aws-lambda.ml

OCaml libraries for AWS Lambda custom runtimes.

• aws-lambda: the Runtime API loop. HTTP is an OCaml 5 effect (Transport.Call); depends on the stdlib only.
• aws-lambda-eio: a transport backed by cohttp-eio.

Install

opam pin add aws-lambda https://github.com/lmdexpr/aws-lambda.ml.git
opam pin add aws-lambda-eio https://github.com/lmdexpr/aws-lambda.ml.git

Usage

let () =
  Eio_main.run @@ fun env ->
  let client = Cohttp_eio.Client.make ~https:None env#net in
  let endpoint = Option.get (Aws_lambda_eio.endpoint_from_env ()) in
  let fatal =
    Aws_lambda_eio.run ~client ~endpoint @@ fun invocation ->
    Ok (Printf.sprintf {|{"echo":%s}|} invocation.payload)
  in
  prerr_endline (Aws_lambda.fatal_to_string fatal);
  exit 1

A handler returns Ok payload or Error (Aws_lambda.Error.v ~error_type msg); exceptions are reported as errors. run returns when the loop cannot continue. Aws_lambda.Context.of_env Sys.getenv_opt reads the function configuration; Aws_lambda.report_init_error reports start-up failures.

With another HTTP client, handle the effect yourself:

try Aws_lambda.run handler
with effect Aws_lambda.Transport.Call request, k ->
  Effect.Deep.continue k (send request)

Ship the binary as bootstrap (zip, provided.al2023) or as a container image.

License

MIT