Prometheus API Ruby Client

A Ruby library for reading metrics stored on a Prometheus server.

Install

gem install prometheus-api-client

Usage

Overview

require 'prometheus/api_client'

# return a client for host http://localhost:9090/api/v1/
prometheus = Prometheus::ApiClient.client

Changing server hostname

# return a client for host http://example.com:9090/api/v1/
prometheus = Prometheus::ApiClient.client(url: 'http://example.com:9090')

Authentication proxy

If an authentication proxy ( e.g. oauth2 ) is used in a layer above the prometheus REST server, this client can use ssl and authentication headears.

# return a client for host https://example.com/api/v1/ using a Bearer token "TopSecret"
prometheus = Prometheus::ApiClient.client(url:         'https://example.com:443',
                                          credentials: { token: 'TopSecret' })

Low level calls

query

# send a low level get request to server
prometheus.get(
  'query_range',
  query: 'sum(container_cpu_usage_seconds_total' \
         '{container_name="prometheus-hgv4s",job="kubernetes-nodes"})',
  start: '2015-07-01T20:10:30.781Z',
  end:   '2015-07-02T20:10:30.781Z',
  step:  '120s',
)

# response from server is a low level response struct including
# fields like: method, body and request_headers
# usually users will not need to use this low level calls
   ...
   method=:get,
   body="{\"status\":\"success\",
   ...

High level calls

query

# send a query request to server
prometheus.query(
  query: 'sum(container_cpu_usage_seconds_total' \
         '{container_name="prometheus-hgv4s",job="kubernetes-nodes"})',
  time:  '2015-07-01T20:10:30.781Z',
)

# response from server:
{"resultType"=>"vector", "result"=>[{"metric"=>{}, "value"=>[1502350741.161, "6606.310387038"]}]}

query_range

# send a query_range request to server
prometheus.query_range(
  query: 'sum(container_cpu_usage_seconds_total' \
         '{container_name="prometheus-hgv4s",job="kubernetes-nodes"})',
  start: '2015-07-01T20:10:30.781Z',
  end:   '2015-07-02T20:10:30.781Z',
  step:  '120s',
)

# response from server:
{"resultType"=>"matrix",
 "result"=>
  [{"metric"=>
     {"__name__"=>"container_cpu_usage_seconds_total",
      "beta_kubernetes_io_arch"=>"amd64",
      "beta_kubernetes_io_os"=>"linux",
      "cpu"=>"cpu00",
      "id"=>"/",
      "instance"=>"example.com",
      "job"=>"kubernetes-cadvisor",
      "kubernetes_io_hostname"=>"example.com",
      "region"=>"infra",
      "zone"=>"default"},
    "values"=>[[1502086230.781, "51264.830099022"],
               [1502086470.781, "51277.367732154"]]},
   {"metric"=>
     {"__name__"=>"container_cpu_usage_seconds_total",
      "beta_kubernetes_io_arch"=>"amd64",
      "beta_kubernetes_io_os"=>"linux",
      "cpu"=>"cpu01",
      "id"=>"/",
      "instance"=>"example.com",
      "job"=>"kubernetes-cadvisor",
      "kubernetes_io_hostname"=>"example.com",
      "region"=>"infra",
      "zone"=>"default"},
    "values"=>[[1502086230.781, "53879.644934689"],
               [1502086470.781, "53892.665282065"]]}]}

label

# send a label request to server
prometheus.label('__name__')

# response from server:
["APIServiceRegistrationController_adds",
 "APIServiceRegistrationController_depth",
 ...

targets

# send a targets request to server
prometheus.targets()

# response from server:
{"activeTargets"=>
  [{"discoveredLabels"=>
     {"__address__"=>"10.35.19.248:8443",
      "__meta_kubernetes_endpoint_port_name"=>"https",
      "__meta_kubernetes_endpoint_port_protocol"=>"TCP",
      "__meta_kubernetes_endpoint_ready"=>"true",
      "__meta_kubernetes_endpoints_name"=>"kubernetes",
      "__meta_kubernetes_namespace"=>"default",
      "__meta_kubernetes_service_label_component"=>"apiserver",
      "__meta_kubernetes_service_label_provider"=>"kubernetes",
      "__meta_kubernetes_service_name"=>"kubernetes",
      "__metrics_path__"=>"/metrics",
      "__scheme__"=>"https",
      "job"=>"kubernetes-apiservers"},
    "labels"=>{"instance"=>"10.35.19.248:8443", "job"=>"kubernetes-apiservers"},
    "scrapeUrl"=>"https://10.35.19.248:8443/metrics",
    "lastError"=>"",
    "lastScrape"=>"2017-08-10T07:35:40.919376413Z",
    "health"=>"up"},
    ...

Tests

Install necessary development gems with bundle install and run tests with rspec:

rake