collectd

A daemon that collects system performance statistics periodically, and provides tons of plugins to store and analyze these values

     

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jclouds

A Java Library for controlling cloud resources, with various plugins for many popular cloud providers.

     

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jmxtrans

Plugs Java VM statistics via JMX to various backend monitoring tools

     

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Logstash

A modern tool for managing events and logs, with an ElasticSearch backend which allows a high degree of searching and filtering. It includes a shipper in remote systems, indexer in the aggregator machine, and a Web UI.

     

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Metrics

Captures JVM and application-level metrics for Java

     

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Pallet

A tool to provision and maintain servers across various cloud platforms as well as virtual machine platforms, without any dependencies. Provides cloud and operating system independence.

     

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Sentry

Automate error tracking to find and fix issues before your users even experience a crash. Sentry is open-source, real-time, and loved by 100,000 developers around the world.

     

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Zabbix

An open source, enterprise-class monitoring framework

     

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