Bug/Doc: Producer connection refused if not using `.load_balancer_mode(true)`

[chevdor]

Describe the bug

This is probably more an information to add to the doc/examples than a bug per say.
A hint in the error message could also save some time :)

I am hosting a RabbitMQ instance in K8s, not using a LoadBalancer but using Traefik.
Running a consumer with:

	let environment = Environment::builder()
		.host("rabbitmq.sample.org")
		.username("user")
		.password("pass")
		// .port(5552)
		.build()
		.await?;

works fine.

Running a producer with the same:

	let environment = Environment::builder()
		.host("rabbitmq.sample.org")
		.username("user")
		.password("pass")
		// .port(5552)
		.build()
		.await?;

fails with:
Error: Client(Io(Os { code: 61, kind: ConnectionRefused, message: "Connection refused" }))

The producer however does connect sucessfully when using:

	let environment = Environment::builder()
		.host("rabbitmq.sample.org")
		.username("user")
		.password("pass")
		.load_balancer_mode(true)                        // REQUIRED
		// .port(5552)
		.build()
		.await?;

Reproduction steps

see above

Expected behavior

Hint in the doc/error message about .load_balancer().
I did not find any other mention other than this PR.

Additional context

No response

[JiaYingZhang]

sry, I implemented it. Have you solved this problem? I never used Traefik, could you provide more information?
@chevdor

[chevdor]

I have solved the problem using .load_balancer_mode(true), the issues actually were that:

• it was not very documented and it took some digging into the code to find this .load_balancer_mode(true)
• the behavior of using .load_balancer_mode(true) and what it does was rather unclear to me
• since I am not using a load balancer (but you may consider that Traefik counts as such), it did not jump at me that using .load_balancer_mode(true) was key to solving the issue.

[JiaYingZhang]

@chevdor
In fact, I was as confused as you before I implemented it.
It was not until I saw this blog