Re: tcp_diag for all network namespaces?

[Cong Wang <xiyou.wangcong@gmail.com>]

On Mon, Dec 09, 2024 at 11:24:18AM -0800, dave seddon wrote:
> G'day,
> 
> Short
> Is there a way to extract tcp_diag socket data for all sockets from
> all network name spaces please?
> 
> Background
> I've been using tcp_diag to dump out TCP socket performance every
> minute and then stream the data via Kafka and then into a Clickhouse
> database.  This is awesome for socket performance monitoring.
> 
> Kubernetes
> I'd like to adapt this solution to <somehow> allow monitoring of
> kubernetes clusters, so that it would be possible to monitor the
> socket performance of all pods.  Ideally, a single process could open
> a netlink socket into each network namespace, but currently that isn't
> possible.
> 
> Would it be crazy to add a new feature to the kernel to allow dumping
> all sockets from all name spaces?

You are already able to do so in user-space, something like:

for ns in $(ip netns list | cut -d' ' -f1); do
    ip netns exec $ns ss -tapn
done

(If you use API, you can find equivalent API's)

Thanks.