sysdump: don't rely on timeout command to collect hubble flows #38999
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Currently, hubble flows collection in sysdumps relies on the timeout command to set an upper bound on the maximum retrieval time. This is mostly due to historical reasons, as hubble flows used to be collected using the --follow flag. Yet, that is no longer the case since [1], even though the timeout was kept as a safety measure. Let's slightly rework this logic to specify the timeout via the context, rather than relying on the timeout command, to avoid requiring it to be present in the target Cilium agent image. We don't use the so-called kill context here, because that would set tty, which in turn coalescences the stdout and stderr streams together [2], which is undesired. While being there, let's also drop the bash indirection, and directly invoke the hubble binary. [1]: cfc594f ("sysdump: don't specify --follow while collecting hubble flows") [2]: https://github.com/cilium/cilium/blob/21a15af2b0a951ba09432337de6aba2e8e6c0da3/vendor/k8s.io/client-go/tools/remotecommand/remotecommand.go#L44-L49 Signed-off-by: Marco Iorio <marco.iorio@isovalent.com>
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nathanjsweet
approved these changes
Apr 17, 2025
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Currently, hubble flows collection in sysdumps relies on the timeout command to set an upper bound on the maximum retrieval time. This is mostly due to historical reasons, as hubble flows used to be collected using the --follow flag. Yet, that is no longer the case since [1], even though the timeout was kept as a safety measure.
Let's slightly rework this logic to specify the timeout via the context, rather than relying on the timeout command, to avoid requiring it to be present in the target Cilium agent image. We don't use the so-called kill context here, because that would set tty, which in turn coalescences the stdout and stderr streams together [2], which is undesired.
While being there, let's also drop the bash indirection, and directly invoke the hubble binary.
[1]: cfc594f ("sysdump: don't specify --follow while collecting hubble flows")
[2]:
cilium/vendor/k8s.io/client-go/tools/remotecommand/remotecommand.go
Lines 44 to 49 in 21a15af