as far as I know, you cannot capture a SIGTERM signal

Actually you can capture SIGTERM, and it's what kubernetes sends to a pod when it requests a graceful shutdown. 30 seconds later it'll send SIGKILL which can't be captured, maybe that's what you're thinking of?

It can be tested by running the proxy locally and running kill -15 <pid>.

See https://cloud.google.com/blog/products/gcp/kubernetes-best-practices-terminating-with-grace

I see, indeed they suggest so. I tried it with a simple example and it didn't seem to work:

▶ cat t.go 
package main

import (
    "fmt"
    "os"
    "os/signal"
    "syscall"
)

func main() {

    sigs := make(chan os.Signal, 1)
    done := make(chan bool, 1)

    signal.Notify(sigs, syscall.SIGINT, syscall.SIGTERM)

    go func() {
        sig := <-sigs
        fmt.Println()
        fmt.Println(sig)
        done <- true
    }()

    fmt.Println("awaiting signal")
    <-done
    fmt.Println("exiting")
}

▶ go run t.go
awaiting signal
^C
interrupt
exiting

▶ go run t.go  
awaiting signal
[1]    17141 terminated  go run t.go

As you can see, in the second execution I am sending kill -15 <pid> and it's not catching the signal (but I may be missing something),

Curiously I tried your example.
When running with go run foo.go it seems to make two processes, when I sent sigterm to the binary in /tmp it worked as expected.
i.e. the second entry in this ps output

Compiling with go build foo.go and doing the same with the produced binary should work as well.

Anyway thanks for being so responsive!
I hope to get the node runtime doing the same soon.

Oh, I see, good to know, thanks for following up!

it may be useful to configure this timeout, maybe we should add a env var to be able to change the default value?

I've added an env var SHUTDOWN_TIMEOUT to control this.