- Prometheus jmx exporter how to#
- Prometheus jmx exporter full#
java:lang:memorypool.*usagethreshold.* # Leaf attributes not interesting for us but that are presents in many path (reduce cardinality of metrics) # Unaccessible metrics (not enough privilege) The name of the label will be either # $1 from the regex below, or the entire environment variable name if no match groups are defined # Example: # additionalLabelsFromEnvvars: "^ADDL\_(.*)$" additionalLabelsFromEnvvars: ListenAddress: 0.0.0.0 listenPort: 8080 # Regular expression to match environment variables that will be added # as labels to all data points. Goods sources of information to understand what Mbeans are doing/create your dashboards are: You will get the duration of how long it took to scrape individual MBean, this is useful to understand which metrics are expansive to scrape. Java =trace -jar cassandra_exporter.jar config.yml -oneshot Run the program with the following options:
Prometheus jmx exporter how to#
In the maxScrapFrequencyInSec, you specify the metrics you want to be scraped at which frequency.īasically, starting from the set of all mbeans, the blacklist is applied first to filter this set and then the maxScrapFrequencyInSec is applied as a whitelist to filter the resulting set.Īs an example, if we take as input set the metrics 35.425000000000004 How to debug For example, mbeans endpoint from org:apache:cassandra:db.* does not expose any metrics but are used to trigger actions on Cassandra's nodes. This is important as JMX is an RPC mechanism and you don't want to trigger some of those RPC. In the blacklist block, you specify the metrics you don't want the exporter to scrape.
Prometheus jmx exporter full#
You can have a look at a full configuration file here The Cassandra exporter needs to run on every Cassandra nodes to get all the informations regarding the whole cluster. Java -jar cassandra_exporter.jar config.yml
Cassandra metrics are only available trought JMX, which in turn is only accessible with Java. Unless you have hundreds of tables, the scrap time will stay below 10sec Why the exporter is not written in GO ? So this exporter let you reach a bigger scale before you have to rely on metric aggregation in order to scale more. This exporter let you choose to not export them, which is not possible with jmx_exporter, but at the cost of a small runtime penality in order to discover them. A lot of this cardinality is due to the not too much usefulness of metrics like 999thpercentile and others. Maintainability: When your cluster grow in number of nodes, the cardinality of metrics start to put too much pressure on Prometheus itself. Why this exporter is slower than jmx_exporter ? Metrics path change between versions of cassandra and I want to avoid the hustle of having to maintain the mapping Maintainability: I want the exporter to be able to support multiple version of cassandra (2.2.X/3.X/4.X) without having to hand tune the metrics labels for each version of cassandra. Why not make more use of labels, be more prometheus way ? Not caching results mean that you can bring down your nodes by just requesting the metrics page Safety: JMX is an heayweight RPC mechanism and some cassandra metrics calls are expensive to scrap (i.e: snapshots size) as they trigger some heavy operations for cassandra. Why cache metrics results, this is not the prometheus way ? Maintainability: Upgrading the exporter should not require to restart the cassandra cluster. Safety: If there is a bug/leak in the exporter itself it should not impact cassandra. Safety: The agent share the same jvm than cassandra itself and I don't want metrics calls to be able to hammer down cassandra nodes. The project has two focus: safety and maintainability.Įvery time a tradeoff had to be made, the solution that prioritize one of those points got the advantage Why not provide the exporter as an agent for cassandra ? This decision has been taken because a lot of Apache Cassandra® metrics are expensive to scrap and can hinder the performance of the node.Īs we don't want this kind of situation to happen in production, the scrape frequency is restricted via the configuration of Cassandra Exporter. Metrics naming that respect the mbean hierarchyĪn essential design choice the project makes is to not let prometheus drive the scraping frequency. Exporting EstimatedHistogram metrics specific to Apache Cassandra®. This project is originally a fork of JMX exporter but aims at an easier integration with Apache Cassandra®. Cassandra exporter is a standalone application which exports Apache Cassandra® metrics throught a prometheus friendly endpoint.
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