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bosh-linux-stemcell-builder

Tools for creating stemcells.

Building a stemcell locally

First make sure you have a local copy of this repository. Additionally, you must download an external asset - VMware-ovftool-*.bundle. See External Assets for instructions on where to download it from. Please place that asset in ci/docker directory.

If you already have a stemcell-building environment set up and ready, skip to the Build Steps section. Otherwise, follow one of these two methods before trying to run the commands in Build Steps.

If you have docker installed,

host$ cd ci/docker
host$ ./run os-image-stemcell-builder

If you are not running on Linux or you do not have Docker installed, use vagrant to start a new VM which has Docker, and then change back into the ./docker directory...

host$ vagrant up
host$ vagrant ssh

Once you have Docker running, run ./run...

vagrant$ cd /opt/bosh/ci/docker
vagrant$ ./run os-image-stemcell-builder
container$ whoami
ubuntu

You're now ready to continue from the Build Steps section.

Troubleshooting: if you run into issues, try destroying any existing VM, update your box, and try again...

host$ vagrant destroy
host$ vagrant box update

Build Steps

At this point, you should be ssh'd and running within a docker container in the bosh-linux-stemcell-builder directory. Start by installing the latest dependencies before continuing to a specific build task...

$ echo $PWD
/opt/bosh
$ bundle install --local

If you receive an Bundle error you need to install the bundler version specified in the error message

$ gem install bundler -v 1.17.3
$ bundle install --local

Build an OS image

An OS image is a tarball that contains a snapshot of an entire OS filesystem that contains all the libraries and system utilities that the BOSH agent depends on. It does not contain the BOSH agent or the virtualization tools: there is a separate Rake task that adds the BOSH agent and a chosen set of virtualization tools to any base OS image, thereby producing a stemcell. The OS Image should be rebuilt when you are making changes to packages we install in the operating system, or when making changes to how we configure those packages, or if you need to pull in and test an updated package from upstream.

$ mkdir -p $PWD/tmp
$ bundle exec rake stemcell:build_os_image[ubuntu,xenial,$PWD/tmp/ubuntu_base_image.tgz]

The arguments to stemcell:build_os_image are:

  1. operating_system_name (ubuntu): identifies which type of OS to fetch. Determines which package repository and packaging tool will be used to download and assemble the files. Currently, only ubuntu is recognized.
  2. operating_system_version (xenial): an identifier that the system may use to decide which release of the OS to download. Acceptable values depend on the operating system. For ubuntu, use xenial.
  3. os_image_path ($PWD/tmp/ubuntu_base_image.tgz): the path to write the finished OS image tarball to. If a file exists at this path already, it will be overwritten without warning.

Building a Stemcell

The stemcell should be rebuilt when you are making and testing BOSH-specific changes on top of the base OS image such as new bosh-agent versions, or updating security configuration, or changing user settings.

$ mkdir -p $PWD/tmp
$ bundle exec rake stemcell:build_with_local_os_image[aws,xen,ubuntu,xenial,$PWD/tmp/ubuntu_base_image.tgz,"1.23"]

The arguments to stemcell:build_with_local_os_image are:

  1. infrastructure_name (aws): Which IAAS you are producing the stemcell for. Determines which virtualization tools to package on top of the stemcell.
  2. hypervisor_name (xen): Depending on what the IAAS supports, which hypervisor to target.
  3. operating_system_name (ubuntu): Type of OS. Same as stemcell:build_os_image
  4. operating_system_version (xenial): OS release. Same as stemcell:build_os_image
  5. os_image_path ($PWD/tmp/ubuntu_base_image.tgz): Path to base OS image produced in stemcell:build_os_image
  6. build_number (1.23): Stemcell version.

The final argument, which specifies the build number, is optional and will default to '0000'

Testing

How to run tests for OS Images

The OS tests are meant to be run against the OS environment to which they belong. When you run the stemcell:build_os_image rake task, it will create a .raw OS image that it runs the OS specific tests against. You will need to run the rake task the first time you create your docker container, but everytime after, as long as you do not destroy the container, you should be able to just run the specific tests.

To run the ubuntu_xenial_spec.rb tests for example you will need to:

  • bundle exec rake stemcell:build_os_image[ubuntu,xenial,$PWD/tmp/ubuntu_base_image.tgz]
  • -update tests-

Then run the following:

cd /opt/bosh/bosh-stemcell
OS_IMAGE=/opt/bosh/tmp/ubuntu_base_image.tgz bundle exec rspec -fd spec/os_image/ubuntu_xenial_spec.rb

How to run tests for Stemcell

When you run the stemcell:build_with_local_os_image or stemcell:build rake task, it will create a stemcell that it runs the stemcell specific tests against. You will need to run the rake task the first time you create your docker container, but everytime after, as long as you do not destroy the container, you should be able to just run the specific tests.

