Gaurav Bytes - bits and bytes of Programming

In the previous post, we have setup ELK stack and ran data analytics on application events and logs. In this post, we will discuss how you can watch real-time application events that are being persisted in the Elasticsearch index and raise alerts if condition for watcher is breached using SentiNL (Kibana plugin).

Few examples of alerting for application events (see previous posts) are:

• Same user logged in from different IP addresses.
• Different users logged in from same IP address.
• PermissionFailures in last 15 minutes.
• Particular kind of exception in last 15 minutes/ hour/ day.

Watching and alerting on Elasticsearch index in Kibana

There are many plugins available for watching and alerting on Elasticsearch index in Kibana e.g. X-Pack, SentiNL.

We will be using SentiNL for watching and alerting on Elasticsearch index.

Installing SentiNL

// Installing SentiNL plugin
/opt/kibana/bin/kibana-plugin --install sentinl -u https://github.com/sirensolutions/sentinl/releases/download/tag-4.6.4-4/sentinl.zip

Configuring SentiNL

SentiNL have wide range of actions that you can configure for watchers. You can send an email, integrate with Slack channel or pushapps, send payload to custom webhook. Open kibana.yml file and add below properties for SentiNL. For our example, we will only enable notification through email.

sentinl:
  es:
    host: 'localhost'
    port: 9200
  settings:
    email:
      active: true
      host: "smtp.gmail.com"
      user: "[EMAIL_ID]"
      password: "[PASSWORD]"
      port: 465
      domain: "gmail.com"
      ssl: true
      tls: false
      authentication: ['PLAIN', 'LOGIN', 'CRAM-MD5', 'XOAUTH2']
      timeout: 20000  # mail server connection timeout
      # cert:
      #   key: '/full/sys/path/to/key/file'
      #   cert: '/full/sys/path/to/cert/file'
      #   ca: '/full/sys/path/to/ca/file'
    slack:
      active: false
      username: 'username'
      hook: 'https://hooks.slack.com/services/'
      channel: '#channel'
    webhook:
      active: false
      host: 'localhost'
      port: 9200
      # use_https: false
      # path: ':/{{payload.watcher_id}}'
      # body: '{{payload.watcher_id}}{payload.hits.total}}'
      # method: POST
    report:
      active: false
      executable_path: '/usr/bin/chromium' # path to Chrome v59+ or Chromium v59+
      timeout: 5000
      # authentication:
      #   enabled: true
      #   mode:
      #     searchguard: false
      #     xpack: false
      #     basic: false
      #     custom: true
      #   custom:
      #     username_input_selector: '#username'
      #     password_input_selector: '#password'
      #     login_btn_selector: '#login-btn'
      # file:
      #   pdf:
      #     format: 'A4'
      #     landscape: true
      #   screenshot:
      #     width: 1280
      #     height: 900
    pushapps:
      active: false
      api_key: ''

That's it!!! Let's start Kibana to configure watcher and alerting in SentiNL.

Creating Watchers and alerting in Kibana

We will be configuring watcher for different users logged in from same IP address and will send e-Mail alerts.

• Open Kibana dashboard on your local machine (Url for Kibana on my local machine is http://localhost:5601).
• Click on SentiNL option in the left nav-pane. You will see a dashboard as below. Click on the New option to create a new watcher.
  
• Click on the Watcher link highlighted as below.
  
• Enter watcher name and schedule in the General tab.
  
• Click on Input tab and enter below mentioned query json in the body. You can also give a name to the query and save.

  {
    "search": {
      "request": {
        "index": [
          "app-events*"
        ],
        "body": {
          "query": {
            "bool": {
              "filter": [
                {
                  "range": {
                    "@timestamp": {
                      "gte": "now-30m"
                    }
                  }
                },
                {
                  "query_string": {
                    "default_field": "appEvent.eventType",
                    "query": "LOGIN_SUCCESS OR LOGIN_FAILURE"
                  }
                }
              ]
            }
          },
          "aggs": {
            "group_by_requestIP": {
              "terms": {
                "field": "appEvent.requestIP.keyword",
                "size": 5
              },
              "aggs": {
                "group_by_identifier": {
                  "terms": {
                    "field": "appEvent.identifier.keyword",
                    "size": 5
                  },
                  "aggs": {
                    "get_latest": {
                      "terms": {
                        "field": "@timestamp",
                        "size": 1,
                        "order": {
                          "_key": "desc"
                        }
                      }
                    }
                  }
                }
              }
            }
          }
        }
      }
    }
  }
  

• Click on Condition tab and enter below mentioned condition json in the body. You can also give a name to this condition and save.

  {
    "script": {
      "script": "var requestIPbuckets = payload.aggregations.group_by_requestIP.buckets; payload.collector = []; requestIPbuckets.filter(function(requestIP) { return requestIP.key; }).forEach(function(requestIP) { var requestIPKey = requestIP.key; var users = requestIP.group_by_identifier.buckets; if (users.length > 1) { users.filter(function(user) { return user.key; }).forEach(function(user) { payload.collector.push({ 'ip': requestIPKey, 'identifier': user.key, 'count': user.doc_count  }); }); }}); payload.collector.length > 0;"
    }
  }
  

• Click on Action tab and select email as an action for alerting. Give title, to, from, subject and add below mentioned content in the body of email.

  Found {{payload.collector.length}} Events
  {{#payload.collector}}
  {{#.}}
  ip : {{ip}}, identifier: {{identifier}}, count: {{count}}
  {{/.}}
  {{/payload.collector}}
  

• Save the watcher.

This watcher will run periodically based on the schedule that you have set and if the condition for breach is met, will send an email alert. The configured email looks like below.

This is how you can watch real-time changing data in Elasticsearch index and raise alerts based on the configured conditions.