Ansible Role: Sensu

Installs Sensu (either as a server or as a client) on servers.

At present, this role does not support RabbitMQ TLS/SSL communciation. This is a planned addition.

Supported Platforms

Currently this role only supports Debian-family hosts. RedHat-family hosts are a planned addition.

Requirements

In general, Sensu has two dependencies: RabbitMQ and Redis. This role doesn't assume that these are running on the same machine. Please have both installed and accessible and running.

Configuration (as a Client)

To install Sensu as a client, simply override the variable sensu_rabbitmq:

sensu_rabbitmq:
  host: rmq01.mydomain.local
  port: 5672 # default RMQ port
  username: sensu_user
  password: sensu_password

If you'd like the client to identify itself as something other than its hostname (not fully qualified), override sensu_client_name. If you want custom identifiers, it's recommended that you do this in your inventory file:

[webservers]
crimson.mydomain.local sensu_client_name=web01

If you'd like to customize the IP address reported by the client, you can similarly override sensu_client_ip.

Advanced: Copying plugins

If you'd like this role to auto-magically copy over your plugins, override the sensu_plugins variable:

sensu_plugins:
  - files/sensu/plugins/check-procs.rb
  - files/sensu/plugins/cpu-metrics.rb
  # etc...

Note: Path handling here is handled by Ansible. This typically means that it will search for files first in this role's directory, then in your present working directory. Test this before a full-scale deployment.

This files will end up in /etc/sensu/plugins/, but that's entirely configurable. You can override sensu_plugins_directory to instruct the role to place them elsewhere.

Configuration (as a Server)

Configuration as a server is almost the same as configuring as a client, but you need to inform the role that you wish to configure and run the API and Server daemons.

First, ensure that you have the correct services details defined:

sensu_rabbitmq:
  host: rmq01.mydomain.local
  port: 5672 # default RMQ port
  username: sensu_user
  password: sensu_password

sensu_redis:
  host: rds01.mydomain.local
  port: 6379 # default Redis port

sensu_api:
  host: localhost
  port: 4567
  username: admin
  password: unicorns

Next, override sensu_configs to let the Role know that you'd like it to also template the configuration files for the API and Redis (these are not required on client nodes):

sensu_configs:
  - client
  - rabbitmq
  - api
  - redis

This role will template those files, using the variables we defined above.

Finally, we need to let the role which services to start. Override sensu_services:

sensu_services:
  - sensu-server
  - sensu-api
  - sensu-client

And you'll have a minimal server installation. Congrats!

Advanced: Copying extensions

Much like copying plugins to the host (in fact, you should do this on server nodes too), this role will copy extensions over for you. Simply override sensu_extensions:

sensu_extensions:
  - files/sensu/extensions/flapjack.rb
  - files/sensu/extensions/graphite.rb
  # ...

This file will end up in /etc/sensu/extensions/. You can modify this by overriding sensu_extensions_directory, but, be warned, Sensu only automatically loads extensions from that path.

Advanced: Generating checks

This role will automatically generate checks for you! Check definitions only need to be present on the server nodes, so take care to define the following variables for those servers.

To add checks, override the sensu_checks variable:

sensu_checks:
  - name: check_cron
    command: "{{ sensu_plugins_directory }}/check-procs.rb -d cron -C 1"

This is the simplest possible check. You only need to specify a name and a command, the rest will be taken care of.

Parameter	Req.	Type	Default	Description
name	✓	string	n/a	The unique name of the check
command	✓	string	n/a	The command to be executed for the check
subscribers	✗	list	{{sensu_default_subscribers}}	An array of subscribers
handlers	✗	list	{{sensu_default_handlers}}	An array of handlers
interval	✗	int	{{sensu_default_interval}}	The interval (in seconds) at which this check should be performed
type	✗	string	n/a	The type of the check. Add metric for metric checks.

So, an example of a more thorough check might be:

- name: cpu_metrics
  command: "{{ sensu_plugins_directory }}/cpu-metrics.rb"
  type: metric
  subscribers:
    - webservers
    - databases
  handlers:
    - default
    - graphite
  interval: 15

Example Playbook

sensu-clients.yml

---
- hosts: all
  vars_files:
    - vars/sensu-clients.yml
  roles:
    - clarkf.sensu

vars/sensu-clients.yml

---
sensu_rabbitmq:
  host: rmq01.mydomain.local
  port: 5672 # default RMQ port
  username: sensu_user
  password: sensu_password

sensu_plugins:
  - files/check-proc.rb

sensu-servers.yml

---
- hosts: monitors
  vars_files:
    - vars/sensu-clients.yml
    - vars/sensu-servers.yml
  roles:
    - clarkf.sensu

vars/sensu-servers.yml

---
sensu_redis:
  host: rds01.mydomain.local
  port: 6379 # default Redis port

sensu_api:
  host: localhost
  port: 4567
  username: admin
  password: unicorns

sensu_configs:
  - client
  - rabbitmq
  - api
  - redis

sensu_services:
  - sensu-server
  - sensu-api
  - sensu-client

sensu_extensions:
  - files/sensu/extensions/flapjack.rb
  - files/sensu/extensions/graphite.rb

sensu_checks:
  - name: check_cron
    command: "{{ sensu_plugins_directory }}/check-procs.rb -d cron -C 1"
  - name: check_ntp
    command: "{{ sensu_plugins_directory }}/check-procs.rb -d ntp -C 1"

License

MIT. See LICENSE for details.

TODO

• Support for SSL/TLS RabbitMQ communication
• Support for RedHat-family operating systems (well... at least CentOS6).

Contributing

See contributing.md.