pubsub: deadline exceeds when behind VPN

[boranby]

Client

PubSub

Environment

Redhat Enterprise Linux (no container)

Code and Dependencies

package main

func main() {
  // ...
  client, err := pubsub.NewClient(ctx, projectID)
  // ...
  t := client.Topic(topicID)
  // ...
  msg, err := proto.Marshal(message)
  result := t.Publish(ctx, &pubsub.Message {
    Data: msg,
  })

  id, err := result.Get(ctx)
  if err != nil {
    return fmt.Errorf("pubsub: Get: %w", err)
  }
  log.Printf("Published a message; msg ID: %v\n", id)
}

go.mod

module modname

go 1.23.0

require (
  cloud.google.com/go/pubsub v1.44.0
  google.golang.org/protobuf v1.35.1
)

Expected behavior

It shouldn't matter for Pub/Sub client that the computer it runs has an open VPN connection. It should publish without any issues.

Actual behavior

If I enable VPN to access a private network from the machine, Pub/Sub publish returns context deadline exceeded error. When I close the VPN, it publishes and get the id of the publish. It can generate the client, get the Topic, list the topics. However, it stucks at the result.Get(ctx).

[hongalex]

Thanks for filing this issue.

1. Is this something that has always happened, or started happening v1.44.0?
2. Just to clarify, are you actually calling c.Topics in your code when you say you "list the topics"? I couldn't find it in that snippet you listed above and I wonder if the first API call being made is actually Publish
3. Can you test that this happens with any other gRPC-based library (e.g. with Firestore or any other Go library in this repo)

[boranby]

Hi @hongalex , thanks for your quick response.

1. I started development with v1.44.0, I haven't tried the previous versions.
2. You are right. It can't also list the topics. I commented out the list topics sections and remember it wrong, it also stuck.
3. Tried using this example. https://github.com/GoogleCloudPlatform/golang-samples/blob/main/firestore/increment.go It also stuck at the line dc.Update

[hongalex]

Hm, given that this issue occurs with other products like Firestore, this likely isn't an issue with our library specifically. I would recommend checking your VPN settings to narrow down the issue: is it an issue with gRPC specifically or do HTTP calls also timeout? Is it something to do with the VPN connection itself?