To run the stemcell tests when building against local OS image you will need to:

  • bundle exec rake stemcell:build_with_local_os_image[aws,xen,ubuntu,xenial,$PWD/tmp/ubuntu_base_image.tgz]
  • -make test changes-

Then run the following:

    $ cd /opt/bosh/bosh-stemcell; \
    STEMCELL_IMAGE=/mnt/stemcells/aws/xen/ubuntu/work/work/aws-xen-ubuntu.raw \
    STEMCELL_WORKDIR=/mnt/stemcells/aws/xen/ubuntu/work/work/chroot \
    OS_NAME=ubuntu \
    bundle exec rspec -fd --tag ~exclude_on_aws \
    spec/os_image/ubuntu_xenial_spec.rb \
    spec/stemcells/ubuntu_xenial_spec.rb \
    spec/stemcells/go_agent_spec.rb \
    spec/stemcells/aws_spec.rb \
    spec/stemcells/stig_spec.rb \
    spec/stemcells/cis_spec.rb

ShelloutTypes

In pursuit of more robustly testing, we wrote our testing library for stemcell contents, called ShelloutTypes.

The ShelloutTypes code has its own unit tests, but require root privileges and an ubuntu chroot environment to run. For this reason, we use the bosh/main-ubuntu-chroot docker imagefor unit tests. To run these unit tests locally, run:

$ docker run bosh/main-ubuntu-chroot    # now in /opt/bosh
$ source /etc/profile.d/chruby.sh
$ chruby 2.3.1

$ #create user for ShelloutTypes::File tests
$ chroot /tmp/ubuntu-chroot /bin/bash -c 'useradd -G nogroup shellout'

$ bundle install --local
$ cd bosh-stemcell
$ bundle exec rspec spec/ --tag shellout_types

The above strategy is derived from our CI unit testing job's script.

Troubleshooting

If you find yourself debugging any of the above processes, here is what you need to know:

  1. Most of the action happens in Bash scripts, which are referred to as stages, and can be found in stemcell_builder/stages/<stage_name>/apply.sh.

  2. While debugging a particular stage that is failing, you can resume the process from that stage by adding resume_from=<stage_name> to the end of your bundle exec rake command. When a stage's apply.sh fails, you should see a message of the form Can't find stage '<stage>' to resume from. Aborting. so you know which stage failed and where you can resume from after fixing the problem. Please use caution as stages are not guaranteed to be idempotent.

    Example usage:

    $ bundle exec rake stemcell:build_os_image[ubuntu,xenial,$PWD/tmp/ubuntu_base_image.tgz] resume_from=rsyslog_config

  3. Directory renamed before its status could be extracted

    If you run into the following error whilst builing an image with Docker:

    ubuntu@98b2a2aed0e6:/opt/bosh$ bundle exec rake stemcell:build_with_local_os_image[vsphere,esxi,ubuntu,xenial,$PWD/tmp/ubuntu_base_image.tgz,705]
cd /opt/bosh/bosh-stemcell; OS_IMAGE=/opt/bosh/tmp/ubuntu_base_image.tgz bundle exec rspec -fd spec/os_image/ubuntu_xenial_spec.rb
All stemcell_tarball tests are being skipped. STEMCELL_WORKDIR needs to be set
All stemcell_image tests are being skipped. STEMCELL_IMAGE needs to be set
Run options: exclude {:stemcell_image=>true, :stemcell_tarball=>true, :shellout_types=>true}

Ubuntu 16.04 OS image
tar: ./var/log: Directory renamed before its status could be extracted

    You can convert Docker's storage driver to aufs as described here.

Pro Tips

  • If the OS image has been built and so long as you only make test case modifications you can just rerun the tests (without rebuilding OS image). Details in section How to run tests for OS Images
  • If the Stemcell has been built and you are only updating tests, you do not need to re-build the stemcell. You can simply rerun the tests (without rebuilding Stemcell. Details in section How to run tests for Stemcell
  • It's possible to verify OS/Stemcell changes without making a deployment using the stemcell. For an AWS specific ubuntu stemcell, the filesytem is available at /mnt/stemcells/aws/xen/ubuntu/work/work/chroot

External Assets

The ovftool installer from VMWare can be found at my.vmware.com.

The ovftool installer must be copied into the ci/docker/os-image-stemcell-builder next to the Dockerfile or you will receive the error

Step 24/30 : ADD ${OVF_TOOL_INSTALLER} /tmp/ovftool_installer.bundle
ADD failed: stat /var/lib/docker/tmp/docker-builder389354746/VMware-ovftool-4.1.0-2459827-lin.x86_64.bundle: no such file or directory

Rebuilding the docker image

The Docker image is published to bosh/os-image-stemcell-builder. You will need the ovftool installer present on your filesystem.

Rebuild the container with the build script...

vagrant$ ./build os-image-stemcell-builder

When ready, push to DockerHub and use the credentials from LastPass...

vagrant$ cd os-image-stemcell-builder
vagrant$ ./push