Client should send status report on reconnect

[andykellr]

Currently, the status report message is prepared here in client.Start:

opamp-go/client/clientimpl.go

Lines 109 to 113 in 5255de5

	// Prepare the first status report.
	w.sender.UpdateNextStatus(
	func(statusReport *protobufs.StatusReport) {
	statusReport.AgentDescription = w.settings.AgentDescription
	},

It then begins runUntilStopped and in runOneCycle it ensures it is connected before entering the ReceiverLoop to receive massages from the server:

opamp-go/client/clientimpl.go

Lines 313 to 318 in 5255de5

	func (w *client) runOneCycle(ctx context.Context) {
	if err := w.ensureConnected(ctx); err != nil {
	// Can't connect, so can't move forward. This currently happens when we
	// are being stopped.
	return
	}

If the connection is closed, it will repeat runOneCycle and reconnect, but after reconnection no status message is sent because no message has been prepared.

In our own agent, the workaround was to call SetAgentDescription in the OnConnect callback, but I think the implementation should be doing this automatically.

[andykellr]

Here is the section of the spec regarding the agent sending a status report upon connection. I doesn't specifically address reconnecting, but I think this is implied.

https://github.com/open-telemetry/opamp-spec/blob/410dc86792d6109050e767a1d76de12a5b9f0129/specification.md?plain=1#L485-L491

[tigrannajaryan]

Here is the section of the spec regarding the agent sending a status report upon connection. I doesn't specifically address reconnecting, but I think this is implied.

@andykellr you are right. The status report should be sent after reconnecting. Will you be able to submit a PR with a fix?

[dsvanlani]

@tigrannajaryan I'm working on a PR for this, but will not have anything to show by this afternoons work group.