Reintroduce timeout and keep-alive for watch requests to match client-go

[rossanthony]

Thanks to @Alabate for opening the initial PR with this fix: #2131

This PR includes Alabate's fix + unit test coverage. Below is the original PR description copied here for reference:

---

This will send keep-alive probes to the server every 30 seconds. These features were present prior to the 1.0 but were inadvertently removed.

Fixes #2127

Previous relevant issues:

• Initial issue: Unable to detect if a watch is active #559
  • PR: send keep-alive probes every 30 seconds to the server #630
• Improvement: Dependencie net-keepalive does not support win32 #632
  • PR: fix: remove dependency on net-keepalive #635

Implementation details

Setting requestInit.timeout = 30000 is equivalent to socket.setTimeout(30000) as you can see in the sources.

One of the solution suggested in #2127 was to use the keepAlive of the http.Agent. But as documented here, that's just a boolean that instruct the agent that we want sockets to be re-used. We want to send packets at a fixed rate to know when a connection is broken. This can be done with the socket.setKeepAlive() method, but to use it, we need to access the socket object.

I managed to access the socket and call setKeepAlive(), but only after the await fetch(), when the response is already arriving. That's the only way I found to access the socket. The Agent create the socket, but there is no event to know when a socket created, you can just access them by list like I did. There is a socket event on the request object, but node-fetch abstract it away, and I couldn't find a clean way to access it (node-fetch/node-fetch#1720 that request this feature).

The only way I've found to get the socket before the request was by monkey-patching the agent.createConnection(), but I think this solution is worse.

const _createConnection = agent.createConnection;
agent.createConnection = function (...args) {
  const socket = _createConnection.apply(agent, args);
  socket.setTimeout(3000);
  socket.setKeepAlive(true, 3000);
  return socket;
}

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: rossanthony / name: Ross Anthony (fe8d1c1)

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[rossanthony]

/easycla

[brendandburns]

Thanks for finishing this up. I'll let @cjihrig have the final LGTM, but looks good to me.

/approve

[cjihrig]

/approve
/lgtm

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[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: brendandburns, cjihrig, rossanthony

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[rossanthony]

@brendandburns or @cjihrig what's the process for getting a new release cut?