Collect Prometheus metrics with Sensu

The Sensu Prometheus Collector is a check plugin that collects metrics from a Prometheus exporter or the Prometheus query API. This allows Sensu to route the collected metrics to one or more time series databases, such as InfluxDB or Graphite.

The Prometheus ecosystem contains a number of actively maintained exporters, such as the node exporter for reporting hardware and operating system metrics or Google’s cAdvisor exporter for monitoring containers. These exporters expose metrics that Sensu can collect and route to one or more time series databases. Sensu and Prometheus can run in parallel, complementing each other and making use of environments where Prometheus is already deployed.

This guide uses CentOS 7 as the operating system with all components running on the same compute resource. Commands and steps may change for different distributions or if components are running on different compute resources.

At the end of this guide, Prometheus will be scraping metrics. The Sensu Prometheus Collector will then query the Prometheus API as a Sensu check and send the metrics to an InfluxDB Sensu handler, which will send metrics to an InfluxDB instance. Finally, Grafana will query InfluxDB to display the collected metrics.

Set up

Install and configure Prometheus

Download and extract Prometheus:

wget https://github.com/prometheus/prometheus/releases/download/v2.6.0/prometheus-2.6.0.linux-amd64.tar.gz

tar xvfz prometheus-*.tar.gz

cd prometheus-*

Replace the default prometheus.yml configuration file with the following configuration:

global:
  scrape_interval: 15s
  external_labels:
    monitor: 'codelab-monitor'

scrape_configs:
  - job_name: 'prometheus'
    scrape_interval: 5s
    static_configs:
      - targets: ['localhost:9090']

Start Prometheus in the background:

nohup ./prometheus --config.file=prometheus.yml > prometheus.log 2>&1 &

Ensure Prometheus is running (your result may vary slightly from this example):

ps -ef | grep "[p]rometheus"
vagrant   7647  3937  2 22:23 pts/0    00:00:00 ./prometheus --config.file=prometheus.yml

Install and configure Sensu Go

Follow the RHEL/CentOS install instructions for the Sensu backend, the Sensu agent, and sensuctl.

Add an app_tier subscription to /etc/sensu/agent.yml:

subscriptions:
  - "app_tier"

Restart the Sensu agent to apply the configuration change:

sudo systemctl restart sensu-agent

Ensure Sensu services are running:

systemctl status sensu-backend
systemctl status sensu-agent

Install and configure InfluxDB

Add an InfluxDB repo:

echo "[influxdb]
name = InfluxDB Repository - RHEL \$releasever
baseurl = https://repos.influxdata.com/rhel/\$releasever/\$basearch/stable
enabled = 1
gpgcheck = 1
gpgkey = https://repos.influxdata.com/influxdb.key" | sudo tee /etc/yum.repos.d/influxdb.repo

Install InfluxDB:

sudo yum -y install influxdb

Open /etc/influxdb/influxdb.conf and uncomment the http API line:

[http]
  # Determines whether HTTP endpoint is enabled.
  enabled = true

Start InfluxDB:

sudo systemctl start influxdb

Add the Sensu user and database:

influx -execute "CREATE DATABASE sensu"

influx -execute "CREATE USER sensu WITH PASSWORD 'sensu'"

influx -execute "GRANT ALL ON sensu TO sensu"

Install and configure Grafana

Install Grafana:

sudo yum install -y https://s3-us-west-2.amazonaws.com/grafana-releases/release/grafana-5.1.4-1.x86_64.rpm

Change Grafana’s listen port so that it does not conflict with the Sensu web UI:

sudo sed -i 's/^;http_port = 3000/http_port = 4000/' /etc/grafana/grafana.ini

Create a /etc/grafana/provisioning/datasources/influxdb.yaml file, and add an InfluxDB data source:

apiVersion: 1

deleteDatasources:
  - name: InfluxDB
    orgId: 1

datasources:
  - name: InfluxDB
    type: influxdb
    access: proxy
    orgId: 1
    database: sensu
    user: grafana
    password: grafana
    url: http://localhost:8086

Start Grafana:

sudo systemctl start grafana-server

Create a Sensu InfluxDB pipeline

Create a Sensu InfluxDB handler asset

Put the following asset definition in a file called asset_influxdb:

type: Asset
api_version: core/v2
metadata:
  name: sensu-influxdb-handler
  namespace: default
spec:
  sha512: 612c6ff9928841090c4d23bf20aaf7558e4eed8977a848cf9e2899bb13a13e7540bac2b63e324f39d9b1257bb479676bc155b24e21bf93c722b812b0f15cb3bd
  url: https://assets.bonsai.sensu.io/b28f8719a48aa8ea80c603f97e402975a98cea47/sensu-influxdb-handler_3.1.2_linux_amd64.tar.gz
{
  "type": "Asset",
  "api_version": "core/v2",
  "metadata": {
    "name": "sensu-influxdb-handler",
    "namespace": "default"
  },
  "spec": {
    "sha512": "612c6ff9928841090c4d23bf20aaf7558e4eed8977a848cf9e2899bb13a13e7540bac2b63e324f39d9b1257bb479676bc155b24e21bf93c722b812b0f15cb3bd",
    "url": "https://assets.bonsai.sensu.io/b28f8719a48aa8ea80c603f97e402975a98cea47/sensu-influxdb-handler_3.1.2_linux_amd64.tar.gz"
  }
}

Create a Sensu handler

Put the following handler definition in a file called handler:

type: Handler
api_version: core/v2
metadata:
  name: influxdb
  namespace: default
spec:
  command: "sensu-influxdb-handler -a 'http://127.0.0.1:8086' -d sensu -u sensu -p sensu"
  timeout: 10
  type: pipe
  runtime_assets:
  - sensu-influxdb-handler
{
  "type": "Handler",
  "api_version": "core/v2",
  "metadata": {
    "name": "influxdb",
    "namespace": "default"
  },
  "spec": {
    "command": "sensu-influxdb-handler -a 'http://127.0.0.1:8086' -d sensu -u sensu -p sensu",
    "timeout": 10,
    "type": "pipe",
    "runtime_assets": [
      "sensu-influxdb-handler"
    ]
  }
}

PRO TIP: sensuctl create -f also accepts files that contain multiple resources’ definitions.

