Crate chronon 

Chronon — cron and run-once scheduling for Rust services.

Chronon provides typed script handlers, durable job/run history, and optional coordinator–worker split behind a thin SchedulerStore port. Feature-gated backends and HTTP adapters sit behind the public facade.

Getting started

Cargo examples are not auto-indexed by rustdoc. Use the table below (also in chronon/README.md), or cargo run -p uf-chronon --example <name> --features ….

Example	Shows	Features
script_macro	#[chronon::script] + Job::new + upsert_job + tick	mem
script_handle_job	Macro ScriptHandle → default job + typed params	mem
run_now	Manual job + CoordinatorService::run_now	mem
embedded_tick	Due job enqueue via tick_once	mem
store_router_boot	Global StoreRouter install	mem
sqlite_boot	SQLite store boot	sqlite
postgres_boot / postgres_redis_boot	Durable backends	postgres / postgres,redis
axum_host	Mount HTTP router	mem,axum
coordinator_daemon / worker_daemon	Split deployment shapes	postgres,redis

Documentation map

Full snippets live on the linked items (not repeated here).

• Boot the runtime — ChrononBuilder, DeploymentShape, Chronon::run
• Define scripts — script attribute, ScriptContext, ContextFactory
• Schedule a job — Job, CoordinatorService::upsert_job, typed defaults via ScriptHandle
• Run immediately — CoordinatorService::run_now (manual / on-demand)
• Persist jobs and runs — SchedulerStore, Run
• Manage jobs programmatically — CoordinatorService
• Parse cron — CronExpr
• Register storage — install_default_mem_store (mem feature), StoreRouter
• HTTP API — chronon_router (axum feature)
• Metrics — TelemetrySink

Configuration

Settings merge in this order: explicit ChrononBuilder values override environment defaults where both exist.

Setting	Builder API	Environment	Default
Store	.scheduler_store() / .scheduler_store_from_global()	—	required
Context factory	.context_factory()	—	NoOpContextFactory
Telemetry	.telemetry_sink()	—	NoOpSink
Script registry	.script_registry() / .auto_registry()	—	empty or inventory
Tick interval	.tick_interval_ms()	CHRONON_TICK_INTERVAL_MS	250 ms
Instance id	.instance_id()	—	random UUID
Partition count	— (env only)	CHRONON_NUM_PARTITIONS	64

Backend connection (pass to store constructors, not ChrononBuilder)

Backend	Configuration
PostgreSQL	URL to PostgresSchedulerStore::connect; CHRONON_POSTGRES_URL / CHRONON_TEST_POSTGRES_URL for tests
SQLite	Path or URL to SqliteSchedulerStore
Redis overlay	URL to RedisQueueLayer::connect; optional key prefix (default chronon); CHRONON_REDIS_URL in production

Lease TTLs, tick batch limits, worker pool, and worker concurrency are environment-only. See chronon-scheduler crate documentation for the full environment variable table.

Cargo features

No features are enabled by default. Enable explicitly:

Feature	Type	Status
mem	InMemorySchedulerStore	Ready — tests and local dev
sqlite	SqliteSchedulerStore	Ready — embedded file-backed
postgres	PostgresSchedulerStore	Ready — shared durable
redis	PostgresRedisSchedulerStore	Ready — Postgres + Redis claim overlay (requires postgres feature)
axum	chronon_router, HTTP DTOs	Ready — mount on host Axum server
telemetry-console	Documents ConsoleSink usage	Optional marker (ConsoleSink always re-exported)

Re-exports

pub use quark::inventory;

pub use chronon_core as core;

Modules

prelude

Curated re-exports for application developers building Chronon worker binaries.

Structs

Chronon

Assembled Chronon runtime: store, scheduler, executor, and deployment loops.

ChrononBuilder

Builds a crate::Chronon runtime with explicit adapter injection.

ConsoleSink

Writes telemetry to stderr (development and bench).

CoordinatorService

Object-safe coordinator operations backed by SchedulerStore.

CronExpr

A parsed cron expression ready for next-run calculations.

NoOpSink

Discards all telemetry (default for tests and minimal hosts).

ScriptDescriptor

Descriptor for a registered script.

ScriptHandle

A typed handle for scheduling a script with specific parameters.

ScriptRegistry

In-memory script registry with optional link-time inventory discovery.

Enums

ChrononError

Errors that can occur in Chronon operations.

DeploymentShape

Named deployment assembly — not a global mode enum.

Traits

TelemetrySink

Host-injectable telemetry sink for scheduler and executor metrics/events.

Functions

builder

Shorthand for ChrononBuilder::new.

Type Aliases

Result

Result type alias for Chronon operations.

Attribute Macros

script

Marks an async function as a Chronon script, enabling automatic registration and typed parameter handling.