Architecture

Overview

backend-crons is a Serverless Framework v3 service (abstract-play-backend-crons) deployed to AWS us-east-1. All functions are Node.js 20 Lambdas triggered by EventBridge cron rules (prod only).

There is no API Gateway — these are batch and maintenance jobs only.

Lambda functions

Defined in serverless.yml:

Function	Schedule (UTC, prod)	Role
`dumpdb`	Sun 00:00	Export prod DynamoDB to S3
`records`	Sun 03:00	Build game records from dump
`records-ttm`	Sun 03:00	Per-player time-to-move arrays
`records-move-times`	Sun 03:00	Move activity histograms (180 days)
`tournament-data`	Sun 03:00	Tournament summaries from dump
`records-manifest`	Sun 04:00 and 07:00	S3 listing + CloudFront invalidation
`summarize`	Daily 06:00	Site analytics from `ALL.json`
`starttournaments`	Daily 10:00 and 22:00	Start/cancel tournaments, create games
`standingchallenges`	Daily 00:00 and 12:00	Process preset standing challenges

See Records pipeline and Functions reference for details.

Gameslib Lambda layer

Functions that call @abstractplay/gameslib attach the abstractplayGameslib layer, built by scripts/build-layers.cjs before packaging:

Bundles @abstractplay/gameslib and @abstractplay/recranks into .serverless/layers/abstractplay-gameslib
Strips @abstractplay/renderer (transitive dep, not needed at runtime)
Prunes docs, tests, and locales from the layer to stay under Lambda size limits

esbuild marks @abstractplay/gameslib and @abstractplay/recranks as external so they resolve from the layer at runtime, not from the function bundle.

Data flow

flowchart LR
    ddb[(DynamoDB abstract-play-prod)] --> dumpdb
    dumpdb --> s3dump[(S3 abstractplay-db-dump)]
    s3dump --> records
    records --> s3rec[(S3 records.abstractplay.com)]
    s3rec --> summarize
    summarize --> s3rec
    ddb --> live[Live crons]
    live --> ddb
    s3rec --> cf[CloudFront invalidation]

IAM permissions

The service role grants:

DynamoDB — query/scan/get/put/update/delete, batch write, point-in-time export
S3 — list/get on abstractplay-db-dump; put on records.abstractplay.com and dump bucket
SES — send email (tournament notifications)
CloudFront — create invalidation on the records distribution

Environment

Variable	Source	Purpose
`ABSTRACT_PLAY_TABLE`	`serverless.yml`	`abstract-play-{stage}` — used by `summarize` (geo stats) and live crons

Dependencies

Package	Used by	Purpose
`@abstractplay/gameslib`	records, records-ttm, records-move-times, summarize, starttournaments	`GameFactory`, `gameinfo`, `genRecord`, `addResource`
`@abstractplay/recranks`	records, summarize	`APGameRecord`, ELO/Glicko2/Trueskill raters
`ion-js`, `fflate`	dump consumers	Parse gzipped ION export files
`i18next`	records, starttournaments	Email copy (`apback` namespace)

Project layout

src/functions/     Lambda handlers
src/types/         Record and StatSummary TypeScript types
src/locales/       i18n strings (en, fr, it) for tournament emails
src/utils/         Shared utilities (e.g. isoToCountryCode)
scripts/           build-layers.cjs
serverless.yml     Infrastructure and schedules