Getting started with monitoring

Configuring metrics

To configure metrics, use the metrics section in a cluster configuration. The configuration below enables all metrics excluding vinyl-specific ones:

metrics:
  include: [ all ]
  exclude: [ vinyl ]
  labels:
    alias: '{{ instance_name }}'

The metrics.labels option accepts the predefined {{ instance_name }} variable. This adds an instance name as a label to every observation.

Third-party Lua modules, like crud or expirationd, offer their own metrics. You can enable these metrics by configuring the corresponding role. The example below shows how to enable statistics on called operations by providing the roles.crud-router role’s configuration:

roles:
- roles.crud-router
- roles.metrics-export
roles_cfg:
  roles.crud-router:
    stats: true
    stats_driver: metrics
    stats_quantiles: true

expirationd metrics can be enabled as follows:

expirationd:
  cfg:
    metrics: true

Exposing metrics

To expose metrics in different formats, you can use a third-party metrics-export-role role. In the following example, the metrics of storage-a-001 are provided on two endpoints:

• /metrics/prometheus: exposes metrics in the Prometheus format.
• /metrics/json: exposes metrics in the JSON format.

storage-a-001:
  roles_cfg:
    roles.metrics-export:
      http:
      - listen: '127.0.0.1:8082'
        endpoints:
        - path: /metrics/prometheus/
          format: prometheus
        - path: /metrics/json
          format: json

Example on GitHub: sharded_cluster_crud_metrics

Creating custom metrics

The metrics module allows you to create and collect custom metrics. The example below shows how to collect the number of data operations performed on the specified space by increasing a counter value inside the on_replace() trigger function:

local metrics = require('metrics')
local bands_replace_count = metrics.counter('bands_replace_count', 'The number of data operations')
local trigger = require('trigger')
trigger.set(
        'box.space.bands.on_replace',
        'update_bands_replace_count_metric',
        function(_, _, _, request_type)
            bands_replace_count:inc(1, { request_type = request_type })
        end
)

Learn more in Custom metrics.

Collecting metrics

When metrics are configured and exposed, you can use the desired third-party tool to collect them. Below is the example of a Prometheus scrape configuration that collects metrics of multiple Tarantool instances:

global:
  scrape_interval:     5s
  evaluation_interval: 5s

scrape_configs:
  - job_name: prometheus
    static_configs:
      - targets:
          - 127.0.0.1:8081
          - 127.0.0.1:8082
          - 127.0.0.1:8083
          - 127.0.0.1:8084
          - 127.0.0.1:8085
    metrics_path: "/metrics/prometheus"

For more information on collecting and visualizing metrics, refer to Grafana dashboard.