Add kubectl retina debug drop command for real-time packet drop monitoring by Copilot · Pull Request #1673 · microsoft/retina

Copilot · 2025-06-09T21:16:44Z

This PR implements a new kubectl retina debug drop command that provides real-time monitoring of packet drop events using eBPF, converting the drop debug script functionality into a Go-based CLI subcommand.

Features

Real-time monitoring: Uses the existing dropreason plugin to capture drop events live
Console formatting: Dynamic output formatting with word wrapping to fit terminal width
File output: Optional file writing capability via --output flag
User confirmation: Prompts for confirmation before invasive operations like port-forwarding
IP filtering: Filter events by specific IP addresses using --ips flag
Error handling: Comprehensive error messages for common eBPF permission issues

Usage

# Basic usage - monitor for 30 seconds
kubectl retina debug drop

# Monitor for specific duration and save to file
kubectl retina debug drop --duration=60s --output=drops.log

# Filter by IP addresses
kubectl retina debug drop --ips=10.0.0.1,10.0.0.2

# Skip confirmation prompts
kubectl retina debug drop --confirm=false

Output Format

TIMESTAMP            SRC_IP          DST_IP          PROTO      DROP_REASON          DETAILS
21:30:15.123         10.0.0.1        10.0.0.2        TCP        DROP(42)             Connection refused
21:30:15.456         10.0.0.3        10.0.0.4        UDP        DROP(13)             No route to host

Implementation Details

Command structure: Added debug command group under cli/cmd/debug/
Integration: Leverages existing pkg/plugin/dropreason plugin via event channels
Architecture: Follows established CLI patterns from capture commands
Testing: Comprehensive test coverage for flags, defaults, and functionality
Documentation: Complete documentation in new docs/05-Debug/ section

Requirements

Linux environment with eBPF support
Sufficient privileges for eBPF operations (may require sudo)
Modern kernel version (4.9+)

The command provides helpful error messages when eBPF capabilities are not available, guiding users on common resolution steps.

Fixes #1672.

💡 You can make Copilot smarter by setting up custom instructions, customizing its development environment and configuring Model Context Protocol (MCP) servers. Learn more Copilot coding agent tips in the docs.

Co-authored-by: matmerr <6521405+matmerr@users.noreply.github.com>

kamilprz · 2025-06-19T14:33:42Z

-// Place holder header file that will be replaced by the actual header file during runtime
-// DO NOT DELETE
+#define ADVANCED_METRICS 1 
+#define BYPASS_LOOKUP_IP_OF_INTEREST 0 


this should not be part of the PR

Fixed in commit 222d88e - reverted the dynamic.h file that was not part of the intended changes.

kamilprz · 2025-06-19T14:35:52Z

+	Long:  "Debug network issues using various Retina debugging tools",
+}
+
+func init() {


There could be some conflicts with the refactor going on at - #1693

kamilprz · 2025-06-19T14:37:11Z

+	dropCmd.Flags().StringVar(&dropOpts.podName, "pod-name", "", "Specific pod name to monitor (optional)")
+	dropCmd.Flags().StringSliceVar(&dropOpts.ips, "ips", nil, "IP addresses to filter for (optional)")
+	dropCmd.Flags().BoolVar(&dropOpts.verbose, "verbose", false, "Enable verbose output")
+	dropCmd.Flags().IntVar(&dropOpts.consoleWidth, "width", 0, "Console width for formatting (auto-detected if 0)")


I don't see a reason to have consoleWidth as a flag. It should always just auto-detect.

Fixed in commit 222d88e - removed the --width flag and made console width auto-detection the only behavior. The consoleWidth is now always automatically detected from the terminal.

kamilprz · 2025-06-19T14:39:06Z

+
+The `kubectl retina debug drop` command monitors packet drop events in real-time using eBPF technology. This helps network operators and developers quickly identify and troubleshoot packet loss issues.
+
+**Key Features:**


Number of linting errors here. Need to be fixed.

Fixed in commit 222d88e - resolved all markdown linting errors in docs/05-Debug/00-overview.md including missing blank lines around lists, language specification for code blocks, and proper file ending.

kamilprz · 2025-06-19T14:39:28Z

+
+The command displays drop events in a tabular format:
+
+```


Some linting errors here. Need to be fixed.

