Sinks

Sinks define where agent output goes after a run completes. They are most useful in daemon mode and flow pipelines, where agents run unattended and their results need to be routed somewhere — a webhook, a file, a custom function, or another agent.

Sinks are configured in the spec.sinks list.

Quick Example

spec:
  sinks:
    - type: webhook
      url: https://hooks.slack.com/services/T.../B.../xxx
      headers:
        Content-Type: application/json
    - type: file
      path: ./output/results.json
      format: json

Sink Types

Type	Description
`webhook`	HTTP POST to a URL
`file`	Write to a local file
`custom`	Call a Python function

Webhook

Sends a JSON payload to a URL via HTTP POST. Useful for Slack, Discord, PagerDuty, or any HTTP endpoint.

sinks:
  - type: webhook
    url: https://hooks.slack.com/services/T.../B.../xxx
    headers:
      Content-Type: application/json
      Authorization: Bearer ${WEBHOOK_TOKEN}
    timeout_seconds: 30
    retry_count: 3

Field	Type	Default	Description
`url`	`str`	(required)	Destination URL
`method`	`str`	`"POST"`	HTTP method
`headers`	`dict`	`{}`	HTTP headers (supports `${VAR}` substitution)
`timeout_seconds`	`int`	`30`	Request timeout
`retry_count`	`int`	`0`	Number of retry attempts on failure

Payload Format

The webhook POST body is a JSON object:

{
  "agent_name": "monitor-agent",
  "run_id": "a1b2c3d4e5f6",
  "trigger_type": "cron",
  "status": "success",
  "output": "All 3 services healthy. Response times: api=120ms, web=85ms, db=45ms.",
  "timestamp": "2025-01-15T09:00:05Z",
  "tokens_used": 1250,
  "duration_ms": 4200
}

File

Writes agent output to a local file. Supports JSON and plain text formats.

sinks:
  - type: file
    path: ./output/results.json
    format: json

Field	Type	Default	Description
`path`	`str`	(required)	Output file path
`format`	`str`	`"json"`	Output format: `"json"` or `"text"`

json — writes a JSON object (same schema as webhook payload)
text — writes the raw output string

Custom

Calls a Python function with the run result. Use this for custom integrations — database writes, email, message queues, or anything else.

sinks:
  - type: custom
    module: my_sinks
    function: send_to_database

Field	Type	Default	Description
`module`	`str`	(required)	Python module path (must be importable)
`function`	`str`	(required)	Function name to call

The function signature:

def send_to_database(result: dict) -> None:
    """Called by InitRunner after each agent run.

    Args:
        result: Run result dict (same schema as webhook payload).
    """
    # ... process result

Multiple Sinks

An agent can have multiple sinks. All sinks fire after each run completes:

spec:
  sinks:
    # Log to file
    - type: file
      path: ./logs/runs.json
      format: json
    # Notify Slack
    - type: webhook
      url: ${SLACK_WEBHOOK_URL}
    # Store in database
    - type: custom
      module: my_sinks
      function: store_result

Sinks with Daemon Mode

Sinks are most commonly used with triggers and daemon mode. When a trigger fires and an agent run completes, all configured sinks receive the result:

spec:
  triggers:
    - type: cron
      schedule: "0 */6 * * *"
      prompt: "Check system health and report status."
  sinks:
    - type: webhook
      url: ${SLACK_WEBHOOK_URL}
    - type: file
      path: ./logs/health-checks.json
      format: json

initrunner run role.yaml --daemon

Every 6 hours, the agent runs, and the output is sent to both Slack and the log file.

Sinks with Flow

In flow pipelines, agent chaining is handled by the flow orchestration layer. See the flow documentation for multi-agent pipeline examples.

On this page