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Teuthology -- The Ceph integration test runner

The Ceph project needs automated tests. Because Ceph is a highly distributed system, and has active kernel development, its testing requirements are quite different from e.g. typical LAMP web applications. Nothing out there seemed to handle our requirements, so we wrote our own framework, called Teuthology.

Overview

Teuthology runs a given set of Python functions (tasks), with an SSH connection to every host participating in the test. The SSH connection uses Paramiko, a native Python client for the SSH2 protocol, and this allows us to e.g. run multiple commands inside a single SSH connection, to speed up test execution. Tests can use gevent to perform actions concurrently or in the background.

Build

Teuthology is not meant to be distributed as a library, therefore we depend on the pinned dependencies listed in requirements.txt, the setup.py will not list any and will only be there to install the package entry points (a.k.a teuthology's scripts).

Bootstrap for Ubuntu Systems

A boostrap script is provided for automated builds/execution of teuthology itself. You can run it directly only if you are using Ubuntu.

Teuthology uses several Python packages that are not in the standard library. To make the dependencies easier to get right, we use a virtualenv to manage them. To get started, ensure you have the virtualenv and pip programs installed; e.g. on Debian/Ubuntu:

sudo apt-get install python-dev python-virtualenv python-pip libevent-dev libmysqlclient-dev python-libvirt

and then run:

./bootstrap

MacOS X

Note

These instructions assume you are using homebrew

As always, create a virtualenv specific to teuthology and make sure it is activated before proceeding (location doesn't matter, we use an example location):

mkdir ~/.virtualenvs
virtualenv --system-site-packages ~/.virtualenvs/teuthology
source ~/.virtualenvs/teuthology/bin/activate

Install the system dependencies:

brew install libvirt mysql libevent

Make sure you are able to import libvirt without error:

python -c "import libvirt"

If python can't find libvirt yet, you may need to do the following:

cd /Library/Python/{pyversion}/site-packages sudo ln -s /usr/local/Cellar/libvirt/{version}/lib/python{pyversion}/site-packages/* .

Finally, install the teuthology package and requirements.txt:

python setup.py develop
pip install -r requirements.txt

Generic install

These instructions should help get teuthology installed properly in a system that is not OSX or Debian-based.

Install all the system dependencies needed:

  • mysql client
  • libevent
  • libvirt (with the Python bindings)

Install Python packaging tools:

  • pip
  • virtualenv

In some cases, depending on the OS, you will need a python development package with some build helpers that are required to build packages. In Ubuntu, this is the python-dev package.

With a dedicated virtualenv activated, install the teuthology package and requirements.txt:

python setup.py develop
pip install -r requirements.txt

Test configuration

An integration test run takes three items of configuration:

  • targets: what hosts to run on; this is a dictionary mapping hosts to ssh host keys, like: "username@hostname.example.com: ssh-rsa long_hostkey_here"
  • roles: how to use the hosts; this is a list of lists, where each entry lists all the roles to be run on a single host; for example, a single entry might say [mon.1, osd.1]
  • tasks: how to set up the cluster and what tests to run on it; see below for examples

The format for this configuration is YAML, a structured data format that is still human-readable and editable.

For example, a full config for a test run that sets up a three-machine cluster, mounts Ceph via ceph-fuse, and leaves you at an interactive Python prompt for manual exploration (and enabling you to SSH in to the nodes & use the live cluster ad hoc), might look like this:

roles:
- [mon.0, mds.0, osd.0]
- [mon.1, osd.1]
- [mon.2, client.0]
targets:
    ubuntu@host07.example.com: ssh-rsa host07_ssh_key
    ubuntu@host08.example.com: ssh-rsa host08_ssh_key
    ubuntu@host09.example.com: ssh-rsa host09_ssh_key
tasks:
- install:
- ceph:
- ceph-fuse: [client.0]
- interactive:

The number of entries under roles and targets must match.

Note the colon after every task name in the tasks section.

The install task needs to precede all other tasks.

The listed targets need resolvable hostnames. If you do not have a DNS server running, you can add entries to /etc/hosts. You also need to be able to SSH in to the listed targets without passphrases, and the remote user needs to have passwordless sudo access. Note that the ssh keys at the end of the targets entries are the public ssh keys for the hosts. On Ubuntu, these are located at /etc/ssh/ssh_host_rsa_key.pub

If you'd save the above file as example.yaml, you could run teuthology on it by saying:

./virtualenv/bin/teuthology example.yaml

You can also pass the -v option, for more verbose execution. See teuthology --help for more.

