Fetch all ip addresses in a single stdlib call #246
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swiatekm
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andrewkroh
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Oct 29, 2024
andrewkroh
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Oct 29, 2024
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When fetching ip addresses for the host, we fetch all the network interfaces, and then ip addresses for each interface. The latter call is surprisingly expensive on unix, as it involves opening a netlink socket, sending a request for routing information, and receiving and parsing the response. If the host has a lot of network interfaces, this can eat surprising amounts of memory - I got in the order of 10 MB on a Kubernetes Node with 100 Pods. See elastic/elastic-agent#5835 (comment) for some heap profiles from elastic-agent.
Instead, get all the addresses in a single stdlib call. We don't actually care about which interface each ip address is attached to, we just want all of them.
I've tested this in the real world scenario discussed in elastic/elastic-agent#5835, not sure how to include a self-contained test in this repo.