Firehose (parlel emulator)

A zero-dependency, in-process fake of Amazon Data Firehose. Records are buffered in memory keyed by delivery stream.

Property	Value
Port	4725
Protocol	AWS JSON 1.1 (`X-Amz-Target: Firehose_20150804.<Op>`)
Healthcheck	`GET /_parlel/health`
Reset	`POST /_parlel/reset`

Default connection

AWS_REGION=us-east-1
AWS_ENDPOINT_URL=http://127.0.0.1:4725
AWS_ACCESS_KEY_ID=parlel
AWS_SECRET_ACCESS_KEY=parlel

Supported operations

CreateDeliveryStream, DescribeDeliveryStream, ListDeliveryStreams, DeleteDeliveryStream
PutRecord, PutRecordBatch

S3 (S3DestinationConfiguration / ExtendedS3DestinationConfiguration) and Elasticsearch/OpenSearch destination configs are accepted and echoed in DescribeDeliveryStream. Record Data is a base64 blob on the wire.

SDK example

import {
  FirehoseClient,
  CreateDeliveryStreamCommand,
  PutRecordCommand,
} from "@aws-sdk/client-firehose";

const fh = new FirehoseClient({
  region: "us-east-1",
  endpoint: "http://127.0.0.1:4725",
  credentials: { accessKeyId: "parlel", secretAccessKey: "parlel" },
});

await fh.send(new CreateDeliveryStreamCommand({
  DeliveryStreamName: "logs",
  S3DestinationConfiguration: { BucketARN: "arn:aws:s3:::my-bucket", RoleARN: "arn:aws:iam::000000000000:role/fh" },
}));
await fh.send(new PutRecordCommand({
  DeliveryStreamName: "logs",
  Record: { Data: Buffer.from("hello\n") },
}));

Access via MCP / preview URL

Reachable through the parlel pool MCP bridge and preview URL. No auth setup required.

Surface coverage

This emulator faithfully replicates the API surface most application code and agents exercise. Anything below the supported lines is either an intentional design choice for a fast, zero-cost local emulator (✓ By design) or a candidate for a future release (⟳ Roadmap) — never a silent inaccuracy.

Legend: ✅ fully supported · ◐ accepted (stored, not strictly enforced) · ✓ by design · ⟳ on the roadmap.

Area	Limitation
Delivery	Records are buffered in memory; nothing is flushed to S3/ES.
Transforms	Lambda transformation / format conversion is not applied.
Buffering	Buffering hints are stored but not enforced.
Encryption	`Encrypted` is always reported `false`.

Configuration — `test.env`

Copy these into your test.env (used by the bridge sidecar flow). Tokens are Parlel's seeded test credentials — any non-empty value is accepted by the emulator, so you rarely need to change them. Swap in real credentials only when pointing at the live service in prod.env.

AWS_ACCESS_KEY_ID=parlel
AWS_SECRET_ACCESS_KEY=parlel
AWS_REGION=us-east-1
AWS_ENDPOINT_URL=http://parlel-bridge:4725