Multiple config files

You can pass multiple files as arguments to teuthology. Each one will be read as a config file, and their contents will be merged. This allows you to e.g. share definitions of what a "simple 3 node cluster" is. The source tree comes with roles/3-simple.yaml, so we could skip the roles section in the above example.yaml and then run:

./virtualenv/bin/teuthology roles/3-simple.yaml example.yaml

Reserving target machines

Before locking machines will work, you must create a .teuthology.yaml file in your home directory that sets a lock_server, i.e.:

lock_server: http://host.example.com:8080/lock

Teuthology automatically locks nodes for you if you specify the --lock option. Without this option, you must specify machines to run on in a targets.yaml file, and lock them using teuthology-lock.

Note that the default owner of a machine is USER@HOST. You can override this with the --owner option when running teuthology or teuthology-lock.

With teuthology-lock, you can also add a description, so you can remember which tests you were running on them. This can be done when locking or unlocking machines, or as a separate action with the --update option. To lock 3 machines and set a description, run:

./virtualenv/bin/teuthology-lock --lock-many 3 --desc 'test foo'

If machines become unusable for some reason, you can mark them down:

./virtualenv/bin/teuthology-lock --update --status down machine1 machine2

To see the status of all machines, use the --list option. This can be restricted to particular machines as well:

./virtualenv/bin/teuthology-lock --list machine1 machine2

Tasks

A task is a Python module in the teuthology.task package, with a callable named task. It gets the following arguments:

  • ctx: a context that is available through the lifetime of the test run, and has useful attributes such as cluster, letting the task access the remote hosts. Tasks can also store their internal state here. (TODO beware namespace collisions.)
  • config: the data structure after the colon in the config file, e.g. for the above ceph-fuse example, it would be a list like ["client.0"].

Tasks can be simple functions, called once in the order they are listed in tasks. But sometimes, it makes sense for a task to be able to clean up after itself; for example, unmounting the filesystem after a test run. A task callable that returns a Python context manager will have the manager added to a stack, and the stack will be unwound at the end of the run. This means the cleanup actions are run in reverse order, both on success and failure. A nice way of writing context managers is the contextlib.contextmanager decorator; look for that string in the existing tasks to see examples, and note where they use yield.

Further details on some of the more complex tasks such as install or workunit can be obtained via python help. For example:

>>> import teuthology.task.workunit
>>> help(teuthology.task.workunit)

displays a page of more documentation and more concrete examples.

Some of the more important / commonly used tasks include:

  • chef: Run the chef task.
  • install: by default, the install task goes to gitbuilder and installs the results of the latest build. You can, however, add additional parameters to the test configuration to cause it to install any branch, SHA, archive or URL. The following are valid parameters.
  • branch: specify a branch (bobtail, cuttlefish...)
  • flavor: specify a flavor (next, unstable...). Flavors can be thought of as subsets of branches. Sometimes (unstable, for example) they may have a predefined meaning.
  • project: specify a project (ceph, samba...)
  • sha1: install the build with this sha1 value.
  • tag: specify a tag/identifying text for this build (v47.2, v48.1...)

  • ceph: Bring up Ceph

  • overrides: override behavior. Typically, this includes sub-tasks being overridden. Sub-tasks can nest further information. For example, overrides of install tasks are project specific, so the following section of a yaml file would cause all ceph installation to default into using the cuttlefish branch:

    overrides:
  install:
    ceph:
      branch: cuttlefish

  • workunit: workunits are a way of grouping tasks and behavior on targets.

  • sequential: group the sub-tasks into a unit where the sub-tasks run sequentially as listed.

  • parallel: group the sub-tasks into a unit where the sub-task all run in parallel.

Sequential and parallel tasks can be nested. Tasks run sequentially if not specified.

The above list is a very incomplete description of the tasks available on teuthology. The teuthology/task subdirectory contains all the python files that implement tasks. Many of these tasks are used to run shell scripts that are defined in the ceph/ceph-qa-suite.

