Add live status checks on talisker.run

[maxiberta]

It'd be great if there was something similar to taliskers's /_status/, /_status/info/, /_status/test, etc API when running a service through talisker.run. Maybe a command line flag, or envvars?

[bloodearnest]

I'm not sure how this could work, tbh.

I mean, you could have an envvar like TALISKER_STATUS_CMD=test, and then instead of running the supplied script, it would run the cmd and output the response?

I think maybe we could have a talisker.test command, which does the same thing talisker.run, but has subcommands, and checks that the current configuration in the environment works. e.g

talisker.test statsd  # sends statsd metric
talisker.test sentry  # sends test sentry report
talisker.test config  # shows parsed talisker config

What your testing is that your talisker config (via envvar or file) is functioning as expected? Is that what you were thinking?

[maxiberta]

That'd be great to check the environment health. I'd call it talisker.status or something other than .test to prevent confusion with unit tests.
Additionally, I was thinking that the app itself could optionally implement some predefined subcommand, such as myapp selfcheck with arbitrary logic that exits with 0 if it passes.

[maxiberta]

So that talisker.status selfcheck would call myapp selfcheck and fail if it didn't exit with 0, with a message such as App failed to run selfcheck. The actual app output would be helpful as well (both on success or failure).