event

Typed envelopes for the events Lambda delivers, with decoders for the common trigger sources. Lambda hands every trigger to the handler as a JSON document; these turn that document into a Gleam record.

Pair them with aws/lambda.start_json:

import aws/lambda
import aws/lambda/event

pub fn main() {
  lambda.start_json(
    event.sqs_decoder(),
    fn(sqs, _ctx) {
      list.each(sqs.records, fn(msg) { process(msg.body) })
      Ok(Nil)
    },
    fn(_) { json.null() },
  )
}

Each decoder models the fields handlers actually reach for and tolerates missing/null members so a slightly different payload shape never crashes decoding. Open-ended members are left for the caller to decode: an SQS body and an SNS message are raw Strings (often JSON you parse with your own decoder), and an EventBridge detail is decoded by a decoder you supply. Field shapes follow the AWS sample events documented under “Using AWS Lambda with ”.

Types

ApiGatewayProxyRequest

</>

An API Gateway REST API proxy-integration request (payload format 1.0). request_context is omitted; the fields here cover routing, headers, query, and body.

pub type ApiGatewayProxyRequest {
  ApiGatewayProxyRequest(
    resource: String,
    path: String,
    http_method: String,
    headers: dict.Dict(String, String),
    query_string_parameters: dict.Dict(String, String),
    path_parameters: dict.Dict(String, String),
    stage_variables: dict.Dict(String, String),
    body: option.Option(String),
    is_base64_encoded: Bool,
  )
}

Constructors

ApiGatewayProxyRequest(
  resource: String,
  path: String,
  http_method: String,
  headers: dict.Dict(String, String),
  query_string_parameters: dict.Dict(String, String),
  path_parameters: dict.Dict(String, String),
  stage_variables: dict.Dict(String, String),
  body: option.Option(String),
  is_base64_encoded: Bool,
)

ApiGatewayV2Request

</>

An API Gateway HTTP API request (payload format 2.0). method, path, and source_ip are flattened out of requestContext.http for convenience.

pub type ApiGatewayV2Request {
  ApiGatewayV2Request(
    version: String,
    route_key: String,
    raw_path: String,
    raw_query_string: String,
    cookies: List(String),
    headers: dict.Dict(String, String),
    query_string_parameters: dict.Dict(String, String),
    path_parameters: dict.Dict(String, String),
    stage_variables: dict.Dict(String, String),
    method: String,
    path: String,
    source_ip: String,
    body: option.Option(String),
    is_base64_encoded: Bool,
  )
}

Constructors

ApiGatewayV2Request(
  version: String,
  route_key: String,
  raw_path: String,
  raw_query_string: String,
  cookies: List(String),
  headers: dict.Dict(String, String),
  query_string_parameters: dict.Dict(String, String),
  path_parameters: dict.Dict(String, String),
  stage_variables: dict.Dict(String, String),
  method: String,
  path: String,
  source_ip: String,
  body: option.Option(String),
  is_base64_encoded: Bool,
)

EventBridgeEvent

</>

An EventBridge (CloudWatch Events) event. The detail payload is service-specific, so this type is generic over it: supply a decoder to eventbridge_decoder. Use decode.dynamic (or gleam/json’s document handling) if you want to keep it untyped.

pub type EventBridgeEvent(detail) {
  EventBridgeEvent(
    id: String,
    version: String,
    detail_type: String,
    source: String,
    account: String,
    time: String,
    region: String,
    resources: List(String),
    detail: detail,
  )
}

Constructors

EventBridgeEvent(
  id: String,
  version: String,
  detail_type: String,
  source: String,
  account: String,
  time: String,
  region: String,
  resources: List(String),
  detail: detail,
)

S3Event

</>

An aws:s3 event notification: a batch of object-level records.

pub type S3Event {
  S3Event(records: List(S3Record))
}

Constructors

```
S3Event(records: List(S3Record))
```

S3Record

</>

A single S3 notification record. The bucket and object fields are flattened out of the nested s3 member. object_key is URL-encoded exactly as S3 delivers it (spaces become +).

