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:
-
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). -
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
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
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.
- Could be because leader election is still underway so a nil subconn is returned for it.
travisjeffery
For 2. I think the error handling should be improved. I’m looking into it.
Popular Pragmatic Bookshelf topics
Other popular topics
Categories:
Sub Categories:
Popular Portals
- /elixir
- /rust
- /wasm
- /ruby
- /erlang
- /phoenix
- /keyboards
- /python
- /js
- /rails
- /security
- /go
- /swift
- /vim
- /clojure
- /java
- /emacs
- /haskell
- /typescript
- /svelte
- /onivim
- /kotlin
- /c-plus-plus
- /crystal
- /tailwind
- /react
- /gleam
- /ocaml
- /elm
- /vscode
- /flutter
- /ash
- /html
- /deepseek
- /opensuse
- /zig
- /centos
- /php
- /scala
- /react-native
- /lisp
- /sublime-text
- /textmate
- /nixos
- /debian
- /agda
- /deno
- /django
- /kubuntu
- /arch-linux
- /nodejs
- /spring
- /ubuntu
- /revery
- /manjaro
- /diversity
- /julia
- /lua
- /markdown
- /quarkus
Devtalk Sponsors
Practical resources that improve the lives of professional developers.
We build trusted fault-tolerant systems that scale to billions of users.
Real-time error tracking, performance insights, and observability for devs.
Supporting innovation across the BEAM ecosystem.
We build reliable cloud platforms for business-critical systems.
Develop your skills with books, videos, and courses.
Catch errors, track performance, monitor hosts and more.
Enabling companies to succeed by building software people love.
Courses that move you from confusion to "Aha, now I get it!"
Publishing Linux Magazine, ADMIN, and MakerSpace for 25+ years.