feat(metrics): instrument pipeline channels

[NDStrahilevitz]

1. Explain what the PR does

c826cb3 feat(metrics): instrument pipeline channels

c826cb3 feat(metrics): instrument pipeline channels

Add a new ChannelMetrics type to track the size of the channels in the
pipeline. This can be used to detect bottlenecks in the pipeline. The
channels are registered by name in the handleEvents function. When
tracee is healthy the gauges should mostly be 0.

2. Explain how to test it

Start tracee with the --metrics flag
Go to the metrics url (usually localhost:3366/metrics if server is local)
Confirm that the pipeline channels show up at the bottom
Induce high throughput
Refresh a few times and you should occasionally see one of the stages with a number above 0 (under healthy function this is what should happen)

3. Other comments

[Copilot]

Pull Request Overview

This PR instruments pipeline channels by adding a generic ChannelMetrics type to track their sizes, registering those metrics with Prometheus, and populating the stats in the event handling pipeline.

• Introduce ChannelMetrics in pkg/metrics for both Prometheus registration and JSON output
• Wire up Stats.Channels in pkg/ebpf/events_pipeline.go for each pipeline stage
• Register channel gauges in Stats.RegisterPrometheus

Reviewed Changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
pkg/metrics/stats.go	Added Channels to Stats, initialized in NewStats, and registered in RegisterPrometheus
pkg/metrics/channels.go	Implemented ChannelMetrics type with RegisterChannels and MarshalJSON
pkg/ebpf/events_pipeline.go	Populated stats.Channels[...] for each pipeline stage
pkg/containers/containers.go	Refactored EnrichCgroupInfo for consistent variable naming and map updates
.github/workflows/pr-sync.yaml	Installed git, configured safe.directory, and added error checks in PR sync workflow

Comments suppressed due to low confidence (1)

pkg/metrics/channels.go:10

• Add unit tests for ChannelMetrics.MarshalJSON and RegisterChannels to verify correct JSON serialization and Prometheus metric registration for each channel.

type ChannelMetrics[T any] map[string]<-chan T