Troubleshooting

Sometimes when a bug triggers, instead of automatic cleanup, you want to explore the system as is. Adding a top-level:

interactive-on-error: true

as a config file for teuthology will make that possible. With that option, any task that fails, will have the interactive task called after it. This means that before any cleanup happens, you get a chance to inspect the system -- both through Teuthology and via extra SSH connections -- and the cleanup completes only when you choose so. Just exit the interactive Python session to continue the cleanup.

Note that this only catches exceptions between the tasks. If a task calls multiple subtasks, e.g. with contextutil.nested, those cleanups will be performed. Later on, we can let tasks communicate the subtasks they wish to invoke to the top-level runner, avoiding this issue.

Test Sandbox Directory

Teuthology currently places most test files and mount points in a sandbox directory, defaulting to /home/$USER/cephtest. To change the location of the sandbox directory, the following option can be specified in $HOME/.teuthology.yaml:

test_path: <directory>

VIRTUAL MACHINE SUPPORT

Teuthology also supports virtual machines, which can function like physical machines but differ in the following ways:

VPSHOST:

A new entry, vpshost, has been added to the teuthology database of available machines. For physical machines, this value is null. For virtual machines, this entry is the name of the physical machine that that virtual machine resides on.

There are fixed "slots" for virtual machines that appear in the teuthology database. These slots have a machine type of vps and can be locked like any other machine. The existence of a vpshost field is how teuthology knows whether or not a database entry represents a physical or a virtual machine.

The following needs to be set in ~/.libvirt/libvirt.conf in order to get the right virtual machine associations for the Inktank lab:

uri_aliases = [
    'mira001=qemu+ssh://ubuntu@mira001.front.sepia.ceph.com/system?no_tty',
    'mira003=qemu+ssh://ubuntu@mira003.front.sepia.ceph.com/system?no_tty',
    'mira004=qemu+ssh://ubuntu@mira004.front.sepia.ceph.com/system?no_tty',
    'mira006=qemu+ssh://ubuntu@mira006.front.sepia.ceph.com/system?no_tty',
    'mira007=qemu+ssh://ubuntu@mira007.front.sepia.ceph.com/system?no_tty',
    'mira008=qemu+ssh://ubuntu@mira008.front.sepia.ceph.com/system?no_tty',
    'mira009=qemu+ssh://ubuntu@mira009.front.sepia.ceph.com/system?no_tty',
    'mira010=qemu+ssh://ubuntu@mira010.front.sepia.ceph.com/system?no_tty',
    'mira011=qemu+ssh://ubuntu@mira011.front.sepia.ceph.com/system?no_tty',
    'mira013=qemu+ssh://ubuntu@mira013.front.sepia.ceph.com/system?no_tty',
    'mira014=qemu+ssh://ubuntu@mira014.front.sepia.ceph.com/system?no_tty',
    'mira015=qemu+ssh://ubuntu@mira015.front.sepia.ceph.com/system?no_tty',
    'mira017=qemu+ssh://ubuntu@mira017.front.sepia.ceph.com/system?no_tty',
    'mira018=qemu+ssh://ubuntu@mira018.front.sepia.ceph.com/system?no_tty',
    'mira020=qemu+ssh://ubuntu@mira020.front.sepia.ceph.com/system?no_tty',
    'vercoi01=qemu+ssh://ubuntu@vercoi01.front.sepia.ceph.com/system?no_tty',
    'vercoi02=qemu+ssh://ubuntu@vercoi02.front.sepia.ceph.com/system?no_tty',
    'vercoi03=qemu+ssh://ubuntu@vercoi03.front.sepia.ceph.com/system?no_tty',
    'vercoi04=qemu+ssh://ubuntu@vercoi04.front.sepia.ceph.com/system?no_tty',
    'vercoi05=qemu+ssh://ubuntu@vercoi05.front.sepia.ceph.com/system?no_tty',
    'vercoi06=qemu+ssh://ubuntu@vercoi06.front.sepia.ceph.com/system?no_tty',
    'vercoi07=qemu+ssh://ubuntu@vercoi07.front.sepia.ceph.com/system?no_tty',
    'vercoi08=qemu+ssh://ubuntu@vercoi08.front.sepia.ceph.com/system?no_tty',
    'senta01=qemu+ssh://ubuntu@senta01.front.sepia.ceph.com/system?no_tty',
    'senta02=qemu+ssh://ubuntu@senta02.front.sepia.ceph.com/system?no_tty',
    'senta03=qemu+ssh://ubuntu@senta03.front.sepia.ceph.com/system?no_tty',
    'senta04=qemu+ssh://ubuntu@senta04.front.sepia.ceph.com/system?no_tty',
]

DOWNBURST:

When a virtual machine is locked, downburst is run on that machine to install a new image. This allows the user to set different virtual OSes to be installed on the newly created virtual machine. Currently the default virtual machine is ubuntu (precise). A different vm installation can be set using the --os-type option in teuthology.lock.

