Server Source code Package

Express

Turn-key HTTP event collection server with Express.js. Runs standalone or embeds inside an existing Express app, handles JSON POST events, pixel tracking via GET with a 1x1 transparent GIF, and configurable CORS.

Where this fits

The Express source is a server source in the walkerOS flow:

It receives events via HTTP (POST/GET) and forwards them to configured destinations.

Installation

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path setting renamed to paths

The path setting has been renamed to paths (array). The old path still works but is deprecated and will be removed in the next major version.

// Before (deprecated)
settings: { path: '/events' }

// After
settings: { paths: ['/events'] }

Integrated

Standalone server

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App-only mode

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Bundled

Add to your flow.json sources:

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Server sources require platform-specific handlers. For containerized deployments, see Docker.

See bundled mode setup | CLI reference

Configuration

This source uses the standard source config wrapper (consent, data, env, id, ...). For the shared fields see source configuration. Package-specific fields live under config.settings and are listed below.

Settings

Property	Type	Description	More
port	integer	HTTP server port to listen on. Use 0 for random available port. If not provided, server will not start (app only mode)
path	string	Deprecated: use paths instead
paths	Array<any>	Route paths to register. String shorthand registers GET+POST. RouteConfig allows per-route method control.
cors*	boolean | object	CORS configuration: false = disabled, true = allow all origins (default), object = custom configuration

* Required fields

Mapping

This package does not define custom rule-level settings. For the standard rule fields (consent, condition, data, batch, name, policy) see mapping.

Examples

pixel get

Event

Out

post event

Event

Out

HTTP methods

Method	Endpoint	Description
POST	/collect	JSON event ingestion
GET	/collect	Pixel tracking (returns 1x1 GIF)
OPTIONS	/collect	CORS preflight

Health checks

Health check endpoints (/health and /ready) are provided by the runner, not by individual sources. This means health checks work regardless of which source type you use.

Ingest metadata

Extract request metadata (IP, user agent, headers) and forward it through the pipeline to transformers and destinations.

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Available ingest paths

Path	Description
ip	Client IP address
headers.*	HTTP headers (user-agent, origin, referer, etc.)
protocol	Request protocol (http/https)
method	HTTP method (GET, POST, etc.)
hostname	Request hostname
url	Full request URL

Advanced mapping

Use walkerOS mapping features for complex extraction:

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Example request

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