From 7c809a003883d72c066ae9a7a377a5c0e38920ae Mon Sep 17 00:00:00 2001
From: r-vdp <ramses@well-founded.dev>
Date: Mon, 18 Nov 2024 15:38:06 +0900
Subject: [PATCH] feat: propagate signals to launched subprocesses so that they
 can properly clean up resources

---
 command/cleanup.go | 39 ++++++++++++++++++++++++++++++++++++++-
 command/please.go  | 21 +++++++++++++++++++++
 2 files changed, 59 insertions(+), 1 deletion(-)

diff --git a/command/cleanup.go b/command/cleanup.go
index 2e84118..0f4af4a 100644
--- a/command/cleanup.go
+++ b/command/cleanup.go
@@ -7,8 +7,10 @@ import (
 	"log"
 	"os"
 	"os/exec"
+	"os/signal"
 	"strconv"
 	"strings"
+	"syscall"
 
 	"github.com/google/go-github/github"
 	cli "gopkg.in/urfave/cli.v1"
@@ -71,7 +73,24 @@ func CmdCleanup(c *cli.Context) (err error) {
 		cmd.Stdout = os.Stdout
 		cmd.Stderr = os.Stderr
 
+		signalChannel := make(chan os.Signal, 1)
+		signal.Notify(signalChannel, syscall.SIGINT, syscall.SIGTERM, syscall.SIGHUP)
+		go func() {
+			for sig := range signalChannel {
+				if cmd.Process != nil {
+					err := cmd.Process.Signal(sig)
+					if err != nil {
+						log.Printf("error sending signal to child process (%d): %s\n", cmd.Process.Pid, err)
+					}
+				} else {
+					// TODO: is this always the right thing to do if we're not running a subprocess?
+					os.Exit(1)
+				}
+			}
+		}()
+
 		err = cmd.Run()
+		signal.Stop(signalChannel)
 		if err != nil {
 			log.Println("undeploy error: ", err)
 
@@ -108,7 +127,25 @@ func listDeployedPullRequests(listScript string) ([]string, error) {
 	cmd := exec.Command(listScript)
 	cmd.Stdout = &stdout
 
-	if err := cmd.Run(); err != nil {
+	signalChannel := make(chan os.Signal, 1)
+	signal.Notify(signalChannel, syscall.SIGINT, syscall.SIGTERM, syscall.SIGHUP)
+	go func() {
+		for sig := range signalChannel {
+			if cmd.Process != nil {
+				err := cmd.Process.Signal(sig)
+				if err != nil {
+					log.Printf("error sending signal to child process (%d): %s\n", cmd.Process.Pid, err)
+				}
+			} else {
+				// TODO: is this always the right thing to do if we're not running a subprocess?
+				os.Exit(1)
+			}
+		}
+	}()
+
+	err := cmd.Run()
+	signal.Stop(signalChannel)
+	if err != nil {
 		return nil, err
 	}
 
diff --git a/command/please.go b/command/please.go
index 9c0932b..5d6e713 100644
--- a/command/please.go
+++ b/command/please.go
@@ -9,8 +9,10 @@ import (
 	"log"
 	"os"
 	"os/exec"
+	"os/signal"
 	"strconv"
 	"strings"
+	"syscall"
 
 	"github.com/google/go-github/github"
 	cli "gopkg.in/urfave/cli.v1"
@@ -151,6 +153,23 @@ func CmdPlease(c *cli.Context) (err error) {
 	}
 
 	// Start deploy script
+	signalChannel := make(chan os.Signal, 1)
+	signal.Notify(signalChannel, syscall.SIGINT, syscall.SIGTERM, syscall.SIGHUP)
+	go func() {
+		cmd := cmd
+		for sig := range signalChannel {
+			if cmd.Process != nil {
+				err := cmd.Process.Signal(sig)
+				if err != nil {
+					log.Printf("error sending signal to child process (%d): %s\n", cmd.Process.Pid, err)
+				}
+			} else {
+				// TODO: is this always the right thing to do if we're not running a subprocess?
+				os.Exit(1)
+			}
+		}
+	}()
+
 	err = cmd.Start()
 	if err != nil {
 		err2 := updateStatus(StateError, "")
@@ -169,6 +188,8 @@ func CmdPlease(c *cli.Context) (err error) {
 
 	// Wait on the deploy to finish
 	err = cmd.Wait()
+	signal.Stop(signalChannel)
+
 	if err != nil {
 		err2 := updateStatus(StateFailure, "")
 		if err2 != nil {