Sloth is a Prometheus SLO (Service Level Objectives) generator written in Go that automates the creation of SLO metrics and alerting rules. The project is actively maintained and in continuous development, with the maintainer currently working on internal improvements to enhance extensibility and adaptability for real-world use cases. The tool generates understandable, uniform, and reliable Prometheus SLOs for any kind of service using a simple SLO specification that produces multiple metrics and multi-window multi-burn alerts.
The core functionality of Sloth centers on automating what would otherwise be manual SLO configuration. It autogenerates Prometheus SLI recording rules across different time windows, creates SLO metadata rules, and produces multi-window multi-burn alert rules for both page and warning severity levels. The implementation is based on Google's SLO methodology and the multi-window multi-burn alerting framework. Sloth validates SLO specifications and includes a validate command specifically designed for GitOps and CI integration, allowing teams to enforce SLO standards across their infrastructure.
The tool offers significant customization capabilities, including label customization and the ability to disable specific alert types. It provides a single uniform way of creating SLOs across different services and teams, which addresses a common pain point in organizations managing multiple services. Sloth automatically generates Grafana dashboards to visualize SLO state, making it easy for teams to monitor their service level objectives at a glance. The project is distributed as a single binary with an easy-to-use CLI interface, reducing deployment complexity.
Sloth supports multiple deployment and integration modes. It works with Kubernetes through Prometheus-operator support and includes a Kubernetes Controller/operator mode with Custom Resource Definitions for native Kubernetes integration. The tool supports different SLI types and includes a plugin system for custom SLI implementations. A separate repository containing common SLI plugins is available for teams looking for pre-built integrations. Additionally, Sloth supports the OpenSLO standard, providing interoperability with other SLO tools and frameworks.
The project includes safe default SLO period windows for both 30 and 28-day cycles, with customizable windows available for advanced use cases. According to GitGenius activity tracking, the repository has a median issue and pull request response latency of approximately 14,861 hours across 70 tracked items. The primary maintainer, slok, has been highly active with 132 recorded events, while contributors cxdy and kaitimmer have each contributed 7 events. The most frequently applied issue label is stale with 29 occurrences, followed by bug with 2 occurrences. The repository shares overlapping contributors with vercel/turborepo, prometheus-community/helm-charts, and argoproj/argo-cd, indicating cross-pollination within the cloud-native ecosystem. Documentation is comprehensive and available at sloth.dev, with specific sections covering usage examples, SLI plugins, and development guidelines in the CONTRIBUTING.md file.