When a virtual machine is unlocked, downburst destroys the image on the machine.

Temporary yaml files are used to downburst a virtual machine. A typical yaml file will look like this:

downburst:
  cpus: 1
  disk-size: 30G
  distro: centos
  networks:
  - {source: front}
  ram: 4G

These values are used by downburst to create the virtual machine.

HOST KEYS:

Because teuthology reinstalls a new machine, a new hostkey is generated. After locking, once a connection is established to the new machine, teuthology-lock with the --list or --list-targets options will display the new keys. When vps machines are locked using the --lock-many option, a message is displayed indicating that --list-targets should be run later.

CEPH-QA-CHEF:

Once teuthology starts after a new vm is installed, teuthology checks for the existence of /ceph-qa-ready. If this file is not present, ceph-qa-chef is run when teuthology first comes up.

ASSUMPTIONS:

It is assumed that downburst is on the user's $PATH.

Test Suites

Most of the current teuthology test suite execution scripts automatically download their tests from the master branch of the appropriate github repository. People who want to run experimental test suites usually modify the download method in the teuthology/task script to use some other branch or repository. This should be generalized in later teuthology releases. Teuthology QA suites can be found in src/ceph-qa-suite. Make sure that this directory exists in your source tree before running the test suites.

Each suite name is determined by the name of the directory in ceph-qa-suite that contains that suite. The directory contains subdirectories and yaml files, which, when assembled, produce valid tests that can be run. The test suite application generates combinations of these files and thus ends up running a set of tests based off the data in the directory for the suite.

To run a suite, enter:

./schedule_suite.sh <suite> <ceph> <kernel> <email> <flavor> <teuth> <mtype> <template>

where:

  • suite: the name of the suite (the directory in ceph-qa-suite).
  • ceph: ceph branch to be used.
  • kernel: version of the kernel to be used.
  • email: email address to send the results to.
  • flavor: flavor of the test
  • teuth: version of teuthology to run
  • mtype: machine type of the run
  • templates: template file used for further modifying the suite (optional)

For example, consider:

schedule_suite.sh rbd wip-fix cuttlefish bob.smith@foo.com master cuttlefish plana

The above command runs the rbd suite using wip-fix as the ceph branch, a straight cuttlefish kernel, and the master flavor of cuttlefish teuthology. It will run on plana machines.

In order for a queued task to be run, a teuthworker thread on teuthology.front.sepia.ceph.com needs to remove the task from the queue. On teuthology.front.sepia.ceph.com, run ps aux | grep teuthology-worker to view currently running tasks. If no processes are reading from the test version that you are running, additonal teuthworker tasks need to be started. To start these tasks: * copy your build tree to /home/teuthworker on teuthology.front.sepia.ceph.com. * Give it a unique name (in this example, xxx) * start up some number of worker threads (as many as machines you are

testing with, there are 60 running for the default queue):

/home/virtualenv/bin/python /var/lib/teuthworker/xxx/virtualenv/bin/teuthworker /var/lib/teuthworker/archive --tube xxx --log-dir /var/lib/teuthworker/archive/worker_logs

Note: The threads on teuthology.front.sepia.ceph.com are started via ~/teuthworker/start.sh. You can use that file as a model for your own threads, or add to this file if you want your threads to be more permanent.

Once the suite completes, an email message is sent to the users specified, and a large amount of information is left on teuthology.front.sepia.ceph.com in /var/lib/teuthworker/archive.

This is symbolically linked to /a for convenience. A new directory is created whose name consists of a concatenation of the date and time that the suite was started, the name of the suite, the ceph branch tested, the kernel used, and the flavor. For every test run there is a directory whose name is the pid number of the pid of that test. Each of these directory contains a copy of the teuthology.log for that process. Other information from the suite is stored in files in the directory, and task-specific yaml files and other logs are saved in the subdirectories.

These logs are also publically available at http://qa-proxy.ceph.com/teuthology/.