Multipart split — multipart-split

# Multipart split with object payload: one upload fans out so the file is
# stored as raw bytes in S3 and the form fields land in RabbitMQ.
#
# Requires UPLOAD_SOURCE_SECRET, ARCHIVE_BUCKET, and RABBITMQ_URL.
#
# How it works:
#   1. envelope body_format: multipart parses the request into {fields, files}.
#   2. Fan-out from `env` clones the envelope onto two branches.
#   3. The S3 branch reshapes body to the single file object and publishes
#      with payload: object — S3 PutObject writes decoded bytes with the
#      vendor Content-Type and a filename suffix on the key.
#   4. The info branch publishes fields + file metadata (no bytes) as the
#      normal JSON envelope to RabbitMQ.
#
# Object payload body contract: {content: "<base64>", filename?, content_type?}.
# Supported destinations: s3, redis_kv. Default payload (envelope) still writes
# the JSON Message for every destination type.
# The 4 MiB code-node limits account for base64 expansion of the 2 MiB file cap.
server:
  addr: ":8080"
  max_body_bytes: 3145728

destinations:
  archive:
    type: s3
    s3:
      region: "us-east-1"
      bucket: "${ARCHIVE_BUCKET}"
      create: true
  events:
    type: rabbitmq
    rabbitmq:
      url: "${RABBITMQ_URL}"
      exchange: "hookway.uploads"
      exchange_type: "direct"
      durable: true
      publish_timeout: "5s"
      declare_queues: true

flows:
  upload_split:
    nodes:
      - {id: in, type: http_trigger, description: "Vendor posts multipart/form-data (fields + file).", path: /webhooks/upload-split, methods: [POST]}
      - {id: body, type: read_body, description: "Buffers the whole request so HMAC can cover file bytes.", max_bytes: 3145728}
      - {id: auth, type: auth, description: "Verifies HMAC over the raw multipart bytes before parsing.", scheme: hmac_sha256_hex, secret: "${UPLOAD_SOURCE_SECRET}", signature_header: X-Hub-Signature-256}
      - id: env
        type: envelope
        description: "Parses parts into {fields, files}. include_content keeps file bytes for the S3 branch."
        body_format: multipart
        multipart:
          max_parts: 2
          max_part_bytes: 2097152
          include_content: true
      - id: for_s3
        type: code
        description: "S3 object payload needs the file object itself as body (content + metadata)."
        timeout: 50ms
        max_input_bytes: 4194304
        max_output_bytes: 4194304
        script: |
          const files = (input.body && input.body.files) || {};
          const doc = files.document;
          if (!doc) {
            throw new Error('missing files.document');
          }
          return {body: doc, vars: input.vars || {}};
      - id: for_info
        type: code
        description: "Info branch body: form fields + file metadata, no base64 payload."
        timeout: 50ms
        max_input_bytes: 4194304
        script: |
          const files = (input.body && input.body.files) || {};
          const meta = {};
          for (const [name, file] of Object.entries(files)) {
            meta[name] = {
              filename: file.filename || '',
              content_type: file.content_type || '',
              size: file.size || 0
            };
          }
          return {
            body: {
              fields: (input.body && input.body.fields) || {},
              files: meta
            },
            vars: input.vars || {}
          };
      - id: out_s3
        type: publish
        description: "Stores decoded file bytes under uploads/…/<id>-<filename> in S3."
        destination: archive
        target: uploads
        payload: object
      - {id: out_info, type: publish, description: "Publishes fields + file metadata to the events queue.", destination: events, target: uploads-meta, create: true}
    edges:
      - in>body
      - body>auth
      - auth>env
      - env>for_s3
      - env>for_info
      - for_s3>out_s3
      - for_info>out_info