CTS thoroughly exercises a pacemaker test cluster by running a randomized series of predefined tests on the cluster. CTS can be run against a pre-existing cluster configuration or (more typically) overwrite the existing configuration with a test configuration.
Three or more machines (one test exerciser and two or more test cluster machines).
The test cluster machines should be on the same subnet and have journalling filesystems (ext3, ext4, xfs, etc.) for all of their filesystems other than /boot. You also need a number of free IP addresses on that subnet if you intend to test mutual IP address takeover.
The test exerciser machine doesn't need to be on the same subnet as the test cluster machines. Minimal demands are made on the exerciser machine - it just has to stay up during the tests.
It helps a lot in tracking problems if all machines' clocks are closely synchronized. NTP does this automatically, but you can do it by hand if you want.
The exerciser needs to be able to ssh over to the cluster nodes as root without a password challenge. Configure ssh accordingly (see the Mini-HOWTO at the end of this document for more details).
The exerciser needs to be able to resolve the machine names of the test cluster - either by DNS or by /etc/hosts.
CTS is not guaranteed to run on all platforms that pacemaker itself does. It calls commands such as service that may not be provided by all OSes.
Install Pacemaker (including CTS) on all machines. These scripts are coordinated with particular versions of Pacemaker, so you need the same version of CTS as the rest of Pacemaker, and you need the same version of pacemaker and CTS on both the test exerciser and the test cluster machines.
You can install CTS from source, although many distributions provide packages that include it (e.g. pacemaker-cts or pacemaker-dev). Typically, packages will install CTS as /usr/share/pacemaker/tests/cts.
Configure cluster communications (Corosync, CMAN or Heartbeat) on the cluster machines and verify everything works.
NOTE: Do not run the cluster on the test exerciser machine.
NOTE: Wherever machine names are mentioned in these configuration files, they must match the machines' uname -n name. This may or may not match the machines' FQDN (fully qualified domain name) - it depends on how you (and your OS) have named the machines.
Now assuming you did all this, what you need to do is run CTSlab.py:
python ./CTSlab.py [options] number-of-tests-to-run
You must specify which nodes are part of the cluster with --nodes, e.g.:
--node "pcmk-1 pcmk-2 pcmk-3"
Most people will want to save the output with --outputfile, e.g.:
--outputfile ~/cts.log
Unless you want to test your pre-existing cluster configuration, you also want:
--clobber-cib --populate-resources --test-ip-base $IP # e.g. --test-ip-base 192.168.9.100
and configure some sort of fencing:
--stonith $TYPE # e.g. "--stonith xvm" to use fence_xvm or "--stonith lha" to use external/ssh
A complete command line might look like:
python ./CTSlab.py --nodes "pcmk-1 pcmk-2 pcmk-3" --outputfile ~/cts.log \
--clobber-cib --populate-resources --test-ip-base 192.168.9.100 \
--stonith xvm 50
For more options, use the --help option.
NOTE: Perhaps more convenient way to compile a command line like above is to use cluster_test script that, at least in the source repository, sits in the same directory as this very file.
To extract the result of a particular test, run:
crm_report -T $test
Pacemaker and CTS have various options for testing memory management. On the cluster nodes, pacemaker components will use various environment variables to control these options. How these variables are set varies by OS, but usually they are set in the /etc/sysconfig/pacemaker or /etc/default/pacemaker file.
Valgrind is a program for detecting memory management problems (such as use-after-free errors). If you have valgrind installed, you can enable it by setting the following environment variables on all cluster nodes:
PCMK_valgrind_enabled=attrd,cib,crmd,lrmd,pengine,stonith-ng
VALGRIND_OPTS="--leak-check=full --trace-children=no --num-callers=25
--log-file=/var/lib/pacemaker/valgrind-%p
--suppressions=/usr/share/pacemaker/tests/valgrind-pcmk.suppressions
--gen-suppressions=all"
and running CTS with these options:
--valgrind-tests --valgrind-procs="attrd cib crmd lrmd pengine stonith-ng"
These options should only be set while specifically testing memory management, because they may slow down the cluster significantly, and they will disable writes to the CIB. If desired, you can enable valgrind on a subset of pacemaker components rather than all of them as listed above.
Valgrind will put a text file for each process in the location specified by valgrind's --log-file option. For explanations of the messages valgrind generates, see http://valgrind.org/docs/manual/mc-manual.html
Separately, if you are using the GNU C library, the G_SLICE, MALLOC_PERTURB_, and MALLOC_CHECK_ environment variables can be set to affect the library's memory management functions.
When using valgrind, G_SLICE should be set to “always-malloc”, which helps valgrind track memory by always using the malloc() and free() routines directly. When not using valgrind, G_SLICE can be left unset, or set to “debug-blocks”, which enables the C library to catch many memory errors but may impact performance.
