Cancel actions on process interrupts

cmd/weatherreporter/main.go

@@ -3,14 +3,23 @@ package main
 import (
 	"context"
 	"fmt"
+	"io"
 	"os"
+	"os/signal"
+	"syscall"
 
 	"gitea.maximumdirect.net/eric/weatherreporter/internal/cli"
 )
 
 func main() {
-	if err := cli.Run(context.Background(), os.Args[1:], os.Stdout, os.Stderr); err != nil {
+	if err := runCommand(os.Args[1:], os.Stdout, os.Stderr, cli.Run); err != nil {
 		fmt.Fprintf(os.Stderr, "weatherreporter: %v\n", err)
 		os.Exit(1)
 	}
 }
+
+func runCommand(args []string, stdout, stderr io.Writer, runner func(context.Context, []string, io.Writer, io.Writer) error) error {
+	ctx, stop := signal.NotifyContext(context.Background(), os.Interrupt, syscall.SIGTERM)
+	defer stop()
+	return runner(ctx, args, stdout, stderr)
+}

cmd/weatherreporter/main_test.go

@@ -0,0 +1,56 @@
+package main
+
+import (
+	"context"
+	"errors"
+	"io"
+	"os"
+	"syscall"
+	"testing"
+	"time"
+)
+
+func TestRunCommandCancelsActionContextOnSignal(t *testing.T) {
+	for _, tt := range []struct {
+		name   string
+		signal os.Signal
+	}{
+		{name: "Interrupt", signal: os.Interrupt},
+		{name: "Terminate", signal: syscall.SIGTERM},
+	} {
+		t.Run(tt.name, func(t *testing.T) {
+			started := make(chan struct{})
+			done := make(chan error, 1)
+			go func() {
+				done <- runCommand(nil, io.Discard, io.Discard, func(ctx context.Context, _ []string, _, _ io.Writer) error {
+					close(started)
+					<-ctx.Done()
+					return ctx.Err()
+				})
+			}()
+
+			select {
+			case <-started:
+			case <-time.After(time.Second):
+				t.Fatal("runner did not receive an action context")
+			}
+
+			process, err := os.FindProcess(os.Getpid())
+			if err != nil {
+				t.Fatalf("FindProcess() error = %v", err)
+			}
+			if err := process.Signal(tt.signal); err != nil {
+				t.Fatalf("Signal(%v) error = %v", tt.signal, err)
+			}
+
+			select {
+			case err := <-done:
+				if !errors.Is(err, context.Canceled) {
+					t.Fatalf("runCommand() error = %v, want context cancellation", err)
+				}
+			case <-time.After(time.Second):
+				t.Fatal("interrupt did not cancel the action context")
+			}
+		})
+	}
+}