Successfully exported an image and attached the license. when I tried to created an image with the licensed_image.tar.gz, the operation failed with the error " - The size of the image inside the tar archive is larger than 100 Gb.".

After consulting the GCE team, finally decided to go over all the processes again without using the trusty-image we used for our build, instead, pick up a smaller image and attach the license. Expecting the new instance to support Cbuildbot. 

Created a test instance with the license imported. Tried to run Cbuildbot with VMTest, it turned out it required environment configured by buildbot steps, I made some tweaks, it failed in different places though.

will:
1) continue on working out the Cbuildbot.
2) learn manual vmtest steps suggested by Don.

Triggered a cbuildbot run and vmtest first failed with package_not_installed error. installed the packages and run vmtest individually (as cbuildbot has prepared all the prerequisites). Looks like vmtest passed:

nxia@kvm-test-6-builder:/mnt/tmp/buildroot/src/scripts$ bin/ctest '--board=cyan' '--type=vm' --no_graphics --verbose '--target_image=/mnt/tmp/buildroot/src/build/images/cyan/latest-cbuildbot/chromiumos_test_image.bin' '--test_results_root=/mnt/tmp/buildroot/chroot/tmp/cbuildbotrsua0_/test_harness' --only_verify '--suite=smoke' --whitelist_chrome_crashes '--ssh_private_key=/mnt/tmp/buildroot/src/build/images/cyan/latest-cbuildbot/id_rsa' 
2016/11/19 01:34:46 - ctest - INFO    : Could not find a latest image to use. Using target instead.
2016/11/19 01:34:46 - cros_build_lib.py - INFO    : RunCommand: /mnt/tmp/buildroot/src/platform/crostestutils/au_test_harness/cros_au_test_harness.py '--base_image=/mnt/tmp/buildroot/src/build/images/cyan/latest-cbuildbot/chromiumos_test_image.bin' '--target_image=/mnt/tmp/buildroot/src/build/images/cyan/latest-cbuildbot/chromiumos_test_image.bin' '--board=cyan' '--type=vm' '--remote=0.0.0.0' --verbose '--jobs=1' '--ssh_private_key=/mnt/tmp/buildroot/src/build/images/cyan/latest-cbuildbot/id_rsa' '--verify_suite_name=smoke' '--test_prefix=SimpleTestVerify' '--test_results_root=/mnt/tmp/buildroot/chroot/tmp/cbuildbotrsua0_/test_harness' --no_graphics --whitelist_chrome_crashes in /mnt/tmp/buildroot/src/scripts
2016/11/19 01:34:46 - cros_au_test_harness.py - INFO    : No update cache found. Update testing will not work.  Run  cros_generate_update_payloads if this was not intended.
2016/11/19 01:34:46 - cros_au_test_harness.py - INFO    : Running tests in test suite in parallel.
2016/11/19 01:36:30 - au_worker.py - INFO    : SimpleTestVerify: Copied shared disk image /mnt/tmp/buildroot/src/build/images/cyan/latest-cbuildbot/chromiumos_qemu_image.bin to /tmp/chromiumos_qemu_disk.bin.zHCQb_.
2016/11/19 01:36:30 - au_worker.py - INFO    : SimpleTestVerify: Running smoke suite to verify image.
INFO    : QEMU binary: /mnt/tmp/buildroot/chroot/usr/bin/qemu-system-x86_64
INFO    : QEMU version: QEMU emulator version 2.6.0, Copyright (c) 2003-2008 Fabrice Bellard
Stopping the KVM instance
.
----------------------------------------------------------------------
Ran 1 test in 1314.800s

OK

uploaded results to gs://kvm-bucket/vmtest_result.tar

The result logs look good to me. @dgarrett, Can you just confirm the tests passed without problems?

Sweet! That OK at the end is the sign of goodness.

The other way to check is the exit code (echo $?), which is what cbuildbot does.

 Issue 341900  has been merged into this issue.