*: auto config reloading

[jwhitcraft]

Is your feature request related to a problem? Please describe.
Currently if you change the yaml config for the sso-proxy, you have to reload the sso-proxy app itself.

Describe the solution you'd like

• The sso-proxy should allow for the config file to change, and reload it automatically, so you don't have to reload the sso-proxy every time. This is useful for dynamic environments and when running in kubernetes.

• Provide a way when running in a kubernetes cluster to have it watch for annotations on a service to have it dynamically generate the config and reload the service when the config is updated.

[snebel29]

Hi,
In fact I came back with this same idea for bitly/oauth2_proxy then switched over buzzfeed/sso as the former seems to have been deprecated, I've already started working in a sidecar binary that would watch for kubernetes annotated services to then change the upstream configuration file within the filesystem, but this still will take some time to get something working, to avoid restarting processes, upstream config reloading would be a healthy requirement.

To do so I was thinking on using either SIGHUP or SIGUSR1 to signal to sso-proxy process about the new configuration to be load, how does that sound? is that something that if I pull request, would be accepted?

Cheers

[mreiferson]

@jwhitcraft similar to @snebel29's suggestion, there are a number of tools available to provide this functionality independent from sso itself (like confd). I wonder if this kind of functionality ultimately belongs in the "core"?