Alertmanager vs Sensu Go
A side-by-side comparison of two self-hosted monitoring & status options — licensing, setup difficulty, resource needs, and what each one replaces.
| Feature | Alertmanager | Sensu Go |
|---|---|---|
| Deploy effort | Under-an-hour setup | Under-an-hour setup |
| Health score | 92 · Excellent | 82 · Excellent |
| Category | Monitoring & Status | Monitoring & Status |
| License | Apache-2.0 | MIT |
| Language | Go | Go |
| Setup difficulty | Medium | Medium |
| Min. RAM | 64 MB | 512 MB |
| Deployment | docker, kubernetes, binary | docker, kubernetes, binary |
| GitHub stars | ★ 8,626 | ★ 1,112 |
| First released | 2015 | 2018 |
| Replaces | PagerDuty, Opsgenie | Datadog, PagerDuty |
What are Alertmanager and Sensu Go?
Alertmanager
Alertmanager handles alerts sent by Prometheus and other clients, taking care of deduplication, grouping, and routing to receivers such as email, Slack, or PagerDuty. It also supports silences and inhibition rules.
- Alert deduplication and grouping
- Flexible routing trees
- Silences and inhibition
- Many notification integrations
Sensu Go
Sensu Go is a monitoring event pipeline that treats monitoring as code. It collects check results from agents, processes them through filters and handlers, and integrates with metrics and alerting backends.
- Monitoring as code workflow
- Event filtering and handlers
- Agent and agentless checks
- Built-in metrics support
Alertmanager vs Sensu Go: key differences
Both projects are written in Go. Licensing differs — Apache-2.0 for Alertmanager versus MIT for Sensu Go. Alertmanager is the lighter option, starting around 64 MB of RAM against 512 MB for Sensu Go. Alertmanager is the more established project (first released 2015), while Sensu Go arrived in 2018. Alertmanager has the considerably larger community, at 8,626 GitHub stars versus 1,112.
Why pick each one
Choose Alertmanager if…
- Powerful routing logic
- Standard in the Prometheus stack
Watch out for
- YAML config can get complex
- Tied to Prometheus ecosystem
Choose Sensu Go if…
- Declarative configuration
- Flexible event pipeline
Watch out for
- Smaller community after acquisition
- Concepts take time to learn
Frequently asked questions
Is Alertmanager or Sensu Go better?
Neither is universally better. Alertmanager has the larger community; both share a medium setup difficulty, so the decision comes down to features and licensing.
Are Alertmanager and Sensu Go free and open-source?
Yes. Alertmanager is licensed under Apache-2.0 and Sensu Go under MIT. Both can be self-hosted at no software cost.
Can I run Alertmanager and Sensu Go with Docker?
Alertmanager: yes. Sensu Go: yes.
Which is lighter on resources, Alertmanager or Sensu Go?
Alertmanager has the smaller minimum footprint at 64 MB of RAM, compared to about 512 MB for Sensu Go. Real-world usage depends on library size, user count, and enabled features.