adding drop bytes and drop packets count metric

[yash97]

Issue #, if available:

solves #229
Description of changes:
This PR enhances the network policy agent by adding packet length and direction information to policy events. These additions enable the export of more detailed metrics, specifically:

1. Packet drop counts with direction
2. Packet drop bytes with direction

Sample Output of metrics:

We have prometheus port setup here Code Customer can use Prometheus or other tool to scrape metrics.

 curl localhost:61680/metrics

# HELP network_policy_drop_bytes_total Total number of bytes dropped by network policy agent
# TYPE network_policy_drop_bytes_total counter
network_policy_drop_bytes_total{direction="ingress"} 1.0665324e+07
# HELP network_policy_drop_count_total Total number of packets dropped by network policy agent
# TYPE network_policy_drop_count_total counter
network_policy_drop_count_total{direction="ingress"} 144126

Important Notes

These metrics will only be measured if the --enable-policy-event-logs flag is set to true.

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.

[orsenthil]

Why do we use unsigned 8 here? Is it this a reference from kernel data structure or since the value be 0 or 1 we chose the __u8 ?

[yash97]

Its just to store boolean value

[Pavani-Panakanti]

@yash97 How are these metrics being exposed to cx and how can cx use these metrics for monitoring ?

[yash97]

@Pavani-Panakanti cx can scrape metrics through open prometheus port.