Comparing Alerting Capabilities of Alertmanager with Grafana

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In the world of monitoring and observability, the ability to detect and respond to issues promptly is paramount. Alertmanager and Grafana, both deployed with SAS Viya Monitoring for Kubernetes, possess alerting capabilities. While both serve the purpose of alerting, they have distinct features and approaches that cater to different needs. In this blog post, we'll endeavour to compare Alertmanager and Grafana by their alerting functions and provide some points to consider for when you might want to use one over the other.

Alertmanager's key features

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Alertmanager is an open-source alerting tool that works seamlessly with Prometheus for a comprehensive metric-based monitoring and alerting toolkit. It is designed to handle alerts sent by client applications such as Prometheus and then manage these alerts by grouping, deduplicating, and routing them to various integrations like email, PagerDuty, Slack, and Microsoft Teams. Both are deployed together with SAS Viya Monitoring for Kubernetes. Since Alertmanager is tightly integrated with Prometheus, it leverages PromQL, Prometheus' powerful query language for defining alerting rules. This makes it easy to create sophisticated alerting conditions based on Prometheus metrics.

• Alerts are created as PrometheusRules, and evaluated against metric data stored in Prometheus. Rules use YAML; easy to use, edit, store and deploy.
• Alertmanager allows users to define complex alert routing and inhibition rules based on labels attached to alerts. This flexibility enables fine-grained control over which alerts are sent to which receivers. For more details on how the routing process works, check out thisearlier post.
• Alertmanager provides a silence mechanism that allows users to temporarily mute specific alerts or entire groups of alerts.; useful when dealing with issues and addressing underlying causes. Alerts can also be inhibited in advance during planned outages, such as during maintenance activities.
• Alertmanager can be deployed in a highly available configuration to ensure reliability. It supports clustering and replication for fault tolerance.

Grafana's key features

Grafana is a popular open-source platform for monitoring and observability that offers a wide range of features, including visualization, dashboarding, and alerting. While Grafana is primarily known for its visualization capabilities, it also provides robust alerting functions. Older versions of Grafana required alerts to be created on dashboards, which was quite restrictive. While this is still possible, the Alerting facility that is now included offers much more comprehensive and flexible capabilities.

• Grafana allows users to define alerting rules visually using its intuitive web interface. Users can set thresholds, conditions, and notification channels for triggering alerts directly in the UI (no need to write YAML or run kubectl commands).
• Grafana's alerting feature seamlessly integrates with its visualization capabilities. Users can create alerts directly from dashboards and visualize alerting states alongside other metrics.
• Grafana supports a variety of data sources; not just Prometheus. This flexibility enables users to create alerts based on data from different monitoring systems. Useful if other existing tools are already in use.
• Grafana keeps a history of triggered alerts, making it easy to track the lifecycle of alerts over time. Additionally, users can annotate graphs with alert events for better context.

Comparison

Authentication

Grafana requires users to log in with a username and password. Alertmanager has no such authentication built in; if the URL is accessible, anyone can use it. There are other ways to 'control' access to Alertmanager, but they need careful planning and consideration. Here is one example. Certainly, none are as convenient as Grafana's simple login prompt.

Ease of Use

Grafana's web interface provides an intuitive way to create and manage alerts (visually), making it more accessible to users who are not familiar with Prometheus' query language. On the other hand, Alertmanager's configuration may require more expertise due to its reliance on Prometheus' query language.

Default alerts

Prometheus includes a number of pre-defined alerts for Kubernetes applications when SAS Viya Monitoring for Kubernetes is deployed. Very useful for alerting on generally common issues, and no additional setup is required beyond defining notification channels for them. Grafana conveniently also displays these alerts, but interacting with them (e.g. silencing them when they fire) is a little less intuitive for these than it is for Grafana-managed alerts.

Integration

Both AlertManager and Grafana offer integration with various notification channels such as email, Slack, and PagerDuty. However, Grafana's integration capabilities extend beyond alerting to include visualization and dashboarding (Grafana is first a monitoring tool after all). There are also options for integrating the two together; for instance, to send Grafana-managed alerts to Alertmanager when they begin firing.

Scalability

Alertmanager can easily be scaled horizontally for high availability to handle large volumes of alerts; in fact, it's designed to be clustered. Grafana's scalability depends on the underlying data source it's connected to, but it can also scaled with a bit of effort. With SAS Viya Monitoring for Kubernetes, though, both are deployed as standalone instances by default.

Customisation

Alertmanager provides more fine-grained control over alert routing and inhibition rules, making it suitable for complex alerting workflows. It also offers options to customise nearly every aspect of the alert notifications. Grafana, on the other hand, offers greater flexibility in terms of visualization and dashboard customization, which Alertmanager lacks.

Conclusion

Both AlertManager and Grafana are powerful tools for alerting in the context of monitoring and observability. The choice between the two (or both!) depends on factors such as familiarity with Prometheus, integration and security requirements, and needs for advanced alerting features. Grafana may generally be considered more convenient for administrators with basic alerting requirements or whom are new to observability tools, whereas the expertise required to best leverage Alertmanager's powerful capabilities may be better suited to organisations that already use and have experience with it and related tools (e.g. Prometheus). Ultimately, organisations should evaluate their specific use cases and requirements to determine which tool best fits their needs.