Router

Server Source code Package

Routes events to different transformer chains based on ingest metadata. The router inspects context.ingest (set by the source) and branches to the first matching route.

Setup

Integrated
Bundled

Install the package:

Configure in your code:

Add to your flow.json:

See Bundled Mode setup → | CLI reference →

How it works

A server source (express, fetch) sets context.ingest with request metadata (path, method, headers, etc.)
The router evaluates routes in order — first match wins
On match, the event resets to {} and branches to the matched transformer chain
The downstream parser builds a proper event from context.ingest
If no route matches and there's no wildcard, the event passes through unchanged

Route configuration

Each route has a match expression and a next target:

Option	Type	Description
`match`	`MatchExpression \| '*'`	Condition to evaluate against ingest, or `'*'` wildcard
`next`	`string \| string[]`	Transformer chain(s) to branch to on match

Match operators

Operator	Description	Example
`eq`	Exact string match	`{ key: 'method', operator: 'eq', value: 'POST' }`
`prefix`	Starts with	`{ key: 'path', operator: 'prefix', value: '/api' }`
`suffix`	Ends with	`{ key: 'path', operator: 'suffix', value: '.json' }`
`contains`	Substring match	`{ key: 'path', operator: 'contains', value: 'collect' }`
`regex`	Regular expression	`{ key: 'path', operator: 'regex', value: '^/v\\d+/' }`
`gt`	Greater than (numeric)	`{ key: 'contentLength', operator: 'gt', value: '1000' }`
`lt`	Less than (numeric)	`{ key: 'contentLength', operator: 'lt', value: '5000' }`
`exists`	Key is present	`{ key: 'authorization', operator: 'exists', value: '' }`

Every condition supports negation with not: true:

Logical combinators

Combine conditions with and / or, nestable to any depth:

Deeply nested example

Examples

Multi-path server endpoint

Route different vendor payloads through dedicated parsers:

Branching to multiple chains

A route can target multiple chains at once:

Performance

Routes are compiled to closures at init time. Regular expressions are compiled once and reused on every request. Runtime evaluation is a simple loop with short-circuit logic for and/or combinators.

Next steps

Validator - Validate events after routing
Create your own - Build custom transformers

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Setup​

How it works​

Route configuration​

Match operators​

Logical combinators​

Examples​

Multi-path server endpoint​

Branching to multiple chains​

Performance​

Next steps​