Watcher: Switch to pagerduty API V2

[spinscale]

Watcher is currently using the v1 API events endpoint, available under https://v1.developer.pagerduty.com/documentation/events

This is however decommissioned at the 19th of October, so we have to switch to V2 API as soon as possible.

More info under https://v2.developer.pagerduty.com/

[elasticmachine]

Pinging @elastic/es-core-infra

[jasontedor]

If I read this correctly:

On April 24, 2018, at 22:00 PDT (UTC+7), our v1 REST API is entering a decommissioning period. Starting on that date, you will no longer be able to generate v1 REST API keys, but the v1 REST API will remain operational.

it implies that new users would not be able to use our PagerDuty integration today.

[hub-cap]

So after finishing the PR, I got to reading the actual docs here. Look at the gem I found.

WILL THE V1 EVENTS API STILL BE SUPPORTED?
This change only affects the v1 REST API. You can continue to use the v1 Events API as you do today.Learn more about our the differences between our APIs here.

This comes directly from the linked doc in the issue description. The only place we use the PagerDuty API is here, and for brevity ill include the 2 lines below.

    static final String HOST = "events.pagerduty.com";
    static final String PATH = "/generic/2010-04-15/create_event.json";

This means we are only using the Events API, and yes we are still using the V1 Events API, which will not be affected by this.

The good news is that we can still migrate to the V2 Events API. PagerDuty has a V2 Events API already. The work is done in the PR attached to this issue. I am not sure this warrants a blocker / critical status anymore though.