================================================== `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 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 and then run:: ./bootstrap You can run Teuthology's internal unit tests with:: ./virtualenv/bin/nosetests 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: - 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. You need to be able to SSH in to the listed targets without passphrases, and the remote user needs to have passphraseless `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. * ``ceph``: Bring up Ceph * ``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...) * ``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 ``/tmp/cephtest/{rundir}``. The ``{rundir}`` is the name of the run (as given by ``--name``) or if no name is specified, ``user@host-timestamp`` is used. To change the location of the sandbox directory, the following options can be specified in ``$HOME/.teuthology.yaml``:: base_test_dir: The ``base_test_dir`` option will set the base directory to use for the individual run directories. If not specified, this defaults to: ``/tmp/cephtest``. test_path: The ``test_path`` option will set the complete path to use for the test directory. This allows for the old behavior, where ``/tmp/cephtest`` was used as the sandbox 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