Improve resiliency around orchestrator.strn.pl

[lidel]

iiuc multiple DoS vectors exist around cases when:

• we run out of useful L1s
• HTTP server running orchestrator is down (Amazon has hiccups every year..)
• orchestrator.strn.pl has a hiccup (misconfiguration, attac) and returns too few, or no useful L1s

Each one of these events is unlikely, but the risks compound.
Some ideas for anticipatory action:

• maintain a separate, append-only list of L1s returned by orchestrator, and use it as a backup when orchestrator is down, or does not provide any useful L1s
  • @aarshkshah1992 iiuc we already keep old L1s around when orchestrator fails to refresh, but we remove L1s pruned by orchestrator. This means if there is a bug and orchestrator returns empty list (or only a few slow L1s), we are in trouble.
• DNS idea 1: fallback to https://l1s.strn.pl or https://strn.pl
  • probably not the best idea, iiuc it always points at the closest L1, so using this could overload "best" L1s
• DNS idea 2: use DNS-based orchestrator as a backup mirror of HTTP one
  • Instead of sending HTTP request to a centralized server, leverage DNS for caching and distribution.
  • Saturn has two domains, so we have two "DNS mirrors"
  • we could have all.l1s.strn.pl or nearby.l1s.strn.pl which returns more than one A record, replacing the need for HTTP request https://orchestrator.strn.pl/nodes/nearby?count=9999 – @guanzo thoughts on feasibility?

Other ideas how we can improve resiliency for the day Amazon fails?

cc @aarshkshah1992 @willscott @guanzo

[guanzo]

Idea: Saturn provides bootstrap nodes (could be L1s run by PL) that host a periodically updated list of L1s.

Smart clients like Caboose/serviceworker can hardcode the bootstrap node ip addresses in their code and fetch the list of L1s as a fallback.

That's similar to how the IPFS bootstrap nodes work, right? https://docs.ipfs.tech/how-to/modify-bootstrap-list/

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DNS idea 2 is feasible. I like having 1 global list (ALL IPS), and 1 nearby list. If the nearby list returns 0 then you can fallback to the global list.

[lidel]

If possible, we should avoid hard-coding HTTP endpoints as "bootstrappers" – this is the very problem we are trying to solve :)

The libp2p bootstrappers are bit different,

• it is something we should rely on only during the first cold boot, once we learn about other peers.
  • there is wip work to remember peers and and use for future bootstraps.
• Sidenote: bootastrappers use multiaddrs with /p2p/peerid suffix, which makes them way more resilient than HTTP URLs. it may not matter much for bootstrapper use case, but matters for peering agreements: even when IP is unreachable, or DNS is down, Kubo might be able to reach out to them if LAN DHT or local peer knows their alternative location

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I think if we invest time in this, DNS idea 2 gives us the biggest return in resiliency, because of how DNS hierarchical caching works. And thanks to DoH, we can still use it in browser contexts: https://www.npmjs.com/package/dns-over-http-resolver

So we still can read orchestrator nodes over HTTP, but we no longer need to hardcode specific URL, any DoH endpoint will work.