Effective Incident Postmortems: Learn from Every Outage

In the world of complex systems, outages are inevitable. Even the most robust systems experience failures. When an incident occurs, the most critical action is to restore service as quickly as possible and inform stakeholders. Many tools can expedite this process, including infrastructure automation, runbooks, feature flags, and version control. However, these practices don’t delve into why the incident happened. Understanding the root cause is essential to preventing similar occurrences in the future.

What are Incident Postmortems?

An incident postmortem is a collaborative learning process that follows an incident. It involves analyzing the incident to identify the root cause. This information is then used to improve future incident response. Postmortems are not just reports; they are a chance for teams to collaboratively learn from failures and share learnings across the organization.

Why Are Incident Postmortems Important?

• Improved Documentation: Incident postmortems serve as a detailed record of the incident, ensuring its details aren’t forgotten. This documented knowledge base is invaluable for future reference. It includes not only what happened but also the steps taken for resolution, providing a roadmap for future incident mitigation.
• Trust and Transparency: Publicly posting incident postmortems builds trust and transparency with stakeholders. Customers and users appreciate knowing that steps are being taken to prevent future disruptions.
• Culture of Learning: Incident postmortems foster a culture of learning from mistakes. The focus shifts from immediate resolution to future prevention. Blameless postmortems are crucial in this aspect.
• Improved Infrastructure: Incident reports can expose weaknesses in infrastructure. By analyzing how failures occur, teams can pinpoint areas for improvement.

What Should an Incident Postmortem Include?

There’s no one-size-fits-all approach to incident postmortems. The process can vary depending on the organization’s size, culture, and the nature of the incident. Regardless of the specifics, the overall goal is to learn from the incident and make systems more resilient. Here are some common elements included in an incident postmortem:

• Summary: A high-level overview of the incident, including what happened, why it happened, the severity, and the impact on users or customers. This is particularly valuable for managers who need to communicate the incident to stakeholders.
• Causes: This section dives into the technical and operational aspects of the incident. It details the root cause, explaining how the system failed. A popular method for root cause analysis is the 5 Whys Process.
• Effects: After analyzing the root cause, the team assesses the impact on the business, services, and users. This step determines the extent and severity of the incident. For instance, a payment service outage on an e-commerce website would significantly impact customer experience.
• Resolution: This section details the incident timeline, including the time of failure, identification, resolution, and the team involved. It can also include unsuccessful troubleshooting attempts, which can be valuable references for future incidents.
• Conclusion: The conclusion outlines key takeaways, recommendations, and next steps to prevent similar incidents in the future.

Successful Incident Postmortems are Blameless

A critical factor for successful incident postmortems is a blameless environment. A culture that assigns blame discourages truthful reporting and undermines the entire purpose of the postmortem.

Blameless postmortems aim to foster a learning environment where every mistake is viewed as an opportunity to strengthen the system. The focus is on identifying the underlying causes and reasons behind outages, and implementing effective preventative measures. Many teams, including Google and Squadcast, have adopted a blameless postmortem culture to build resilience in their teams and systems.

While blameless postmortems can be challenging due to their focus on actions that led to the incident, removing blame creates a safe space for teams to openly discuss issues.

Here are some tips for conducting effective blameless incident postmortems:

1. Start with an Incident Timeline: Create a timeline of key events before the postmortem meeting, incorporating details from chat conversations and incident details. Automated timeline creation tools can streamline this process. This step establishes context for the postmortem discussion and aids in identifying root causes.
2. Postmortem Meeting: Involve everyone who was impacted by the incident in a structured and collaborative meeting. This fosters a cohesive understanding of the incident and learnings. A formal postmortem document that details the incident and resolution steps can serve as a reference for future incidents.
3. Define Roles and Owners: Designate clear roles and owners for the postmortem meeting, including a moderator to keep the discussion focused and prevent blame assigning. Guidelines for postmortem owners can ensure meetings run smoothly.
4. Prioritize Incidents: Not all incidents are equal. Establish a severity level system based on business and customer impact. Prioritize postmortems for high-severity incidents (Sev 1 or higher). For lower-severity incidents, consider automated postmortems with Incident management tools like Squadcast. However, empower teams to request postmortems for any incident if needed.
5. Capture Details: Record as much detail as possible about the incident and resolution process. This includes links to tickets, status updates, incident state documents, monitoring charts, screenshots, and relevant dashboards. Capturing these details creates a comprehensive record of the incident. Alongside these details, include key incident metrics like Mean Time to Resolution (MTTR), Service Level Objective (SLO) data, and the number of minutes of downtime. Tracking these metrics allows you to analyze incident trends over time.
6. Prompt Publication: Once the postmortem review is complete, promptly publish and distribute the final report as an internal communication, typically via email. Include the results, key learnings, and a link to the full report for all relevant stakeholders. Google recommends prompt publication because “information is fresh in the contributors’ minds.” Additionally, stakeholders are looking for explanations and reassurances. Delays can lead to speculation.

By consistently applying these practices, you can achieve better system design, reduce downtime, and create a more effective and happier engineering team.

Related Reading:

For further information on conducting effective incident postmortems, here are some recommended resources:

• Chapter 15 of the “Site Reliability Engineering” book
• An adaptation of the original Google Site Reliability Engineering book template
• A list of four templates hosted on GitHub
• Wheel of Misfortune

This blog post offers a comprehensive overview of incident postmortems, including their purpose, structure, and best practices. By following these guidelines, you can ensure that your incident postmortems are valuable learning experiences that contribute to continuous improvement.

Squadcast is an Incident Management tool that’s purpose-built for SRE. Get rid of unwanted alerts, receive relevant notifications and integrate with popular ChatOps tools. Work in collaboration using virtual incident war rooms and use automation to eliminate toil.