startup.yml

Full schema reference for the startup configuration file — generator entries, per-generator parameter overrides, and the parameter cascade from eventum.yml.

The startup file is a YAML list of generators that Eventum loads when it starts with eventum run. Each entry identifies a generator directory and can override any generation parameter from eventum.yml.

startup.yml

- id: access-logs
  path: access-logs/generator.yml
  autostart: true

- id: error-logs
  path: error-logs/generator.yml
  live_mode: false
  batch:
    size: 50000

Parameter cascade

Startup entries inherit generation parameters from eventum.yml and can override them individually. The cascade works in one direction:

eventum.yml (defaults) → startup.yml (per-generator overrides)

Any field not specified in a startup entry inherits the value from eventum.yml. This means you only need to specify what differs from the defaults.

For example, if eventum.yml sets timezone: UTC and batch.size: 10000, a startup entry with batch.size: 50000 will use UTC timezone (inherited) but a batch size of 50000 (overridden).

Generator entry fields

Core fields

Parameter	Type	Default	Constraints	Description
`id`	string	—	Required. Non-empty. Must be unique across all entries.	Unique identifier for the generator. Used in API endpoints and logs.
`path`	path	—	Required.	Path to the generator config file. Relative paths are resolved against the `generators_dir` from eventum.yml.
`autostart`	boolean	`true`	—	Whether to start this generator automatically when the application launches. If `false`, the generator is registered but must be started manually via the API.

Execution mode

Parameter	Type	Default	Constraints	Description
`live_mode`	boolean	`true`	—	`true` — events are generated at their scheduled timestamps in real time (live mode). `false` — all events are generated as fast as possible without waiting (sample mode).
`skip_past`	boolean	`true`	—	In live mode, whether to skip timestamps that have already passed when the generator starts. When `false`, Eventum will generate events for past timestamps immediately before catching up to real time.

Variable substitution parameters

Parameter	Type	Default	Description
`params`	mapping	`{}`	Key-value pairs substituted into the generator config via `${params.name}` tokens. Can be flat or nested.

- id: web-logs
  path: web-logs/generator.yml
  params:
    opensearch_host: https://opensearch.prod:9200
    opensearch_user: admin
    log_level: info

These values replace ${params.opensearch_host}, ${params.opensearch_user}, and ${params.log_level} in the generator's generator.yml. See Parameters for more details.

Overridable generation parameters

These fields correspond to the generation section of eventum.yml. Any of them can be set per generator in startup.yml to override the application-level defaults.

timezone

Parameter	Type	Default	Constraints	Description
`timezone`	string	`"UTC"`	Valid IANA timezone (e.g., `UTC`, `America/New_York`, `Europe/London`). Min length: 3.	Timezone used for interpreting and generating timestamps.

batch

Controls how events are grouped before being passed to output plugins:

Parameter	Type	Default	Constraints	Description
`batch.size`	integer or null	`10000`*	>= 1	Maximum number of events per batch.
`batch.delay`	float or null	`1.0`*	>= 0.1	Maximum seconds to wait before flushing a partial batch.

*The defaults of 10000 and 1.0 apply as a pair when neither field is specified. If you set only one, the other defaults to null. At least one of size or delay must be set. When both are set, the batch is flushed when either limit is reached — whichever comes first.

queue

Controls the internal queues between pipeline stages:

Parameter	Type	Default	Constraints	Description
`queue.max_timestamp_batches`	integer	`10`	>= 1	Maximum number of timestamp batches held in the input→event queue. Controls backpressure when the event plugin is slower than input.
`queue.max_event_batches`	integer	`10`	>= 1	Maximum number of event batches held in the event→output queue. Controls backpressure when output plugins are slower than event processing.

Concurrency and ordering

Parameter	Type	Default	Constraints	Description
`keep_order`	boolean	`false`	—	When `true`, output plugins process batches sequentially to preserve chronological order. When `false`, batches may be written concurrently and arrive out of order.
`max_concurrency`	integer	`100`	>= 1	Maximum number of concurrent write operations across all output plugins. Acts as a semaphore to prevent overloading destinations.
`write_timeout`	integer	`10`	>= 1	Timeout in seconds for a single write operation. If an output plugin takes longer than this, the write is cancelled.

Format variants

Startup entries support both nested YAML and dot notation for overriding nested parameters:

Both formats produce identical results — use whichever is more readable for your case.

Nested YAML

- id: my-generator
  path: my-generator/generator.yml
  batch:
    size: 5000
    delay: 0.5
  queue:
    max_timestamp_batches: 20

Dot notation

- id: my-generator
  path: my-generator/generator.yml
  batch.size: 5000
  batch.delay: 0.5
  queue.max_timestamp_batches: 20

Complete example

startup.yml

# High-throughput access log generator — sample mode, large batches
- id: access-logs
  path: access-logs/generator.yml
  autostart: true
  live_mode: false
  timezone: America/New_York
  batch:
    size: 50000
  max_concurrency: 50
  write_timeout: 30
  params:
    opensearch_host: https://opensearch.prod:9200
    opensearch_user: admin

# Real-time error log generator — live mode, ordered output
- id: error-logs
  path: error-logs/generator.yml
  autostart: true
  live_mode: true
  skip_past: true
  keep_order: true
  max_concurrency: 10
  params:
    severity: error

# Metrics generator — registered but not started automatically
- id: metrics
  path: metrics/generator.yml
  autostart: false
  timezone: UTC

startup.yml

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