If the MALLOC_PERTURB_ environment variable is set to an 8-bit integer, the C library will initialize all newly allocated bytes of memory to the integer value, and will set all newly freed bytes of memory to the bitwise inverse of the integer value. This helps catch uses of uninitialized or freed memory blocks that might otherwise go unnoticed. Example:
MALLOC_PERTURB_=221
If the MALLOC_CHECK_ environment variable is set, the C library will check for certain heap corruption errors. The most useful value in testing is 3, which will cause the library to print a message to stderr and abort execution. Example:
MALLOC_CHECK_=3
Valgrind should be enabled for either all nodes or none, but the C library variables may be set differently on different nodes.
If the pacemaker_remoted daemon is installed on all cluster nodes, CTS will enable remote node tests.
The remote node tests choose a random node, stop the cluster on it, start pacemaker_remote on it, and add an ocf:pacemaker:remote resource to turn it into a remote node. When the test is done, CTS will turn the node back into a cluster node.
To avoid conflicts, CTS will rename the node, prefixing the original node name with “remote-”. For example, “pcmk-1” will become “remote-pcmk-1”.
The name change may require special stonith configuration, if the fence agent expects the node name to be the same as its hostname. A common approach is to specify the “remote-” names in pcmk_host_list. If you use pcmk_host_list=all, CTS will expand that to all cluster nodes and their “remote-” names. You may additionally need a pcmk_host_map argument to map the “remote-” names to the hostnames. Example:
--stonith xvm --stonith-args \ pcmk_arg_map=domain:uname,pcmk_host_list=all,pcmk_host_map=remote-pcmk-1:pcmk-1;remote-pcmk-2:pcmk-2
When running the remote node tests, the pacemaker components on the cluster nodes can be run under valgrind as described in the “Memory testing” section. However, pacemaker_remote cannot be run under valgrind that way, because it is started by the OS's regular boot system and not by pacemaker.
Details vary by system, but the goal is to set the VALGRIND_OPTS environment variable and then start pacemaker_remoted by prefixing it with the path to valgrind.
The init script and systemd service file provided with pacemaker_remote will load the pacemaker environment variables from the same location used by other pacemaker components, so VALGRIND_OPTS will be set correctly if using one of those.
For an OS using systemd, you can override the ExecStart parameter to run valgrind. For example:
mkdir /etc/systemd/system/pacemaker_remote.service.d cat >/etc/systemd/system/pacemaker_remote.service.d/valgrind.conf <<EOF [Service] ExecStart= ExecStart=/usr/bin/valgrind /usr/sbin/pacemaker_remoted EOF
If the --container-tests option is given to CTS, it will enable testing of LXC resources (currently only the RemoteLXC test, which starts a remote node using an LXC container).
The container tests have additional package dependencies (see the toplevel README). Also, SELinux must be enabled (in either permissive or enforcing mode), libvirtd must be enabled and running, and root must be able to ssh without a password between all cluster nodes (not just from the test machine). Before running the tests, you can verify your environment with:
/usr/share/pacemaker/tests/cts/lxc_autogen.sh -v
LXC tests will create two containers with hardcoded parameters: a NAT‘ed bridge named virbr0 using the IP network 192.168.123.0/24 will be created on the cluster node hosting the containers; the host will be assigned 52:54:00:A8:12:35 as the MAC address and 192.168.123.1 as the IP address. Each container will be assigned a random MAC address starting with 52:54:, the IP address 192.168.123.11 or 192.168.123.12, the hostname lxc1 or lxc2 (which will be added to the host’s /etc/hosts file), and 196MB RAM.
The test will revert all of the configuration when it is done.
The CTS scripts run “ssh -l root” so you don't have to do any of your testing logged in as root on the test machine. Here is how to allow such connections without requiring a password to be entered each time:
On your test exerciser, create an SSH key if you do not already have one. Most commonly, SSH keys will be in your ~/.ssh directory, with the private key file not having an extension, and the public key file named the same with the extension “.pub” (for example, ~/.ssh/id_rsa.pub).
If you don't already have a key, you can create one with:
ssh-keygen -t rsa
From your test exerciser, authorize your SSH public key for root on all test machines (both the exerciser and the cluster test machines):
ssh-copy-id -i ~/.ssh/id_rsa.pub root@$MACHINE
You will probably have to provide your password, and possibly say “yes” to some questions about accepting the identity of the test machines.
The above assumes you have a RSA SSH key in the specified location; if you have some other type of key (DSA, ECDSA, etc.), use its file name in the -i option above.
To test, try this command from the exerciser machine for each of your cluster machines, and for the exerciser machine itself.
ssh -l root $MACHINE
If this works without prompting for a password, you're in business. If not, look at the documentation for your version of ssh.