From 9badd05327bc3a1a96c828de3c32dc8101be77cc Mon Sep 17 00:00:00 2001
From: Dmitry Vyukov <dvyukov@google.com>
Date: Sun, 19 Nov 2017 12:29:00 +0100
Subject: vm/gce: provide VM console output on boot failures

"can't ssh into the instance" is not a very useful error.
---
 pkg/gce/gce.go | 10 ++++++++++
 vm/gce/gce.go  |  4 ++++
 2 files changed, 14 insertions(+)

diff --git a/pkg/gce/gce.go b/pkg/gce/gce.go
index e8ad084e6..c08ae5519 100644
--- a/pkg/gce/gce.go
+++ b/pkg/gce/gce.go
@@ -228,6 +228,16 @@ func (ctx *Context) DeleteImage(imageName string) error {
 	return nil
 }
 
+func (ctx *Context) GetSerialPortOutput(instance string) (string, error) {
+	<-ctx.apiRateGate
+	output, err := ctx.computeService.Instances.GetSerialPortOutput(
+		ctx.ProjectID, ctx.ZoneID, instance).Port(1).Do()
+	if err != nil {
+		return "", fmt.Errorf("failed to get serial port output: %v", err)
+	}
+	return output.Contents, nil
+}
+
 type resourcePoolExhaustedError string
 
 func (err resourcePoolExhaustedError) Error() string {
diff --git a/vm/gce/gce.go b/vm/gce/gce.go
index 165ffe4ce..7d973fe2e 100644
--- a/vm/gce/gce.go
+++ b/vm/gce/gce.go
@@ -15,6 +15,7 @@ import (
 	"archive/tar"
 	"bytes"
 	"compress/gzip"
+	"errors"
 	"fmt"
 	"io"
 	"io/ioutil"
@@ -164,6 +165,9 @@ func (pool *Pool) Create(workdir string, index int) (vmimpl.Instance, error) {
 	}
 	Logf(0, "wait instance to boot: %v (%v)", name, ip)
 	if err := pool.waitInstanceBoot(ip, sshKey, sshUser); err != nil {
+		if output, err := pool.GCE.GetSerialPortOutput(name); err == nil {
+			err = errors.New(err.Error() + "\n\n" + output)
+		}
 		return nil, err
 	}
 	ok = true
-- 
cgit mrf-deployment