How to add per-request deadlines

livery_timeout is a middleware that bounds how long a handler may run. You need it when a slow handler would otherwise hang the client: instead of waiting forever, the client gets a 504.

Add it to the stack

Stack = [
    {livery_timeout, #{after_ms => 30_000}}   %% 30 second deadline
    %% ... handler
].

livery_timeout runs the rest of the pipeline in a monitored worker process. If the worker does not return within after_ms, the process is killed and 504 is emitted. Handler crashes are mapped to 500.

Set per-route deadlines

Stack the middleware multiple times with different keys, or mount separate stacks per route group:

FastApi    = [{livery_timeout, #{after_ms => 1_000}} | Common],
LongPolls  = [{livery_timeout, #{after_ms => 60_000}} | Common].

Notes

• Streaming request bodies: the deadline runs in a spawned, monitored worker, but body messages from the adapter target the original request process (livery_req_proc). Handlers that read body chunks via livery_body:read/2 will not see them under this middleware. Either place a body-buffering middleware in front of livery_timeout, or apply the middleware only to routes whose handlers do not stream input.
• Long-lived streams: SSE and chunked streaming handlers are open-ended by design. Do not place livery_timeout in front of them. If you need an idle timer for streams, implement it inside the producer with receive ... after Ms.

See also

• Reference: livery_request_id, livery_body_limit, livery_timeout, livery_access_log
• Reference: livery_resp