[BUGFIX] Properly detect failure to launch process

haproxy/haproxy_cmd/cmd.go

@@ -24,6 +24,10 @@ func runCommand(sd *lib.Shutdown, cmdPath string, args ...string) (*exec.Cmd, er
 		sd.Done()
 		return nil, errors.Wrapf(err, "error starting %s", file)
 	}
+	if cmd.Process == nil {
+		sd.Done()
+		return nil, errors.Wrapf(err, "Process '%s' could not be started", file)
+	}
 	exited := uint32(0)
 	go func() {
 		defer sd.Done()

haproxy/haproxy_cmd/cmd_test.go

@@ -0,0 +1,25 @@
+package haproxy_cmd
+
+import (
+	"testing"
+
+	"github.com/criteo/haproxy-consul-connect/lib"
+	"github.com/stretchr/testify/assert"
+)
+
+func Test_runCommand_ok(t *testing.T) {
+	t.Parallel()
+	sd := lib.NewShutdown()
+	cmd, err := runCommand(sd, "ls", ".")
+	assert.NoError(t, err)
+	cmd.Wait()
+}
+
+func Test_runCommand_nok_wrong_path(t *testing.T) {
+	t.Parallel()
+	sd := lib.NewShutdown()
+	cmd, err := runCommand(sd, "/path/to/nowhere/that/can/be/found/myExec", "--help")
+	assert.NotNil(t, err)
+	assert.Contains(t, err.Error(), "no such file or directory")
+	assert.Nil(t, cmd)
+}

haproxy/haproxy_cmd/run.go

@@ -4,6 +4,7 @@ import (
 	"fmt"
 	"net"
 	"net/http"
+	"os"
 	"time"
 
 	"github.com/criteo/haproxy-consul-connect/haproxy/dataplane"
@@ -29,8 +30,11 @@ func Start(sd *lib.Shutdown, cfg Config) (*dataplane.Dataplane, error) {
 	if err != nil {
 		return nil, err
 	}
+	if haCmd.Process == nil {
+		return nil, fmt.Errorf("%s was not started", cfg.HAProxyPath)
+	}
 
-	_, err = runCommand(sd,
+	cmd, err := runCommand(sd,
 		cfg.DataplanePath,
 		"--scheme", "unix",
 		"--socket-path", cfg.DataplaneSock,
@@ -41,9 +45,17 @@ func Start(sd *lib.Shutdown, cfg Config) (*dataplane.Dataplane, error) {
 		"--userlist", "controller",
 		"--transaction-dir", cfg.DataplaneTransactionDir,
 	)
+	cleanupHAProxy := func() {
+		haCmd.Process.Signal(os.Kill)
+	}
 	if err != nil {
+		cleanupHAProxy()
 		return nil, err
 	}
+	if cmd.Process == nil {
+		cleanupHAProxy()
+		return nil, fmt.Errorf("%s failed to start", cfg.DataplanePath)
+	}
 
 	dataplaneClient := dataplane.New(
 		"http://unix-sock",