Hostesignaler

Hostesignaler is a lightweight daemon designed for Linux and Unix-like operating systems that monitors host system metrics and emits signals when predefined thresholds are crossed. The project was first released in 2018 by a collaboration of open‑source developers working in high‑performance computing (HPC) and cloud orchestration. Hostesignaler is released under the MIT license and is actively maintained, with the latest stable release being version 1.2.4 as of 2025.

The daemon observes standard operating‑system metrics such as CPU utilization, memory pressure, disk I/O, and network bandwidth. Configuration is provided through a simple YAML file that allows users to specify thresholds for each metric, the severity level (e.g., warning or critical), and the type of notification to deliver. Supported notification mechanisms include syslog injection, D‑Bus signals, HTTP callbacks, and integration with Prometheus alerting rules. Because it runs as a background service with minimal resource overhead, hostesignaler is suitable for both single‑node environments and large node clusters.

Typical use cases include automatic job preemption in batch scheduling systems, triggering fail‑over in container orchestration platforms, and feeding real‑time host health data to monitoring dashboards. In HPC settings, hostesignaler can be wired into Slurm or Torque to abort or pause jobs that threaten host stability. In Kubernetes clusters, its D‑Bus interface can inform the API server whether a node should be marked as unschedulable.

The community around hostesignaler values clear documentation and straightforward deployment, offering Docker images and source distributions that can be installed via apt‑get or pip. Continuous integration tests run on multiple Linux distributions, ensuring compatibility across common environments. Because it operates as a first‑party monitoring component rather than an external API client, hostesignaler requires no network side‑car or more complex instrumentation, making it a lightweight alternative to larger solution suites.