Your PagerDuty schedule knows who is on-call right now. Your Slack workspace does not. When an incident fires and an engineer types @sre-on-call, that mention reaches whoever was added to the Slack user group weeks ago, not necessarily the person currently on-call in PagerDuty. If those two systems are out of sync, alerts go to the wrong person and response time suffers.
Syncing PagerDuty on-call schedules to Slack user groups ensures that @sre-on-call (or any custom group) always reflects the current on-call engineer based on the live PagerDuty rotation. This guide covers why the sync matters, how to do it manually, the limitations of the manual approach, and how to automate it with a tool built specifically for this problem.
Slack user groups are named collections of Slack members that can be mentioned as a group using @groupname. When you mention @sre-on-call in any Slack channel, every member of that user group receives a notification. User groups are different from Slack channels: a channel is a place where messages are posted, while a user group is a dynamic list of people who can be tagged.
For on-call teams, user groups serve two purposes. First, they give any team member a way to reach the on-call engineer instantly without needing to check a schedule or ask who is on-call. Second, they enable automated alert routing: monitoring tools and bots can mention @sre-on-call in an alert channel and be confident the right person is notified.
The problem is that Slack user groups are static by default. Someone creates @sre-on-call and adds five engineers. The group stays the same until someone manually edits it. As the PagerDuty rotation cycles, the user group falls out of sync with reality. The only way to keep it current is to update it every time the rotation changes, or to automate the sync.
PagerDuty has a native Slack integration that can send alert notifications to Slack channels. When an incident is triggered in PagerDuty, a message is posted to a designated Slack channel. Engineers can acknowledge incidents from Slack using the PagerDuty bot.
However, PagerDuty's native Slack integration does not automatically update Slack user groups when the on-call rotation changes. The integration handles alert delivery, not schedule-to-usergroup synchronization. Keeping @sre-on-call current with the PagerDuty rotation requires a separate process.
Limitations of the native integration for user group sync:
The most straightforward approach is manual maintenance: every time the PagerDuty rotation changes, someone updates the Slack user group to reflect the new on-call engineer. In Slack, user groups are managed under People and User Groups in workspace settings. Adding or removing members from a user group takes about a minute.
In practice, manual updates fail for predictable reasons:
PagerDuty exposes a REST API that allows you to query the current on-call user for a given schedule. Slack also exposes an API for updating user group membership. A script that combines these two APIs can automatically update a Slack user group when the PagerDuty rotation changes.
A basic implementation runs on a schedule (via a cron job or serverless function) and performs these steps:
This approach works, but it has real maintenance costs: the script requires infrastructure to run reliably, needs environment variables for API keys, must handle errors when the PagerDuty or Slack API is unavailable, and needs updates whenever PagerDuty schedule IDs or Slack user group IDs change. Teams with multiple schedules and multiple user groups need a more complex script that maps each PagerDuty schedule to the corresponding Slack user group.
Pagerly automates the sync between your on-call rotation and Slack user groups without requiring any custom scripting or infrastructure. When the rotation changes (whether by the regular schedule, a cover swap, or a PagerDuty schedule override), Pagerly updates the designated Slack user group immediately. @sre-on-call always reflects the current on-call engineer.
What Pagerly's Slack usergroup sync includes:
For teams already using PagerDuty for schedule management, Pagerly acts as the Slack-native layer that makes the PagerDuty schedule visible and actionable inside Slack without requiring engineers to open the PagerDuty web interface.
| Method | User Group Auto-Updated | Covers Schedule Overrides | Channel Topic Sync | Maintenance Required |
|---|---|---|---|---|
| PagerDuty native Slack integration | No | No | No | Manual group updates |
| Manual updates | No (manual) | Often missed | No | High (every rotation change) |
| Custom API script | Yes (on cron schedule) | Partial (depends on implementation) | Requires additional code | Medium (script maintenance) |
| Pagerly | Yes (real-time) | Yes | Yes | None |
1. Sync immediately at rotation change, not on a polling interval. A cron-based sync that runs every hour means the user group can be wrong for up to an hour after a rotation handover. Real-time sync triggered by the rotation change event is always more accurate.
2. Cover schedule overrides, not just the base rotation. PagerDuty schedule overrides (when an engineer temporarily covers another's shift) should trigger a user group update the same way as a regular rotation change. Many implementations only track the base rotation and miss these one-off changes.
3. Map each rotation to a distinct user group. If your team has separate SRE and backend rotations, maintain separate user groups for each. A single @on-call group that covers multiple services creates ambiguity about which team is being notified.
4. Update the Slack channel topic alongside the user group. Engineers who arrive at an incident channel mid-incident should be able to see who is on-call from the channel topic without needing to tag the group. Channel topic sync and user group sync should happen together.
5. Test the sync after every major schedule change. After rebuilding a PagerDuty schedule or adding new team members, verify that the user group sync is still mapping correctly. A new PagerDuty user who has not been linked to their Slack account will break the sync for their shifts.
Ready to keep @sre-on-call current automatically? Pagerly syncs your PagerDuty schedule to Slack user groups in real time, with no scripts, no manual updates, and no maintenance. Get started free