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Cassandra

Cassandra

Plugin: go.d.plugin Module: cassandra

Overview

This collector gathers metrics about client requests, cache hits, and many more, while also providing metrics per each thread pool.

The JMX Exporter is used to fetch metrics from a Cassandra instance and make them available at an endpoint like http://127.0.0.1:7072/metrics.

This collector is supported on all platforms.

This collector supports collecting metrics from multiple instances of this integration, including remote instances.

Default Behavior

Auto-Detection

This collector discovers instances running on the local host that provide metrics on port 7072.

On startup, it tries to collect metrics from:

  • http://127.0.0.1:7072/metrics

Limits

The default configuration for this integration does not impose any limits on data collection.

Performance Impact

The default configuration for this integration is not expected to impose a significant performance impact on the system.

Setup

Prerequisites

Configure Cassandra with Prometheus JMX Exporter

To configure Cassandra with the JMX Exporter:

Note: paths can differ depends on your setup.

  • Download latest jmx_exporter jar file and install it in a directory where Cassandra can access it.
  • Add the jmx_exporter.yaml file to /etc/cassandra.
  • Add the following line to /etc/cassandra/cassandra-env.sh 
    JVM_OPTS="$JVM_OPTS $JVM_EXTRA_OPTS -javaagent:/opt/jmx_exporter/jmx_exporter.jar=7072:/etc/cassandra/jmx_exporter.yaml
  • Restart cassandra service.

Configuration

File

The configuration file name for this integration is go.d/cassandra.conf.

You can edit the configuration file using the edit-config script from the Netdata config directory.

cd /etc/netdata 2>/dev/null || cd /opt/netdata/etc/netdata
sudo ./edit-config go.d/cassandra.conf

Options

The following options can be defined globally: update_every, autodetection_retry.

Name Description Default Required
update_every Data collection frequency. 5 False
autodetection_retry Recheck interval in seconds. Zero means no recheck will be scheduled. 0 False
url Server URL. http://127.0.0.1:7072/metrics True
username Username for basic HTTP authentication. False
password Password for basic HTTP authentication. False
proxy_url Proxy URL. False
proxy_username Username for proxy basic HTTP authentication. False
proxy_password Password for proxy basic HTTP authentication. False
timeout HTTP request timeout. 2 False
not_follow_redirects Redirect handling policy. Controls whether the client follows redirects. False False
tls_skip_verify Server certificate chain and hostname validation policy. Controls whether the client performs this check. False False
tls_ca Certification authority that the client uses when verifying the server’s certificates. False
tls_cert Client TLS certificate. False
tls_key Client TLS key. False

Examples

Basic

A basic example configuration.

jobs:
  - name: local
    url: http://127.0.0.1:7072/metrics
HTTP authentication

Local server with basic HTTP authentication.

jobs:
  - name: local
    url: http://127.0.0.1:7072/metrics
    username: foo
    password: bar
HTTPS with self-signed certificate

Local server with enabled HTTPS and self-signed certificate.

jobs:
  - name: local
    url: https://127.0.0.1:7072/metrics
    tls_skip_verify: yes
Multi-instance

Note: When you define multiple jobs, their names must be unique.

Collecting metrics from local and remote instances.

jobs:
  - name: local
    url: http://127.0.0.1:7072/metrics

  - name: remote
    url: http://192.0.2.1:7072/metrics

Metrics

Metrics grouped by scope.

The scope defines the instance that the metric belongs to. An instance is uniquely identified by a set of labels.

Per Cassandra instance

These metrics refer to the entire monitored application.

This scope has no labels.

Metrics:

Metric Dimensions Unit
cassandra.client_requests_rate read, write requests/s
cassandra.client_request_read_latency_histogram p50, p75, p95, p98, p99, p999 seconds
cassandra.client_request_write_latency_histogram p50, p75, p95, p98, p99, p999 seconds
cassandra.client_requests_latency read, write seconds
cassandra.row_cache_hit_ratio hit_ratio percentage
cassandra.row_cache_hit_rate hits, misses events/s
cassandra.row_cache_utilization used percentage
cassandra.row_cache_size size bytes
cassandra.key_cache_hit_ratio hit_ratio percentage
cassandra.key_cache_hit_rate hits, misses events/s
cassandra.key_cache_utilization used percentage
cassandra.key_cache_size size bytes
cassandra.storage_live_disk_space_used used bytes
cassandra.compaction_completed_tasks_rate completed tasks/s
cassandra.compaction_pending_tasks_count pending tasks
cassandra.compaction_compacted_rate compacted bytes/s
cassandra.jvm_memory_used heap, nonheap bytes
cassandra.jvm_gc_rate parnew, cms gc/s
cassandra.jvm_gc_time parnew, cms seconds
cassandra.dropped_messages_rate dropped messages/s
cassandra.client_requests_timeouts_rate read, write timeout/s
cassandra.client_requests_unavailables_rate read, write exceptions/s
cassandra.client_requests_failures_rate read, write failures/s
cassandra.storage_exceptions_rate storage exceptions/s

Per thread pool

Metrics related to Cassandra’s thread pools. Each thread pool provides its own set of the following metrics.

Labels:

Label Description
thread_pool thread pool name

Metrics:

Metric Dimensions Unit
cassandra.thread_pool_active_tasks_count active tasks
cassandra.thread_pool_pending_tasks_count pending tasks
cassandra.thread_pool_blocked_tasks_count blocked tasks
cassandra.thread_pool_blocked_tasks_rate blocked tasks/s

Alerts

There are no alerts configured by default for this integration.

Troubleshooting

Debug Mode

To troubleshoot issues with the cassandra collector, run the go.d.plugin with the debug option enabled. The output should give you clues as to why the collector isn’t working.

  • Navigate to the plugins.d directory, usually at /usr/libexec/netdata/plugins.d/. If that’s not the case on your system, open netdata.conf and look for the plugins setting under [directories].

    cd /usr/libexec/netdata/plugins.d/

  • Switch to the netdata user.

    sudo -u netdata -s

  • Run the go.d.plugin to debug the collector:

    ./go.d.plugin -d -m cassandra

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