Sensu Go

sensu-go-notes.md

References

https://docs.sensu.io/sensu-go/5.2/

https://blog.sensu.io/alert-fatigue-part-1-avoidance-and-course-correction

Subscribe agent to checks

agent configuration

On the host running the agent; edit the subscriptions to match the desired checks.

sudo vi /etc/sensu/agent.yml

# agent configuration
##
name: "server.example.com"
namespace: "default"
subscriptions:
  - linux
  - cpu

sudo systemctl restart sensu-agent

round robin checks

In Sensu core, adding the prefix "roundrobin:" to the subscription will make it a round robin check. E.g. roundrobin:webserver.

See round_robin on https://docs.sensu.io/sensu-go/5.3/reference/checks/#spec-attributes

Sensu-core docs: https://docs.sensu.io/sensu-core/1.1/reference/clients/#round-robin-client-subscriptions

Publish / Unpublish checks

Published checks are run on a schedule by the sensu scheduler.

Un-published checks are ignored by the scheduler, but they can be run on demand using the API or by another check as part of it's remediation configuration. See automating triage

Firewall ports

The Sensu backend uses:

• 2379 (HTTP/HTTPS) Sensu storage client: Required for Sensu backends using an external etcd instance
• 2380 (HTTP/HTTPS) Sensu storage peer: Required for other Sensu backends in a cluster
• 3000 (HTTP/HTTPS) Sensu dashboard: Required for all Sensu backends using a Sensu dashboard
• 8080 (HTTP/HTTPS) Sensu API: Required for all users accessing the Sensu API
• 8081 (WS/WSS) Agent API: Required for all Sensu agents connecting to a Sensu backend

The Sensu agent uses:

• 3030 (TCP/UDP) Sensu agent socket: Required for Sensu agents using the agent socket
• 3031 (HTTP) Sensu agent API: Required for all users accessing the agent API
• 8125 (UDP, TCP on Windows) StatsD listener: Required for all Sensu agents using the StatsD listener

source

Sensu checks

Bonsai is the registry of checks and handlers.

Create check from a script

sudo curl https://raw.githubusercontent.com/sensu-plugins/sensu-plugins-cpu-checks/03a99bab0237c81121ce702b0c5a5a3b44908535/bin/check-cpu.sh \
-o /usr/local/bin/check-cpu.sh && \
sudo chmod +x /usr/local/bin/check-cpu.sh

sensuctl check create check-cpu \
--command 'check-cpu.sh -w 75 -c 90' \
--interval 60 \
--subscriptions linux

source

Monitor an external resource (proxy entity)

sudo curl https://raw.githubusercontent.com/sensu/sensu-go/5.1.0/examples/checks/http_check.sh \
-o /usr/local/bin/http_check.sh && \
sudo chmod +x /usr/local/bin/http_check.sh

check.json

{
  "type": "CheckConfig",
  "api_version": "core/v2",
  "metadata": {
    "name": "check-http",
    "namespace": "default"
  },
  "spec": {
    "command": "http_check.sh https://sensu.io",
    "interval": 60,
    "proxy_entity_name": "sensu-site",
    "publish": true,
    "subscriptions": [
      "proxy"
    ]
  }
}

sensuctl create --file check.json

Add the subscription to an agent.

subscriptions:
  - "proxy"

sudo service sensu-agent restart

source

Sensu ruby plugin install

https://packagecloud.io/sensu/community

curl -s https://packagecloud.io/install/repositories/sensu/community/script.rpm.sh | sudo bash

sudo yum install sensu-plugins-ruby-0.2.0-1.el7.x86_64