Server-Sent Events (SSE) Sink

The SSE sink exposes CDEvents as a real-time HTTP stream that any browser or HTTP client can subscribe to. Each sink creates one endpoint broadcasting all processed events.

Configuration

[sinks.events_stream]
enabled = true
type = "sse"
id = "events"

Endpoint accessible at: http://{host}:{port}/sse/{id}

Parameters

Parameter	Type	Default	Description
type	string	—	Must be "sse"
id	string	—	URL path identifier
enabled	boolean	true	Enable/disable this sink
headers	array	[]	Header validation rules for incoming connections

Authentication

Incoming connections are validated using the same header rules as webhook sources.

# Require a bearer token
[sinks.events_stream]
type = "sse"
id = "events"

[sinks.events_stream.headers]
"Authorization" = { type = "matches", pattern = "^Bearer [\\w-]+$" }

# Or a static API key from an environment variable
"X-API-Key" = { type = "secret", value = "SSE_API_KEY_ENV_VAR" }

→ Complete Header Validation Guide

Event Stream Format

Each CDEvent is sent as:

event: cdevent
id: {cdevent-id}
data: {cdevent-json}

Keep-alive messages are sent every 30 seconds:

: keep-alive

When a slow client's buffer (1000 messages) overflows, it receives:

event: error
data: lagged: {N} messages skipped

HTTP Response Codes

Status	Cause
200 OK	Valid connection
401 Unauthorized	Required header missing
403 Forbidden	Header value invalid
404 Not Found	Unknown SSE id

Examples

# Connect and stream events
curl -N -H "Accept: text/event-stream" \
     -H "Authorization: Bearer your-token" \
     http://localhost:8080/sse/events

# Multiple endpoints with different access levels
[sinks.public_stream]
enabled = true
type = "sse"
id = "public"

[sinks.admin_stream]
enabled = true
type = "sse"
id = "admin"

[sinks.admin_stream.headers]
"Authorization" = { type = "equals", value = "Bearer admin-secret", case_sensitive = true }

NOTE

The SSE sink requires the sink_sse feature flag at compile time. Verify with cdviz-collector --version.