fix(metrics): fallback to mock writer on file open failure to prevent panic#596
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abhaygoudannavar wants to merge 2 commits intourunc-dev:mainfrom
Open
fix(metrics): fallback to mock writer on file open failure to prevent panic#596abhaygoudannavar wants to merge 2 commits intourunc-dev:mainfrom
abhaygoudannavar wants to merge 2 commits intourunc-dev:mainfrom
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When timestamps are enabled but the target file cannot be opened (e.g. missing directory), NewZerologMetrics returned nil. This caused a nil pointer dereference on subsequent metrics.Capture() calls. This fix gracefully degrades to a no-op mockWriter and logs a warning. Signed-off-by: abhaygoudannavar <abhaysgoudnvr@gmail.com>
Added TestZerologMetricsInvalidFileDoesNotPanic to ensure that if the metrics log file cannot be opened, it gracefully degrades instead of causing a nil pointer dereference. Signed-off-by: abhaygoudannavar <abhaysgoudnvr@gmail.com>
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Hello @abhaygoudannavar , please do not overwrite the PR description. Read the contribution guide for more information. |
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@cmainas i have updated the PR description as asked for now it can be merged. |
cmainas
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May 8, 2026
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cmainas
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Hello @abhaygoudannavar ,
you have linked a PR instead of the issue in the description. Also, I left a comment for the unit test.
| writer := NewZerologMetrics(true, invalidPath, "container-test") | ||
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| // Before the fix, writer would be nil here. | ||
| if writer == nil { |
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Please use assert or require as we do here https://github.com/abhaygoudannavar/urunc/blob/51ba5c5bdb297c93970e0b440a4a31a3a6072f6c/pkg/unikontainers/config_test.go
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Description
When timestamps are enabled in the urunc configuration (
/etc/urunc/config.toml) but the target file path is invalid or the parent directory does not exist,NewZerologMetrics()returnsnil. Because the caller assigns this directly without a nil check, any subsequentmetrics.Capture()calls result in a nil pointer dereference, crashing urunc silently.This PR fixes the issue by returning a
&mockWriter{}(safe no-op fallback) and logging a warning instead of returningnilon file open failure. This ensures urunc gracefully disables metrics rather than panicking.Related issues
How was this tested?
/etc/urunc/config.tomlwithenabled = trueand destination set to a non-existent directory (/var/log/urunc/timestamps.log).sudo nerdctl run --rm --runtime io.containerd.urunc.v2 harbor.nbfc.io/nubificus/urunc/nginx-qemu-unikraft-initrd:latest.uruncstarts normally, logs a warning about the file, and gracefully disables metrics without crashing.make unittestto ensure no existing tests were broken.LLM usage
No usage
Checklist
make lint).make test_ctr,make test_nerdctl,make test_docker,make test_crictl).