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.

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.

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.

The file format is YAML. Generally, the structure is:

update_every: 1
autodetection_retry: 0
jobs:
  - name: some_name1
  - name: some_name1

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.

Config options

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

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.

Config

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.

Config

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.

Config

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

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

Troubleshooting

Debug Mode

Important: Debug mode is not supported for data collection jobs created via the UI using the Dyncfg feature.

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

  To debug a specific job:

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

Getting Logs

If you're encountering problems with the cassandra collector, follow these steps to retrieve logs and identify potential issues:

• Run the command specific to your system (systemd, non-systemd, or Docker container).
• Examine the output for any warnings or error messages that might indicate issues. These messages should provide clues about the root cause of the problem.

System with systemd

Use the following command to view logs generated since the last Netdata service restart:

journalctl _SYSTEMD_INVOCATION_ID="$(systemctl show --value --property=InvocationID netdata)" --namespace=netdata --grep cassandra

System without systemd

Locate the collector log file, typically at /var/log/netdata/collector.log, and use grep to filter for collector's name:

grep cassandra /var/log/netdata/collector.log

Note: This method shows logs from all restarts. Focus on the latest entries for troubleshooting current issues.

Docker Container

If your Netdata runs in a Docker container named "netdata" (replace if different), use this command:

docker logs netdata 2>&1 | grep cassandra