pub type S3Record {
  S3Record(
    aws_region: String,
    event_name: String,
    event_time: String,
    event_source: String,
    bucket_name: String,
    bucket_arn: String,
    object_key: String,
    object_size: option.Option(Int),
    object_etag: option.Option(String),
    object_sequencer: option.Option(String),
  )
}

Constructors

S3Record(
  aws_region: String,
  event_name: String,
  event_time: String,
  event_source: String,
  bucket_name: String,
  bucket_arn: String,
  object_key: String,
  object_size: option.Option(Int),
  object_etag: option.Option(String),
  object_sequencer: option.Option(String),
)

SnsEvent

</>

An aws:sns event: a batch of one or more notifications.

pub type SnsEvent {
  SnsEvent(records: List(SnsRecord))
}

Constructors

```
SnsEvent(records: List(SnsRecord))
```

SnsMessage

</>

A published SNS message. message is the raw payload — parse it with your own decoder if it carries JSON.

pub type SnsMessage {
  SnsMessage(
    message_id: String,
    topic_arn: String,
    subject: option.Option(String),
    message: String,
    timestamp: String,
    message_type: String,
  )
}

Constructors

SnsMessage(
  message_id: String,
  topic_arn: String,
  subject: option.Option(String),
  message: String,
  timestamp: String,
  message_type: String,
)

SnsRecord

</>

A single SNS record wrapping the published message.

pub type SnsRecord {
  SnsRecord(
    event_source: String,
    event_subscription_arn: String,
    sns: SnsMessage,
  )
}

Constructors

SnsRecord(
  event_source: String,
  event_subscription_arn: String,
  sns: SnsMessage,
)

SqsEvent

</>

An aws:sqs event: a batch of one or more messages.

pub type SqsEvent {
  SqsEvent(records: List(SqsMessage))
}

Constructors

```
SqsEvent(records: List(SqsMessage))
```

SqsMessage

</>

A single SQS message. body is the raw message body — parse it with your own decoder if it carries JSON.

pub type SqsMessage {
  SqsMessage(
    message_id: String,
    receipt_handle: String,
    body: String,
    attributes: dict.Dict(String, String),
    message_attributes: dict.Dict(String, SqsMessageAttribute),
    md5_of_body: String,
    event_source: String,
    event_source_arn: String,
    aws_region: String,
  )
}

Constructors

SqsMessage(
  message_id: String,
  receipt_handle: String,
  body: String,
  attributes: dict.Dict(String, String),
  message_attributes: dict.Dict(String, SqsMessageAttribute),
  md5_of_body: String,
  event_source: String,
  event_source_arn: String,
  aws_region: String,
)

SqsMessageAttribute

</>

A user-supplied SQS message attribute. Binary attributes carry data_type "Binary" and no string_value.

pub type SqsMessageAttribute {
  SqsMessageAttribute(
    data_type: String,
    string_value: option.Option(String),
  )
}

Constructors

SqsMessageAttribute(
  data_type: String,
  string_value: option.Option(String),
)

Values

api_gateway_decoder

</>

pub fn api_gateway_decoder() -> decode.Decoder(
  ApiGatewayProxyRequest,
)

Decoder for the API Gateway REST proxy request (payload format 1.0).

api_gateway_v2_decoder

</>

pub fn api_gateway_v2_decoder() -> decode.Decoder(
  ApiGatewayV2Request,
)

Decoder for the API Gateway HTTP API request (payload format 2.0).

eventbridge_decoder

</>

pub fn eventbridge_decoder(
  detail_decoder: decode.Decoder(detail),
) -> decode.Decoder(EventBridgeEvent(detail))

Decoder for an EventBridge event, decoding detail with detail_decoder.

s3_decoder

</>

pub fn s3_decoder() -> decode.Decoder(S3Event)

Decoder for the S3 event-notification envelope.

sns_decoder

</>

pub fn sns_decoder() -> decode.Decoder(SnsEvent)

Decoder for the SNS event envelope.

sqs_decoder

</>

pub fn sqs_decoder() -> decode.Decoder(SqsEvent)

Decoder for the SQS event envelope.