Fixed in commit 222d88e - resolved all markdown linting errors in docs/05-Debug/01-cli.md including proper heading formatting, blank lines around code blocks, and language specification.

kamilprz · 2025-06-19T14:46:09Z

+	RunE: runDropCommand,
+}
+
+func init() {


The script under scripts/watch_drops.sh states Poll drop counters on a specific node every INTERVAL seconds (default 30). The go code in this change does not have a configurable interval

Fixed in commit 222d88e - added --interval flag with 1s default to match the configurable interval functionality in watch_drops.sh script. The interval controls the MetricsInterval configuration for the dropreason plugin.

…g, revert dynamic.h Co-authored-by: kamilprz <36544756+kamilprz@users.noreply.github.com>

Initial plan for issue

c36c097

Copilot AI assigned Copilot and matmerr Jun 9, 2025

Copilot started work on behalf of matmerr June 9, 2025 21:16 View session

Copilot AI and others added 2 commits June 9, 2025 21:31

Add debug drop command structure and basic implementation

1fefba5

Co-authored-by: matmerr <6521405+matmerr@users.noreply.github.com>

Complete debug drop command implementation with tests and documentation

1f557ab

Co-authored-by: matmerr <6521405+matmerr@users.noreply.github.com>

Copilot AI changed the title ~~[WIP] Krew plugin watching for drop events~~ Add kubectl retina debug drop command for real-time packet drop monitoring Jun 9, 2025

Copilot AI requested a review from matmerr June 9, 2025 21:39

Copilot finished work on behalf of matmerr June 9, 2025 21:39

Merge branch 'main' into copilot/fix-1672

bcc477f

kamilprz reviewed Jun 20, 2025

View reviewed changes

Copilot started work on behalf of kamilprz June 20, 2025 07:54 View session

Address PR feedback: remove width flag, add interval flag, fix lintin…

222d88e

…g, revert dynamic.h Co-authored-by: kamilprz <36544756+kamilprz@users.noreply.github.com>

Copilot AI requested a review from kamilprz June 20, 2025 08:05

Copilot finished work on behalf of kamilprz June 20, 2025 08:05

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

Add kubectl retina debug drop command for real-time packet drop monitoring#1673

Add kubectl retina debug drop command for real-time packet drop monitoring#1673
Copilot wants to merge 5 commits intomainfrom
copilot/fix-1672

Copilot AI commented Jun 9, 2025 •

edited

Loading

Uh oh!

kamilprz Jun 19, 2025

Uh oh!

Copilot AI Jun 20, 2025

Uh oh!

kamilprz Jun 19, 2025

Uh oh!

kamilprz Jun 19, 2025

Uh oh!

Copilot AI Jun 20, 2025

Uh oh!

kamilprz Jun 19, 2025

Uh oh!

Copilot AI Jun 20, 2025

Uh oh!

kamilprz Jun 19, 2025

Uh oh!

Copilot AI Jun 20, 2025

Uh oh!

kamilprz Jun 19, 2025

Uh oh!

Copilot AI Jun 20, 2025

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

3 participants


		The `kubectl retina debug drop` command monitors packet drop events in real-time using eBPF technology. This helps network operators and developers quickly identify and troubleshoot packet loss issues.

		Key Features:

Conversation

Copilot AI commented Jun 9, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Features

Usage

Output Format

Implementation Details

Requirements

Uh oh!

kamilprz Jun 19, 2025

Choose a reason for hiding this comment

Uh oh!

Copilot AI Jun 20, 2025

Choose a reason for hiding this comment

Uh oh!

kamilprz Jun 19, 2025

Choose a reason for hiding this comment

Uh oh!

kamilprz Jun 19, 2025

Choose a reason for hiding this comment

Uh oh!

Copilot AI Jun 20, 2025

Choose a reason for hiding this comment

Uh oh!

kamilprz Jun 19, 2025

Choose a reason for hiding this comment

Uh oh!

Copilot AI Jun 20, 2025

Choose a reason for hiding this comment

Uh oh!

kamilprz Jun 19, 2025

Choose a reason for hiding this comment

Uh oh!

Copilot AI Jun 20, 2025

Choose a reason for hiding this comment

Uh oh!

kamilprz Jun 19, 2025

Choose a reason for hiding this comment

Uh oh!

Copilot AI Jun 20, 2025

Choose a reason for hiding this comment

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

3 participants

Copilot AI commented Jun 9, 2025 •

edited

Loading