fix(logs): enhance log streaming with retry mechanism and error handling #3503

uozalp · 2025-08-15T07:16:56Z

Fix log tailing disconnection with Pinniped authentication

Description

Fixes issue where K9s log tailing stops every 5 minutes when using Pinniped authentication due to mTLS certificate expiration. This change adds automatic retry logic to handle credential refresh gracefully during active log streams.

Problem

When using Pinniped authentication, K9s log tailing would fail every 5 minutes with "stream canceled" errors because:

Pinniped uses short-lived mTLS certificates (5-minute expiration) for security
K9s had retry logic for initial connection failures but not for mid-stream disconnects
When credentials expired during an active stream, the connection was terminated without retry

Solution

Enhanced the tailLogs function in internal/dao/pod.go to:

Add a retry loop that handles both initial connection failures and mid-stream disconnects
Automatically reconnect when streams are canceled due to credential expiration
Maintain proper error handling and logging for debugging

Changes

Modified Functions

tailLogs: Added retry loop to handle stream disconnections and reconnection logic (lines 319-379)
readLogs: Signals when stream needs retry instead of terminating (lines 424-472)

Key Improvements

Stream disconnections now trigger automatic reconnection attempts
Up to 20 retry attempts (logRetryCount) with 1-second delays (logRetryWait) between retries
Better error logging to distinguish between recoverable and non-recoverable errors
Uses debug logging (slog.Debug) for retry messages to reduce log noise during normal operation
Maintains compatibility with existing behavior for successful connections

Testing

Verified log tailing continues uninterrupted during Pinniped certificate rotation
Confirmed retry logic works correctly with appropriate debug messages
Tested that canceling log tailing still works as expected
No impact on non-Pinniped authentication methods
Verified reduced log verbosity with debug-level retry messages

Related Issues
Fixes issue where log tailing stops every 5 minutes with Pinniped authentication due to mTLS certificate expiration.

Example Behavior
After the fix, log tailing continues automatically during credential refresh. Debug messages (only visible with debug logging enabled):

DBG Log stream canceled, will retry connection container="pod/container" error="stream canceled read tcp: use of closed network connection"
DBG Log stream ended, retrying connection container="pod/container"

The log tailing continues seamlessly without manual intervention or visible warnings in normal operation.

Backward Compatibility
This change is fully backward compatible:

Existing behavior is preserved for successful connections
No API changes or breaking modifications
Only affects the retry behavior when streams are interrupted
Debug messages reduce log noise compared to warning-level messages

Fixes #3502

…ndling

uozalp · 2025-08-23T14:33:32Z

@derailed any chance you could take a peek at this PR?

derailed

@uozalp Thank you for this update! I think this needs a bit more thought/TLC

internal/dao/pod.go

…ing method

uozalp · 2025-09-01T12:39:37Z

@derailed I've updated the PR to address all your concerns:

Eliminated unused log items - Removed error messages from recoverable cases (request/stream failures during retries)
Added intelligent retry logic - Now checks pod status before retries; stops when pod has DeletionTimestamp or is in terminal state
Clear retry semantics - Only stream errors warrant retries; EOF is treated as legitimate end with no retry
Simplified control flow - Removed streamDone channel; only final retry exhaustion shows error to user

The "blind retry" issue is resolved - we now bail out appropriately when pods are terminated/deleted.

derailed

@uozalp Nice! Thank you for these updates. Looks much better butI think this needs additional TLC.

internal/dao/pod.go

derailed · 2025-09-04T16:01:51Z

internal/dao/pod.go

-		out = make(LogChan, 2)
-		wg  sync.WaitGroup
-	)
+	out := make(LogChan, logChannelBuffer)


We need to be careful here with allocs. This allocated a 100 buffer channel. Why is this necessary?

Prevents the "WRN Dropping log line due to slow consumer" warnings I see on high-volume logging pods

Thanks Umut! I think we need to benchmark this and figure out a sweet spot. Less is more when it comes to buffered channels.

@derailed I’ve reduced it from 100 to 50. My benchmark tests indicated that around 40 was stable on my system, so I settled on 50 to better accommodate slower machines. see my test results below

internal/dao/pod.go

uozalp · 2025-09-04T18:44:29Z

@derailed I've updated the PR to address your feedback. Please see my replies to the individual comments for context on the specific changes.

uozalp · 2025-09-11T10:42:10Z

@derailed I ran some benchmarks on my machine to measure how different logChannelBuffer sizes affect dropped log lines.

Test setup:

CPU: 13th Gen Intel(R) Core(TM) i7-1355U (12 logical cores)
Workload: Traefik pod logs
Metrics collected: total lines, dropped lines, drop rate %, throughput (lines/sec)

Results (summary):

Buffer Size	Avg. Drop Rate	Notes
2	8–13%	Frequent drops
20	~0.5–3%	Some drops remain
25–30	≤1%	Drops rare
35	~0–1%	Mostly stable
40	0%	No measurable drops, stable
60+	0%	No measurable drops, stable

Conclusion:
On my system, the sweet spot is around 40. That’s the smallest buffer size where drops consistently disappear. On faster or slower CPUs the optimal size may shift slightly, but it looks like ~40–60 is a safe range.

