enter: start default services before executing subcommand

internals/cli/cmd_enter_test.go

@@ -19,6 +19,7 @@ import (
 	"path/filepath"
 	"strings"
 	"text/template"
+	"time"
 
 	. "gopkg.in/check.v1"
 
@@ -241,3 +242,38 @@ func (s *PebbleSuite) TestEnterHelpCommandHelpArg(c *C) {
 	c.Check(stdout, Matches, "(?s).*\\bThe help command displays information about commands\\..*")
 	c.Check(exitCode, Equals, 0)
 }
+
+// TestEnterSubCommandWaits checks that the subcommand in enter
+// starts **after** the default services have started.
+func (s *PebbleSuite) TestEnterSubCommandWaits(c *C) {
+	layerTemplate := dumbDedent(`
+		services:
+		  stat:
+		    override: replace
+		    command: /bin/sh -c 'date --rfc-3339=ns > $PEBBLE/enter-wait; sleep 1;'
+		    startup: enabled
+	`)
+	layerPath := filepath.Join(s.pebbleDir, "layers", "001-stat.yaml")
+	writeTemplate(layerPath, layerTemplate, nil)
+
+	cmd := []string{"pebble", "enter", "--run", "exec", "date", "--rfc-3339=ns"}
+	restore := fakeArgs(cmd...)
+	defer restore()
+
+	exitCode := cli.PebbleMain()
+	c.Check(exitCode, Equals, 0)
+	// stderr is written to stdout buffer because of "combine stderr" mode,
+	// see cmd/pebble/cmd_exec.go:163
+	c.Check(s.Stderr(), Equals, "")
+	stdout := s.Stdout()
+
+	svcOut, err := os.ReadFile(filepath.Join(s.pebbleDir, "enter-wait"))
+	c.Check(err, IsNil)
+
+	layout := "2006-01-02 15:04:05.000000000-07:00"
+	subCmdExecTime, err := time.Parse(layout, strings.TrimSpace(stdout))
+	c.Check(err, IsNil)
+	svcStartTime, err := time.Parse(layout, strings.TrimSpace(string(svcOut)))
+	c.Check(err, IsNil)
+	c.Check(svcStartTime.Before(subCmdExecTime), Equals, true)
+}

internals/cli/cmd_run.go

@@ -229,21 +229,40 @@ func runDaemon(rcmd *cmdRun, ch chan os.Signal, ready chan<- func()) (err error)
 
 	logger.Debugf("activation done in %v", time.Now().Truncate(time.Millisecond).Sub(t0))
 
+	// The "stop" channel is used by the "enter" command to stop the daemon.
+	var stop chan struct{}
+	if ready != nil {
+		stop = make(chan struct{}, 1)
+	}
+	notifyReady := func() {
+		ready <- func() { close(stop) }
+		close(ready)
+	}
+
 	if !rcmd.Hold {
+		// Start the default services (those configured with startup: enabled).
 		servopts := client.ServiceOptions{}
 		changeID, err := rcmd.client.AutoStart(&servopts)
 		if err != nil {
 			logger.Noticef("Cannot start default services: %v", err)
 		} else {
-			logger.Noticef("Started default services with change %s.", changeID)
+			// Wait for the default services to actually start and then notify
+			// the ready channel (for the "enter" command).
+			go func() {
+				logger.Debugf("Waiting for default services to autostart with change %s.", changeID)
+				_, err := rcmd.client.WaitChange(changeID, nil)
+				if err != nil {
+					logger.Noticef("Cannot wait for autostart change %s: %v", changeID, err)
+				} else {
+					logger.Noticef("Started default services with change %s.", changeID)
+				}
+				if ready != nil {
+					notifyReady()
+				}
+			}()
 		}
-	}
-
-	var stop chan struct{}
-	if ready != nil {
-		stop = make(chan struct{}, 1)
-		ready <- func() { close(stop) }
-		close(ready)
+	} else if ready != nil {
+		notifyReady()
 	}
 
 out: