Special: Caching Events

Tracee has an events caching (in-memory) mechanism. In order to check latest caching options you may execute:

$ ./dist/tracee --cache help

Read

Before continuing, please read the architecture page, in order to understand the tracee pipeline concept, AND the [performance page], to understand possible pain points.

The caching happens in userland, it is an in-memory caching, and it helps with workload bursts: if kernel produces more events than userland is capable of processing then the events are kept in a sizeable cache (defined by user) so they're not lost (if cache isn't full).

The effects of this are the following:

1. Detections might be delayed because of workload bursts, but not lost (if cache isn't full).

2. Event losses from the kernel perf/ring buffer will only happen when cache is full.

3. Any difference in ratio production:consumption can be mitigated temporarily.

Use caching

Example using 1GB cache, container enrichment in the pipeline, argument parsing so arguments are formatted in a human consumable way:

$ sudo ./dist/tracee \
    --cache cache-type=mem \
    --cache mem-cache-size=1024 \
    --containers -o format:json \
    -o option:parse-arguments \
    -trace container \
    --crs docker:/var/run/docker.sock

We are using most of the options that could cause latencies in the event pipeline BUT we're not piping the events to tracee-rules.

Attention

If you pipe tracee output to another tool, like jq:

| jq -c '. | {cgroupid, processname, containername}'

You may cause latencies in tracee pipeline because the event json processing from jq might not be as fast as how tracee is capable of writing events to it (just like tracee-rules could do if being slow evaluating events).