June 15, 2021
Recently I had a chat with two companies who asked for the same scheduling algorithm.
The solution was so easy, so I decided to use it to showcase how easy do custom scheduling for companies without using any external products, only by using one open-sourced library to interact with PagerDuty API.
Both clients have 2 teams located in different USA cities. The teams are working on different sides of the same product. So as a no-brainer, they used daily rotation. But because a lot of incidents were involved with their clients - incidents usually took a few days to resolve. And passing all information to the next on-call person inside your team is easy - just talk near a watercooler. But passing the same information to a different team was much more problematic.
The companies asked for scheduling when only developers from team A should be assigned if a week is even, and on odd weak - developers from team B. You cannot create this schedule in PagerDuty UI, it’s only possible with a use of the API. But working with the API is not so straightforward, it’s much easier to interact with a library pdscheduling where to create a schedule you just need to provide an array of assignments for every hour of the week. Take a look at full scheduling script:
import random import datetime from pdscheduling import PagerDuty team1 = ['PIMHAAA', 'BBBBB', 'CCCCC', 'DDDDD', 'EEEEEE'] team2 = ['PIMHFFF', 'GGGGG', 'HHHHH', 'IIIII', 'JJJJJ'] pd = PagerDuty("token") users = pd.get_users() date = datetime.date.today() _year, week_num, _day_of_week = date.isocalendar() if week_num % 2: active_team = team1 else: active_team = team2 schedule =  for day in range(7): user_index = (week_num * 7 + day) % len(active_team) user = active_team[user_index] for hour in range(24): schedule += [user] pd.create_or_update_schedule(name="Rotated", hours=schedule)
It’s only 20 lines of code.
Almost… You can put the script in cron on Monday. But you need to handle properly notification. Because in the script we generate and apply a schedule on Monday. Developers would be not happy to get an alert without any prior notification. The simplest solution - run the same schedule algorithm for the next week and manually email it to users.