Buffer Channel: 2

timestamp	container	total_lines	dropped_lines	drop_rate_percent	lines_per_sec
2025-09-11 11:36:53	addon-traefik/traefik-9zpgj (traefik)	990	117	11.82	66.00
2025-09-11 11:37:08	addon-traefik/traefik-9zpgj (traefik)	1706	150	8.79	56.75
2025-09-11 11:37:24	addon-traefik/traefik-9zpgj (traefik)	1165	159	13.65	77.66

Buffer Channel: 20

timestamp	container	total_lines	dropped_lines	drop_rate_percent	lines_per_sec
2025-09-11 11:50:44	addon-traefik/traefik-9zpgj (traefik)	871	33	3.79	58.06
2025-09-11 11:52:21	addon-traefik/traefik-9zpgj (traefik)	6201	33	0.53	55.30
2025-09-11 11:52:37	addon-traefik/traefik-9zpgj (traefik)	829	1	0.12	55.26

Buffer Channel: 25

timestamp	container	total_lines	dropped_lines	drop_rate_percent	lines_per_sec
2025-09-11 11:55:44	addon-traefik/traefik-9zpgj (traefik)	1016	3	0.30	67.73

Buffer Channel: 30

timestamp	container	total_lines	dropped_lines	drop_rate_percent	lines_per_sec
2025-09-11 11:59:00	addon-traefik/traefik-9zpgj (traefik)	665	13	1.95	44.33

Buffer Channel: 35

timestamp	container	total_lines	dropped_lines	drop_rate_percent	lines_per_sec
2025-09-11 12:07:05	addon-traefik/traefik-9zpgj (traefik)	998	0	0.00	66.53
2025-09-11 12:08:44	addon-traefik/traefik-9zpgj (traefik)	8119	3	0.04	70.67
2025-09-11 12:09:00	addon-traefik/traefik-9zpgj (traefik)	1174	14	1.19	78.26

Buffer Channel: 40 - test 1

timestamp	container	total_lines	dropped_lines	drop_rate_percent	lines_per_sec
2025-09-11 11:45:06	addon-traefik/traefik-9zpgj (traefik)	598	0	0.00	39.87

Buffer Channel: 40 - test 2

timestamp	container	total_lines	lines_per_sec
2025-09-11 12:02:45	addon-traefik/traefik-9zpgj (traefik)	1809	120.59
2025-09-11 12:03:38	addon-traefik/traefik-9zpgj (traefik)	5276	77.91
2025-09-11 12:03:54	addon-traefik/traefik-9zpgj (traefik)	1191	79.40

Buffer Channel: 40 - test 3

timestamp	container	total_lines	lines_per_sec
2025-09-11 12:11:53	addon-traefik/traefik-9zpgj (traefik)	1090	72.66
2025-09-11 12:13:46	addon-traefik/traefik-9zpgj (traefik)	8695	67.71
2025-09-11 12:14:02	addon-traefik/traefik-9zpgj (traefik)	896	59.73
2025-09-11 12:18:46	addon-traefik/traefik-9zpgj (traefik)	20066	67.01
2025-09-11 12:19:02	addon-traefik/traefik-9zpgj (traefik)	1027	68.47

Buffer Channel: 60

timestamp	container	total_lines	dropped_lines	drop_rate_percent	lines_per_sec
2025-09-11 11:47:43	addon-traefik/traefik-9zpgj (traefik)	1048	0	0.00	69.87

derailed

@uozalp Very cool! Well done Sir. Thank you Umut!!

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fix(logs): enhance log streaming with retry mechanism and error handling

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uozalp mentioned this pull request Aug 15, 2025

Log tailing stops every 5 minutes with Pinniped authentication #3502

Closed

Merge branch 'master' into feat/log-retry

c569ee0

uozalp marked this pull request as draft August 15, 2025 07:38

fix(logs): improve log tailing with enhanced retry logic and error ha…

a2c4a13

…ndling

uozalp marked this pull request as ready for review August 15, 2025 07:59

uozalp mentioned this pull request Aug 15, 2025

Feature Request: Configurable Expiration Time for Client Certificate vmware/pinniped#1987

Closed

uozalp and others added 4 commits August 20, 2025 08:37

Merge branch 'master' into feat/log-retry

c2c7083

Merge branch 'master' into feat/log-retry

3aab9d3

renamed function

1787213

Merge branch 'master' into feat/log-retry

69713ae

Merge branch 'master' into feat/log-retry

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derailed requested changes Aug 29, 2025

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internal/dao/pod.go Show resolved Hide resolved

uozalp and others added 3 commits September 1, 2025 14:25

Enhance log streaming with retry logic based on pod status

053d9ee

Refactor Pod struct definition by moving it above the shouldStopRetry…

e93c52d

…ing method

Merge branch 'master' into feat/log-retry

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uozalp requested a review from derailed September 1, 2025 12:39

derailed reviewed Sep 4, 2025

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uozalp and others added 2 commits September 4, 2025 20:27

Implement exponential backoff for log streaming retries

602e2ef

Merge branch 'master' into feat/log-retry

cdc95c8

uozalp requested a review from derailed September 4, 2025 18:44

fix: reduce log channel buffer size to prevent drops

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derailed approved these changes Sep 17, 2025

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derailed merged commit c1d07ea into derailed:master Sep 17, 2025
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derailed mentioned this pull request Sep 17, 2025

Rel v0.50.10 #3564

Merged

uozalp mentioned this pull request Sep 22, 2025

Log view is broken as of v0.50.10 #3577

Closed

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fix(logs): enhance log streaming with retry mechanism and error handling #3503

fix(logs): enhance log streaming with retry mechanism and error handling #3503

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uozalp commented Aug 15, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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Fix log tailing disconnection with Pinniped authentication

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