Switch to using agenda for scheduling

[orta]

So we can do "in one week" or whatever

• https://www.npmjs.com/package/agenda#manually-working-with-a-job
• https://github.com/agenda/human-interval

[orta]

An ideal API, expanding on this Dangerfile from the Artsy Peril setup for new RFCs.

import { danger } from "danger"
import { IncomingWebhook } from "@slack/client"
import { Issues } from "github-webhook-event-types"

declare const peril: any // danger/danger#351

const gh = (danger.github as any) as Issues
const issue = gh.issue

if (issue.title.includes("RFC:")) {
  var url = peril.env.SLACK_RFC_WEBHOOK_URL || ""
  var webhook = new IncomingWebhook(url)
  webhook.send({})

  // Remind us halfway, and at the end of the week to write comments
  peril.runTask('mid_week_rfc_notification', 'in 3 days', issue)
  peril.runTask('end_of_week_rfc_notification', 'in 7 days', issue)
}

This would be hooked up inside the peril settings, where you can define your tasks and their corresponding files:

{
  "rules": {
    "pull_request": "artsy/artsy-danger@org/all-prs.ts",
    "pull_request.closed": "artsy/artsy-danger@org/closed-prs.ts"
  },
  "repos": {
    "artsy/reaction": {
      "pull_request": "danger/pr.ts"
  },
  "tasks": {
    "mid_week_rfc_notification": "artsy/artsy-danger@tasks/rfc/mid_week.ts",
    "end_of_week_rfc_notification": "artsy/artsy-danger@tasks/rfc/mid_week.ts"
  }
}

Here's an example task: tasks/rfc/mid_week.ts

import { peril } from "danger"
import { IncomingWebhook } from "@slack/client"
import { Issues } from "github-webhook-event-types"

const issue = peril.data as Issues

var url = peril.env.SLACK_RFC_WEBHOOK_URL || ""
var webhook = new IncomingWebhook(url)
webhook.send({ // in 3 days etc })

the issue JSON is passed from the peril.schedule to peril.data.

[orta]

Under the hood:

Today: peril.schedule could make those calls directly to the peril internals.

In the future: is going to have to send something back to the host process.

It's probably better to make the scheduler a separate API route POST, it should take a task name, an interval and some dumb json data. Under the hood it can call

agenda.schedule('3 days', 'runDangerTask', { name: "mid_week_rfc_notification", data: issue });

Which can get hooked up to a generic task runner inside Peril.