calicovppctl: improve capture file transfer robustness#869
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Good catch, thanks for taking a stab at it !
A few comments inline
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Replace kubectl exec shell command with Kubernetes Go client API (remotecommand) for streaming capture files. This improves error handling and avoids shell-related issues. Key changes: - Use k8s.io/client-go/tools/remotecommand for file streaming instead of exec.Command with kubectl - Add retry logic (3 attempts) for file transfer to handle transient network issues - On transfer failure, print manual recovery instructions and preserve remote files for manual retrieval - Clean up pre-existing capture files before starting new captures to prevent stale capture data - Extend 'capture clear' command to also remove remote capture files (/tmp/trace.txt, /tmp/trace.pcap, /tmp/dispatch.pcap and .gz variants) Signed-off-by: Aritra Basu <aritrbas@cisco.com>
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Summary
This PR improves the robustness of capture file downloads in
calicovppctlfortrace,pcap, anddispatchcommands.Problem
Large capture file downloads using
kubectl cpwere unreliable, often failing mid-transfer with generic errors forcing users to rerun entire captures when the transfer failed.Changes
1. Use Kubernetes Go Client API Instead of Shell Exec
Replace
exec.Command(kubectl ...)with the native Kubernetes Go client API (k8s.io/client-go/tools/remotecommand). This provides better error handling with structured errors through direct integration with the existing Kubernetes client.2. Retry Logic for File Transfer
Add retry mechanism (3 attempts) for file transfers. This handles transient network issues that commonly cause failures with large capture files.
3. Graceful Failure with Manual Recovery
When file transfer fails after all 3 retry attempts:
calicovppctl capture clearfor cleanup after manual retrieval4. Pre-existing File Cleanup
Before starting a new capture, any pre-existing capture file is removed. This ensures fresh captures without stale data and prevents accidental appending to pre-existing capture files.
5. Enhanced
capture clearCommandThe
capture clearcommand now also removes remote capture files:/tmp/trace.txtand/tmp/trace.txt.gz/tmp/trace.pcapand/tmp/trace.pcap.gz/tmp/dispatch.pcapand/tmp/dispatch.pcap.gz