+1 to HEALTHCHECK_HOST. I was about to open a PR when I saw this issue.

[issmirnov]

Thank you! Confirmed working.

Note to other passing users: reminder that unless you have a redirect setup on a root domain, you probably want to set https://your.domain.com/ping as the healthcheck host, not just https://your.domain.com