Setting up a Sensu Slack Handler

I’ve been working on a Sensu install recently. I had some trouble getting the Slack handler working. The docs were a little off in terms of how to do this. But I can now say that it’s working. :)

First, you will need the sensu-plugins-slack plugin.

I have Sensu embedded, so I use that gem to install it. It’s already been installed below; I’m just showing the command.

# /opt/sensu/embedded/bin/gem install sensu-plugins-slack
You can use the embedded Ruby by setting EMBEDDED_RUBY=true in /etc/default/sensu
Successfully installed sensu-plugins-slack-1.0.0
Parsing documentation for sensu-plugins-slack-1.0.0
Installing ri documentation for sensu-plugins-slack-1.0.0
Done installing documentation for sensu-plugins-slack after 0 seconds
1 gem installed

Next, login to your slack account and create a webhook.

Now to configure it to be used.

# cat /etc/sensu/conf.d/slack_handler.json
  "handlers": {
    "slack": {
      "type": "pipe",
      "command": "handler-slack.rb",
      "severites": ["critical", "unknown"]
    "slack": {
      "webhook_url": "<your slack webhook url>",
      "template" : "",
      "channel": "#general"

I have also setup Slack to be a default handler.

# cat /etc/sensu/conf.d/default_handlers.json
  "handlers": {
    "default": {
      "type": "set",
      "handlers": [

Once that is setup and Sensu restarted, you should be able to get alerts into a Slack channel.

Happy Sensu Slacking!