Architecture

Loch Lambda Runtime is a Go module (github.com/loch-sh/lambda-runtime) with no dependency outside the standard library. Source: github.com/loch-sh/lambda-runtime.

Layout

Path	Role
cmd/loch-lambda-runtime	main: makes the process non-dumpable first, then dispatches the subcommand
internal/app	Wires the components into the subcommands (run, health), the connection limits and the credential reload
internal/config	Parses and validates the command line, the LOCH_RUNTIME_* settings, the function variables and the bootstrap environment
internal/engine	Runs the bootstrap and feeds it one invocation at a time: init, timeouts, outcomes, re-init, shutdown
internal/runtimeapi	The AWS Lambda™ Runtime API (2018-06-01) served to the bootstrap
internal/invokeapi	The Invoke API, health and metrics endpoints, browser filter, per-IP caps, error shapes
internal/auth	Bearer and SigV4 authentication, credential files and their checks
internal/queue	The bounded FIFO of waiting invocations
internal/process	Starts the bootstrap as a child process, PID 1 duties
internal/cgroup	Reads the container's own cgroup (memory limit, peak, OOM kills)
internal/logs	Relays the bootstrap output, writes the platform lines, keeps log tails
internal/metrics	Collects figures and writes the Prometheus format
internal/invokecli	The invoke subcommand
internal/ids, internal/netutil	Request and trace ids; networking helpers
internal/release	Tests of the release tooling (the Makefile)
integration/	Integration tests against the real AWS images, under Docker

Request flow

1. A caller sends POST /2015-03-31/functions/{name}/invocations to invokeapi.
2. invokeapi filters browsers, applies the caps, authenticates, reads the body and queues the invocation.
3. engine pops it when the bootstrap asks runtimeapi for the next invocation.
4. The bootstrap posts the response or the error; engine decides the outcome (error, timeout, OOM, exit) and answers the caller.
5. logs writes START, END and REPORT; metrics counts the outcome.

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"AWS" and "AWS Lambda" are trademarks of Amazon.com, Inc. or its affiliates. This project is not affiliated with or endorsed by Amazon. It implements the publicly documented AWS Lambda Runtime and Invoke APIs and contains no code from the AWS Lambda Runtime Interface Emulator.