[bootstrap agent] Need to expose an API to expose version information of host-level software

[smklein]

• This will be necessary for wicket to query for versioning information of host-level software

[smklein]

Going to depend on #2448 to pull this out

[smklein]

I mentioned this in chat with @jgallagher , but I think I need some help here. FYI @sunshowers , @andrewjstone .

Bootstrap agent is currently unwilling to serve requests until the trust quorum has been established:

omicron/sled-agent/src/bootstrap/server.rs

Lines 173 to 210 in e12441e

	async fn run(self) -> Result<(), String> {
	// Do we already have our trust quorum share? If not, we need to wait
	// for RSS to send us a sled agent init request.
	let trust_quorum = match self.trust_quorum {
	TrustQuorumMembership::Uninitialized => {
	self.wait_for_sled_initialization().await?
	}
	TrustQuorumMembership::Known(quorum) => quorum,
	};
	loop {
	let (stream, remote_addr) =
	self.listener.accept().await.map_err(|err| {
	format!("accept() on already-bound socket failed: {err}")
	})?;
	let log = self.log.new(o!("remote_addr" => remote_addr));
	info!(log, "Accepted connection");
	let bootstrap_agent = self.bootstrap_agent.clone();
	let sp = self.sp.clone();
	let trust_quorum = Arc::clone(&trust_quorum);
	tokio::spawn(async move {
	match serve_request_after_quorum_initialization(
	stream,
	bootstrap_agent,
	sp,
	trust_quorum.as_ref(),
	&log,
	)
	.await
	{
	Ok(()) => info!(log, "Connection closed"),
	Err(err) => warn!(log, "Connection failed"; "err" => err),
	}
	});
	}
	}

This means I can't actually expose versioning information before trust quorum - aka, when interacting with Wicket.

My plan is to serve a dropshot server for the bootstrap agent which exposes this versioning information alongside the sockets-based connection, using a different port. Does this seem acceptable to y'all?

[andrewjstone]

ooh, this means we can actually get the host OS and control plane version software from wicket pre-mupdate.

I think this is a great idea. Separate HTTP port on bootstrap network.