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kobergj
39 lines
2.3 KiB
Markdown
39 lines
2.3 KiB
Markdown
# Eventhistory
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The `eventhistory` consumes all events from the configured event system like NATS, stores them and allows other services to retrieve them via an event ID.
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## Prerequisites
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Running the eventhistory service without an event system like NATS is not possible.
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## Consuming
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The `eventhistory` services consumes all events from the configured event system.
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## Storing
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The `eventhistory` service stores each consumed event via the configured store in `EVENTHISTORY_STORE`. Possible stores are:
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- `memory`: Basic in-memory store and the default.
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- `redis-sentinel`: Stores data in a configured Redis Sentinel cluster.
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- `nats-js-kv`: Stores data using key-value-store feature of [nats jetstream](https://docs.nats.io/nats-concepts/jetstream/key-value-store)
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- `noop`: Stores nothing. Useful for testing. Not recommended in production environments.
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- `ocmem`: Advanced in-memory store allowing max size. (deprecated)
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- `redis`: Stores data in a configured Redis cluster. (deprecated)
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- `etcd`: Stores data in a configured etcd cluster. (deprecated)
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- `nats-js`: Stores data using object-store feature of [nats jetstream](https://docs.nats.io/nats-concepts/jetstream/obj_store) (deprecated)
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Other store types may work but are not supported currently.
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Note: The service can only be scaled if not using `memory` store and the stores are configured identically over all instances!
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Note that if you have used one of the deprecated stores, you should reconfigure to one of the supported ones as the deprecated stores will be removed in a later version.
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Store specific notes:
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- When using `redis-sentinel`, the Redis master to use is configured via e.g. `OCIS_CACHE_STORE_NODES` in the form of `<sentinel-host>:<sentinel-port>/<redis-master>` like `10.10.0.200:26379/mymaster`.
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- When using `nats-js-kv` it is recommended to set `OCIS_CACHE_STORE_NODES` to the same value as `OCIS_EVENTS_ENDPOINT`. That way the cache uses the same nats instance as the event bus.
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- When using the `nats-js-kv` store, it is possible to set `OCIS_CACHE_DISABLE_PERSISTENCE` to instruct nats to not persist cache data on disc.
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## Retrieving
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Other services can call the `eventhistory` service via a gRPC call to retrieve events. The request must contain the event ID that should be retrieved.
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