Use sensuctl to add the handler and the asset to Sensu:

sensuctl create --file handler --file asset_influxdb

Collect Prometheus metrics with Sensu

Create a Sensu Prometheus Collector asset

Put the following handler definition in a file called asset_prometheus:

type: Asset
api_version: core/v2
metadata:
  name: sensu-prometheus-collector
  namespace: default
spec:
  url: https://assets.bonsai.sensu.io/ef812286f59de36a40e51178024b81c69666e1b7/sensu-prometheus-collector_1.1.6_linux_amd64.tar.gz
  sha512: a70056ca02662fbf2999460f6be93f174c7e09c5a8b12efc7cc42ce1ccb5570ee0f328a2dd8223f506df3b5972f7f521728f7bdd6abf9f6ca2234d690aeb3808
{
  "type": "Asset",
  "api_version": "core/v2",
  "metadata": {
    "name": "sensu-prometheus-collector",
    "namespace": "default"
  },
  "spec": {
    "url": "https://assets.bonsai.sensu.io/ef812286f59de36a40e51178024b81c69666e1b7/sensu-prometheus-collector_1.1.6_linux_amd64.tar.gz",
    "sha512": "a70056ca02662fbf2999460f6be93f174c7e09c5a8b12efc7cc42ce1ccb5570ee0f328a2dd8223f506df3b5972f7f521728f7bdd6abf9f6ca2234d690aeb3808"
  }
}

Add a Sensu check to complete the pipeline

Create the following check definition in a file called check:

type: CheckConfig
api_version: core/v2
metadata:
  name: prometheus_metrics
  namespace: default
spec:
  command: "sensu-prometheus-collector -prom-url http://localhost:9090 -prom-query up"
  handlers:
  - influxdb
  interval: 10
  publish: true
  output_metric_format: influxdb_line
  output_metric_handlers: []
  subscriptions:
  - app_tier
  timeout: 0
  runtime_assets:
  - sensu-prometheus-collector
{
  "type": "CheckConfig",
  "api_version": "core/v2",
  "metadata": {
    "name": "prometheus_metrics",
    "namespace": "default"
  },
  "spec": {
    "command": "sensu-prometheus-collector -prom-url http://localhost:9090 -prom-query up",
    "handlers": [
      "influxdb"
    ],
    "interval": 10,
    "publish": true,
    "output_metric_format": "influxdb_line",
    "output_metric_handlers": [],
    "subscriptions": [
      "app_tier"
    ],
    "timeout": 0,
    "runtime_assets": [
      "sensu-prometheus-collector"
    ]
  }
}

Use sensuctl to add the check to Sensu:

sensuctl create --file check --file asset_prometheus

Open the Sensu web UI to see the events generated by the prometheus_metrics check. Visit http://127.0.0.1:3000, and log in as the admin user (created during the initialization step when you installed the Sensu backend).

You can also see the metric event data using sensuctl.

sensuctl event list
    Entity            Check                                          Output                                   Status   Silenced             Timestamp            
────────────── ──────────────────── ──────────────────────────────────────────────────────────────────────── ──────── ────────── ─────────────────────────────── 
sensu-centos   keepalive            Keepalive last sent from sensu-centos at 2019-02-12 01:01:37 +0000 UTC        0   false      2019-02-12 01:01:37 +0000 UTC  
sensu-centos   prometheus_metrics   up,instance=localhost:9090,job=prometheus value=1 1549933306                  0   false      2019-02-12 01:01:46 +0000 UTC

Visualize metrics with Grafana

Configure a dashboard in Grafana

Download the Grafana dashboard configuration file from the Sensu docs:

wget https://docs.sensu.io/sensu-go/latest/files/up_or_down_dashboard.json

Using the downloaded file, add the dashboard to Grafana with an API call:

curl  -XPOST -H 'Content-Type: application/json' -d@up_or_down_dashboard.json HTTP://admin:admin@127.0.0.1:4000/api/dashboards/db

View metrics in Grafana

Confirm metrics in Grafana: login at http://127.0.0.1:4000. Use admin for both username and password.

Click Home in the upper left corner, then click the Up or Down Sample 2 dashboard. You should see a graph with initial metrics, similar to:

up_or_down_detail

Next steps

You should now have a working set-up with Prometheus scraping metrics. The Sensu Prometheus Collector runs via a Sensu check and collects metrics from the Prometheus API. The metrics are handled by the InfluxDB handler, sent to InfluxDB, and visualized by a Grafana dashboard.

You can plug the Sensu Prometheus Collector into your Sensu ecosystem. Use Prometheus to gather metrics and use Sensu to send them to the proper final destination. Prometheus has a comprehensive list of additional exporters to pull in metrics.