Sensu is often described as the “monitoring router”. Essentially, Sensu takes the results of “check” scripts run across many systems, and if certain conditions are met; passes their information to one or more “handlers”. Checks are used, for example, to determine if a service like Apache is up or down. Checks can also be used to collect data, such as MySQL query statistics or Rails application metrics. Handlers take actions, using result information, such as sending an email, messaging a chat room, or adding a data point to a graph. There are several types of handlers, but the most common and most powerful is “pipe”, a script that receives data via standard input. Check and handler scripts can be written in any language, and the community repository continues to grow! In this documentation, I will show how to install Sensu on CentOS 6.

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Generate SSL certificates for communication of Sensu components (be sure that OpenSSL is installed)

which openssl
openssl version
cd /tmp
wget http://sensuapp.org/docs/0.16/tools/ssl_certs.tar
tar -xvf ssl_certs.tar
cd ssl_certs
./ssl_certs.sh generate

Install RabbitMQ (requires Erlang from EPEL repository)

sudo rpm -Uvh http://dl.fedoraproject.org/pub/epel/6/i386/epel-release-6-8.noarch.rpm
sudo yum install erlang
sudo rpm --import http://www.rabbitmq.com/rabbitmq-signing-key-public.asc
sudo rpm -Uvh http://www.rabbitmq.com/releases/rabbitmq-server/v3.4.4/rabbitmq-server-3.4.4-1.noarch.rpm
sudo chkconfig rabbitmq-server on
sudo service rabbitmq-server start

Configure RabbitMQ SSL listenet

sudo mkdir -p /etc/rabbitmq/ssl
sudo cp /tmp/sensu_ca/cacert.pem /etc/rabbitmq/ssl/
sudo cp /tmp/server/cert.pem /etc/rabbitmq/ssl/
sudo cp /tmp/server/key.pem /etc/rabbitmq/ssl/
sudo vi /etc/rabbitmq/rabbitmq.config

[
{rabbit, [
{ssl_listeners, [5671]},
{ssl_allow_poodle_attack, true},
{ssl_options, [{cacertfile,"/etc/rabbitmq/ssl/cacert.pem"},
                {certfile,"/etc/rabbitmq/ssl/cert.pem"},
                {keyfile,"/etc/rabbitmq/ssl/key.pem"},
                {verify,verify_peer},
                {fail_if_no_peer_cert,true}]}
    ]}
].

sudo service rabbitmq-server restart

Create a RabbitMQ vhost for Sensu

sudo rabbitmqctl add_vhost /sensu

Create a RabbitMQ user with permissions for the Sensu vhost

sudo rabbitmqctl add_user <rabbitmq-user> <rabbitmq-password>

Create a RabbitMQ user with permissions for the Sensu vhost

sudo rabbitmqctl set_permissions -p /sensu sensu ".*" ".*" ".*"

(Optional) Enable the RabbitMQ web management console

sudo rabbitmq-plugins enable rabbitmq_management

Install Redis (you can use tutorial in this page) Add Sensu repository

sudo vi /etc/yum.repos.d/sensu.repo

[sensu]
name=sensu-main
baseurl=http://repos.sensuapp.org/yum/el/$releasever/$basearch/
gpgcheck=0
enabled=1

Install Sensu using yum

sudo yum install sensu

Add Sensu SSL certificates

 sudo mkdir -p /etc/sensu/ssl
 sudo cp /tmp/ssl_certs/client/cert.pem /etc/sensu/ssl/
 sudo cp /tmp/ssl_certs/client/key.pem /etc/sensu/ssl/

Configure Sensu to communicate with RabbitMQ

sudo vi /etc/sensu/conf.d/rabbitmq.json

{
    "rabbitmq": {
    "ssl": {
      "cert_chain_file": "/etc/sensu/ssl/cert.pem",
      "private_key_file": "/etc/sensu/ssl/key.pem"
    },
    "host": "<rabbitmq-ip>",
    "port": 5671,
    "vhost": "/sensu",
    "user": "<rabbitmq-user>",
    "password": "<rabbitmq-password>"
  }
}

Configure Sensu to communicate with Redis

sudo vi /etc/sensu/conf.d/redis.json

{
  "redis": {
    "host": "localhost",
    "port": 6379
  }
}

Configure Sensu API

sudo vi /etc/sensu/conf.d/api.json

{
 "api": {
    "host": "localhost",
    "port": 4567,
    "user": "<api-user>",
    "password": "<api-password>"
  }
}

Configure Sensu client

sudo vi /etc/sensu/conf.d/client.json

{
  "client": {
    "name": "<client-name>",
    "address": "<clien-ip>",
    "subscriptions": [ "all" ]
  }
}

Enable Sensu services

sudo chkconfig sensu-server on
sudo chkconfig sensu-client on
sudo chkconfig sensu-api on

Start Sensu services

sudo service sensu-server start
sudo service sensu-client start
sudo service sensu-api start

Install Sensu dashboard: Uchiwa

sudo yum install uchiwa

Configure Sensu dashboard: Uchiwa

sudo cp /etc/sensu/{uchiwa.json,uchiwa.json.old}
sudo vi /etc/sensu/uchiwa.json

{
    "sensu": [
        {
            "name": "Sensu",
            "host": "127.0.0.1",
            "ssl": false,
            "port": 4567,
            "user": "<api-user>",
            "pass": "<api-password>",
            "path": "",
            "timeout": 5000
        }
    ],
    "uchiwa": {
        "user": "<uchiwa-user>",
        "pass": "<uchiwa-password>",
        "port": 3000,
        "stats": 10,
        "refresh": 10000
    }
}

Enable and start Uchiwa

sudo chkconfig uchiwa on
sudo service uchiwa start

You can access Uchiwa in http://sensu-server-ip:3000

References: http://sensuapp.org/docs/0.16/guide http://www.rabbitmq.com/install-rpm.html