Configure HTTP Reaction

Send webhooks and HTTP requests when query results change

  4 minute read  

The HTTP Reaction Reaction A component that receives query result changes and takes action on them. Learn more sends HTTP requests when query results change Result Change Event A notification from a Continuous Query describing changes to its result set. Learn more . Use it for webhooks, API integrations, and triggering external systems.

Basic Configuration

reactions:
  - kind: http
    id: webhook
    queries: [my-query]
    baseUrl: https://api.example.com
    routes:
      my-query:
        added:
          url: /events
          method: POST

Configuration Reference

Field Type Default Description
kind string Required Must be http
id string Required Unique reaction identifier
queries array Required Query IDs to subscribe to
autoStart boolean true Start reaction automatically
baseUrl string http://localhost Base URL for requests
token string None Bearer token for authorization
timeoutMs integer 5000 Request timeout in milliseconds
routes object {} Per-query endpoint configurations

Route Configuration

Each query can have routes for different change types:

Change Type When Triggered Data Available
added New item in results {{after}}
updated Item changed {{before}}, {{after}}
deleted Item removed {{before}}

Route Options

Field Type Required Description
url string Yes Path to append to baseUrl (or an absolute http(s)://... URL)
method string Yes HTTP method (GET, POST, PUT, DELETE, PATCH)
body string No Request body (supports templates). If empty, the plugin sends the raw JSON data for that change.
headers object No Custom HTTP headers (values also support templates)

Handlebars Templates

URLs and bodies support Handlebars templating:

routes:
  my-query:
    added:
      url: /orders/{{after.id}}
      method: POST
      body: |
        {
          "order_id": "{{after.id}}",
          "total": {{after.total}},
          "customer": "{{after.customer_name}}"
        }

Template Variables

Variable Description
{{after}} Full after object
{{after.property}} Specific property value
{{before}} Full before object (update/delete)
{{before.property}} Previous property value
{{json after}} JSON-serialized object

Authentication

Bearer Token

reactions:
  - kind: http
    id: api-webhook
    queries: [events]
    baseUrl: https://api.example.com
    token: ${API_TOKEN}

Adds header: Authorization: Bearer <token>

Custom Headers

reactions:
  - kind: http
    id: custom-auth
    queries: [events]
    baseUrl: https://api.example.com
    routes:
      events:
        added:
          url: /webhook
          method: POST
          headers:
            X-API-Key: ${API_KEY}
            X-Custom-Header: custom-value
            Content-Type: application/json

Examples

Simple Webhook

reactions:
  - kind: http
    id: simple-webhook
    queries: [orders]
    baseUrl: https://hooks.example.com
    routes:
      orders:
        added:
          url: /new-order
          method: POST
          body: '{{json after}}'
          headers:
            Content-Type: application/json

GitHub Integration

Create GitHub issues on alerts:

reactions:
  - kind: http
    id: github-issues
    queries: [critical-alerts]
    baseUrl: https://api.github.com
    token: ${GITHUB_TOKEN}
    routes:
      critical-alerts:
        added:
          url: /repos/{{after.repo}}/issues
          method: POST
          body: |
            {
              "title": "Alert: {{after.type}}",
              "body": "{{after.message}}\n\nSeverity: {{after.severity}}"
            }
          headers:
            Accept: application/vnd.github+json
            X-GitHub-Api-Version: "2022-11-28"

Slack Notification

reactions:
  - kind: http
    id: slack-alerts
    queries: [important-events]
    baseUrl: https://hooks.slack.com
    routes:
      important-events:
        added:
          url: /services/XXX/YYY/ZZZ
          method: POST
          body: |
            {
              "text": "New event: {{after.title}}",
              "blocks": [
                {
                  "type": "section",
                  "text": {
                    "type": "mrkdwn",
                    "text": "*{{after.title}}*\n{{after.description}}"
                  }
                }
              ]
            }
          headers:
            Content-Type: application/json

RESTful API Updates

reactions:
  - kind: http
    id: sync-api
    queries: [products]
    baseUrl: https://inventory.example.com/api
    token: ${API_TOKEN}
    timeoutMs: 10000
    routes:
      products:
        added:
          url: /products
          method: POST
          body: '{{json after}}'
          headers:
            Content-Type: application/json
        updated:
          url: /products/{{after.id}}
          method: PUT
          body: '{{json after}}'
          headers:
            Content-Type: application/json
        deleted:
          url: /products/{{before.id}}
          method: DELETE

Multi-Query Webhook

reactions:
  - kind: http
    id: event-hub
    queries: [orders, inventory, customers]
    baseUrl: https://events.example.com
    token: ${EVENT_HUB_TOKEN}
    routes:
      orders:
        added:
          url: /events/order-created
          method: POST
          body: '{"order": {{json after}}}'
        updated:
          url: /events/order-updated
          method: POST
          body: '{"order": {{json after}}, "previous": {{json before}}}'
      inventory:
        updated:
          url: /events/stock-changed
          method: POST
          body: '{"product": "{{after.sku}}", "quantity": {{after.quantity}}}'
      customers:
        added:
          url: /events/customer-registered
          method: POST
          body: '{"customer": {{json after}}}'

Timeout Configuration

reactions:
  - kind: http
    id: slow-api
    queries: [events]
    baseUrl: https://slow-api.example.com
    timeoutMs: 30000

Error Handling

HTTP reactions log errors but continue processing. Monitor logs for:

  • Connection timeouts
  • HTTP error responses (4xx, 5xx)
  • Invalid response formats

Enable debug logging for troubleshooting:

logLevel: debug

Testing

Using webhook.site

Test webhooks without a real endpoint:

  1. Go to https://webhook.site
  2. Copy your unique URL
  3. Configure the reaction:
reactions:
  - kind: http
    id: test-webhook
    queries: [my-query]
    baseUrl: https://webhook.site
    routes:
      my-query:
        added:
          url: /your-unique-id
          method: POST
          body: '{{json after}}'

Local Testing

Use a local HTTP server:

# Python
python -m http.server 9999

# Node.js
npx http-server -p 9999

reactions:
  - kind: http
    id: local-test
    queries: [my-query]
    baseUrl: http://localhost:9999
    routes:
      my-query:
        added:
          url: /test
          method: POST

Complete Example

host: 0.0.0.0
port: 8080
logLevel: info

sources:
  - kind: postgres
    id: orders-db
    host: ${DB_HOST}
    database: ecommerce
    user: ${DB_USER}
    password: ${DB_PASSWORD}
    tables:
      - public.orders

queries:
  - id: high-value-orders
    query: |
      MATCH (o:orders)
      WHERE o.total > 500
      RETURN o.id, o.customer_id, o.total, o.status
    sources:
      - sourceId: orders-db

reactions:
  - kind: http
    id: order-notifications
    queries: [high-value-orders]
    baseUrl: ${WEBHOOK_URL}
    token: ${WEBHOOK_TOKEN}
    timeoutMs: 10000
    routes:
      high-value-orders:
        added:
          url: /orders/high-value
          method: POST
          body: |
            {
              "event": "high_value_order",
              "order_id": "{{after.id}}",
              "customer_id": "{{after.customer_id}}",
              "total": {{after.total}}
            }
          headers:
            Content-Type: application/json
        updated:
          url: /orders/{{after.id}}/status
          method: PUT
          body: |
            {
              "status": "{{after.status}}",
              "previous_status": "{{before.status}}"
            }
          headers:
            Content-Type: application/json

Documentation resources

HTTP Reaction README

Routing, templates, and payload behavior

drasi-reaction-http on crates.io

Package info and release history

Next steps


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