Mayfly.LocalRuntime (Mayfly v1.0.0-rc.1)

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A small Lambda Runtime API emulator for local development and tests.

It speaks enough of the Runtime API for Mayfly (and any other custom runtime) to run against it: GET /next blocks until an event is queued, /response and /error deliver the outcome to whoever invoked, including streamed responses and error trailers.

{:ok, rt} = Mayfly.LocalRuntime.start_link()
{:ok, _} = Mayfly.start_link(handler: "MyApp.Handler", runtime_api: Mayfly.LocalRuntime.address(rt))

Mayfly.LocalRuntime.invoke(rt, %{"name" => "world"})
#=> {:ok, %{status: 200, body: ~s({"hello":"world"}), headers: [...]}}

Mayfly.LocalRuntime.invoke(rt, %{"bad" => true})
#=> {:error, %{"errorType" => "KeyError", "errorMessage" => ..., "stackTrace" => [...]}}

Init errors are exposed through init_error/1. The emulator is single-tenant and does not enforce timeouts; it is a development aid, not a faithful Lambda simulation. For that, use aws-lambda-rie.

Summary

Types

invoke_result()

Functions

address(rt)

host:port string suitable for AWS_LAMBDA_RUNTIME_API.

child_spec(init_arg)

Returns a specification to start this module under a supervisor.

init_error(rt)

The payload posted to /runtime/init/error, if any.

invoke(rt, event, opts \\ [])

Queues event (any JSON-encodable term or a raw binary), waits for the runtime to process it and returns the outcome.

start_link(opts \\ [])

Starts the emulator on an ephemeral port (or :port).

Types

invoke_result()

@type invoke_result() ::
  {:ok,
   %{
     status: 200,
     headers: [{String.t(), String.t()}],
     body: binary(),
     trailers: map()
   }}
  | {:error, map()}

Functions

address(rt)

@spec address(GenServer.server()) :: String.t()

host:port string suitable for AWS_LAMBDA_RUNTIME_API.

child_spec(init_arg)

Returns a specification to start this module under a supervisor.

See Supervisor.

init_error(rt)

@spec init_error(GenServer.server()) :: map() | nil

The payload posted to /runtime/init/error, if any.

invoke(rt, event, opts \\ [])

@spec invoke(GenServer.server(), term(), keyword()) :: invoke_result()

Queues event (any JSON-encodable term or a raw binary), waits for the runtime to process it and returns the outcome.

start_link(opts \\ [])

Starts the emulator on an ephemeral port (or :port).