csrfr

csrfr

Distributed Services with Go: accessing the service outside the pods (Beta-4 pg.223)

Once deployed, I am not able to access the service outside the prolog pods. I can run the client successfully and access the service from a client running on one of the proglog pods.

However, I am not able to access the service from the following locations:

  1. Laptop: The client connection hangs and then returns connection error while dialing dial tcp: lookup proglog-0.proglog.mysvcs.svc.cluster.local: no such host. I am dialing using the EXTERNAL-IP address of proglog-0 from k8s in the client (This address works when used from a proglog pod).

  2. From a pod in the k8s cluster but not a proglog pod. It prints the following error repeatedly ERROR: 2020/10/31 18:59:29 [core] subconn returned from pick is not *acBalancerWrapper. Also, the acBalancerWrapper error appears when running the client from a proglog pod (where it usually works) from time to time.

Anyone faced this before, ideas?
At the moment I’m looking into GetServers returning the K8s DNS names (e.g. proglog-0.proglog.default.svc.cluster.local:8400 rather than the EXTERNAL-IP of the pods.

Marked As Solved

travisjeffery

travisjeffery

Author of Distributed Services with Go

Yeah we should return ErrNoSubConnAvailable like so:

func (p *Picker) Pick(info balancer.PickInfo) (
	balancer.PickResult, error) {
	p.mu.RLock()
	defer p.mu.RUnlock()
	var result balancer.PickResult
	if strings.Contains(info.FullMethodName, "Produce") ||
		len(p.followers) == 0 {
		result.SubConn = p.leader
	} else if strings.Contains(info.FullMethodName, "Consume") {
		result.SubConn = p.nextFollower()
	}
	if result.SubConn == nil {
		return result, balancer.ErrNoSubConnAvailable
	}
	return result, nil
}

so gRPC will block the RPC until a new picker is available with available sub connections.

Also Liked

travisjeffery

travisjeffery

Author of Distributed Services with Go

For 1. did you port-forward the pod/service to expose it outside k8s’ network? That’s what the $ kubectl port-forward pod/proglog-0 8400 8400 command in the book is for.

  1. Could be because leader election is still underway so a nil subconn is returned for it.
travisjeffery

travisjeffery

Author of Distributed Services with Go

For 2. I think the error handling should be improved. I’m looking into it.

Where Next?

Popular Pragmatic Bookshelf topics Top

New
jon
Some minor things in the paper edition that says “3 2020” on the title page verso, not mentioned in the book’s errata online: p. 186 But...
New
sdmoralesma
Title: Web Development with Clojure, Third Edition - migrations/create not working: p159 When I execute the command: user=> (create-...
New
New
brunogirin
When running tox for the first time, I got the following error: ERROR: InterpreterNotFound: python3.10 I realised that I was running ...
New
dsmith42
Hey there, I’m enjoying this book and have learned a few things alredayd. However, in Chapter 4 I believe we are meant to see the “>...
New
adamwoolhether
Is there any place where we can discuss the solutions to some of the exercises? I can figure most of them out, but am having trouble with...
New
akraut
The markup used to display the uploaded image results in a Phoenix.LiveView.HTMLTokenizer.ParseError error. lib/pento_web/live/product_l...
New
AufHe
I’m a newbie to Rails 7 and have hit an issue with the bin/Dev script mentioned on pages 112-113. Iteration A1 - Seeing the list of prod...
New
Henrai
Hi, I’m working on the Chapter 8 of the book. After I add add the point_offset, I’m still able to see acne: In the image above, I re...
New

Other popular topics Top

DevotionGeo
I know that these benchmarks might not be the exact picture of real-world scenario, but still I expect a Rust web framework performing a ...
New
Rainer
My first contact with Erlang was about 2 years ago when I used RabbitMQ, which is written in Erlang, for my job. This made me curious and...
New
AstonJ
There’s a whole world of custom keycaps out there that I didn’t know existed! Check out all of our Keycaps threads here: https://forum....
New
AstonJ
I have seen the keycaps I want - they are due for a group-buy this week but won’t be delivered until October next year!!! :rofl: The Ser...
New
PragmaticBookshelf
“A Mystical Experience” Hero’s Journey with Paolo Perrotta @nusco Ever wonder how authoring books compares to writing articles?...
New
rustkas
Intensively researching Erlang books and additional resources on it, I have found that the topic of using Regular Expressions is either c...
New
foxtrottwist
A few weeks ago I started using Warp a terminal written in rust. Though in it’s current state of development there are a few caveats (tab...
New
PragmaticBookshelf
Author Spotlight: Tammy Coron @Paradox927 Gaming, and writing games in particular, is about passion, vision, experience, and immersio...
New
New
AnfaengerAlex
Hello, I’m a beginner in Android development and I’m facing an issue with my project setup. In my build.gradle.kts file, I have the foll...
New

Sub Categories: