MongoDB Connection Spike and Exhaustion Guard

id: mongodb-connection-spike-exhaustion-guard
namespace: company.database

description: Audits MongoDB replica set active connections against configured
  capacity, alerting DBAs before connection exhaustion rejects client
  applications.

concurrency:
  limit: 1

inputs:
  - id: mongodb_connection_uri
    type: STRING
    defaults: "mongodb://mongodb-primary.internal:27017"
    description: MongoDB connection string pointing to the primary replica set node.

  - id: max_connection_utilization_percent_warning
    type: FLOAT
    defaults: 80.0
    description: Connection utilization percentage threshold above which a
      saturation warning is triggered.

  - id: slack_channel
    type: STRING
    defaults: "#mongodb-dba-alerts"
    description: Slack channel destination for MongoDB connection capacity alerts.

tasks:
  - id: audit_mongodb_connections
    type: io.kestra.plugin.scripts.python.Script
    containerImage: python:3.11-slim
    beforeCommands:
      - pip install pymongo
    env:
      MONGO_URI: "{{ inputs.mongodb_connection_uri }}"
      MONGO_USER: "{{ secret('MONGODB_USER') }}"
      MONGO_PASSWORD: "{{ secret('MONGODB_PASSWORD') }}"
      UTIL_LIMIT: "{{ inputs.max_connection_utilization_percent_warning }}"
    script: |
      import os
      import json
      from pymongo import MongoClient
      from kestra import Kestra

      uri = os.getenv('MONGO_URI')
      user = os.getenv('MONGODB_USER')
      password = os.getenv('MONGODB_PASSWORD')
      util_limit = float(os.getenv('UTIL_LIMIT', 80.0))

      client = MongoClient(uri, username=user, password=password, serverSelectionTimeoutMS=10000)
      server_status = client.admin.command('serverStatus')
      client.close()

      connections_data = server_status.get('connections', {})
      current_conn = connections_data.get('current', 0)
      available_conn = connections_data.get('available', 1)
      total_capacity = current_conn + available_conn

      utilization_percent = (current_conn / total_capacity) * 100.0 if total_capacity > 0 else 0.0
      has_saturation = utilization_percent >= util_limit

      Kestra.outputs({
          'current_connections': current_conn,
          'available_connections': available_conn,
          'total_capacity': total_capacity,
          'utilization_percent': round(utilization_percent, 2),
          'has_connection_saturation': has_saturation
      })

      report = {
          'server': uri,
          'current_connections': current_conn,
          'available_connections': available_conn,
          'total_capacity': total_capacity,
          'utilization_percent': round(utilization_percent, 2),
          'threshold_percent': util_limit,
          'has_saturation': has_saturation
      }

      with open('mongodb_connections_report.json', 'w') as f:
          json.dump(report, f, indent=2)

    outputFiles:
      - mongodb_connections_report.json

  - id: check_connection_saturation
    type: io.kestra.plugin.core.flow.If
    condition: "{{ outputs.audit_mongodb_connections.vars.has_connection_saturation }}"
    then:
      - id: notify_slack_dba
        type: io.kestra.plugin.slack.notifications.SlackIncomingWebhook
        url: "{{ secret('SLACK_WEBHOOK_URL') }}"
        payload: |
          {
            "channel": "{{ inputs.slack_channel }}",
            "text": "MongoDB Connection Saturation Alert: Active connections reached {{ outputs.audit_mongodb_connections.vars.utilization_percent }}% of total cluster capacity (Threshold: {{ inputs.max_connection_utilization_percent_warning }}%).\n• Active Connections: {{ outputs.audit_mongodb_connections.vars.current_connections }} / {{ outputs.audit_mongodb_connections.vars.total_capacity }}\n• Available Slots Remaining: {{ outputs.audit_mongodb_connections.vars.available_connections }}\n• Remediation: Inspect application client connection pool `maxPoolSize` settings and check for dangling unclosed cursors."
          }
    else:
      - id: log_connections_nominal
        type: io.kestra.plugin.core.log.Log
        message: "MongoDB connection capacity is healthy. Utilization is {{
          outputs.audit_mongodb_connections.vars.utilization_percent }}% ({{
          outputs.audit_mongodb_connections.vars.current_connections }} active
          of {{ outputs.audit_mongodb_connections.vars.total_capacity }}
          slots)."

  - id: export_connection_manifest
    type: io.kestra.plugin.core.execution.Labels
    labels:
      active_connections: "{{
        outputs.audit_mongodb_connections.vars.current_connections | string }}"
      utilization_ratio: "{{
        outputs.audit_mongodb_connections.vars.utilization_percent | string }}"
      capacity_status: "{{
        outputs.audit_mongodb_connections.vars.has_connection_saturation ?
        'SATURATION_RISK' : 'HEALTHY' }}"

triggers:
  - id: periodic_connection_probe
    type: io.kestra.plugin.core.trigger.Schedule
    cron: "*/10 * * * *"