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Keir Fraser
aac518b954
In various places in documentation and code, IP addresses are provided as examples, defaults, or dummy configuration. In general the specific IP addresses used in Xen are not always appropriate. (For example, 1.2.3.4 is used in a few places!) The following addresses should be used: * For examples and documentation, 192.0.2.0/24. (See RFC3330.) * For defaults for private networks, a random network from RFC1918. I have randomly selected 172.30.206.0/24 for this purpose and documented this in at the only registry I know of, www.ucam.org/cam-grin. This network should henceforth be used for default configurations of local bridges, test networks, etc. in Xen tools. The following addresses should NOT be used: * 10.0.*.*, 10.1.*.*, 192.168.0.*, 192.168.1.*, etc. Using these addresses gives greatly increased likelihood of collision, as ignorant network administrators and reckless middlebox vendors often pick networks from the bottom of 10/8 and 192.168/16. * 169.254.*.*. These are reserved for zeroconf (ad-hoc networking) and should not be used for Xen private networks, bridges, etc., etc. Use of these addresses by Xen scripts causes trouble on hosts (eg laptops) which find themselves in ad-hoc networking environments. I think this is not hypothetical (!) since at least one Linux distribution have specific code to detect this case and cause Xen startup to fail iff the host already has an external zeroconf address. * 1.2.3.4. WTF !? I have also used 127.0.255.255 in one place where apparently a dummy address is needed (some Linux kernels won't accept a lack of an NFS server address). If 127.0.255.255 is mistakenly used it is unlikely to do any damage to real traffic even if it does escape into the network at large. Signed-off-by: Ian Jackson <ian.jackson@eu.citrix.com>
137 lines
4.8 KiB
Plaintext
137 lines
4.8 KiB
Plaintext
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Writing Tests HOWTO
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===================
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One goal for xm-test is to make test writing very easy. Xm-test includes
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a library in lib/XmTestLib that contains all the necessary methods for
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creating and shutting down domains. Include the library in your test by
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importing it:
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from XmTestLib import *
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Guidelines
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==========
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1. Tests should be short and single purposed. This means testing as
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little as possible in a single test. Do not overload tests. The more
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that's in a test the more difficult it is to track down what failed.
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2. Tests should report as much information as possible when calling
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FAIL() or SKIP().
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3. A test should report SKIP() only if it cannot be run on the current
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machine or it makes no sense to run it. SMP tests on an UP system,
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for example, may not make sense. Or, there are some tests for
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para-virtualized guests that won't work on a fully virtualized
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guest.
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4. Use the traceCommand() function to run commands on Domain0, the
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Xen management domain. This function logs everything, which is useful
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in case of failure.
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5. Use the domain's console.runCmd method to run commands on a guest
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domain. This ensures logging and consistency. Please see 'Creating
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and Using Domains' below for an example.
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6. Tests need to capture and handle libary exceptions such as:
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- ConsoleError can be raised when sending a command to a console.
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- DomainError can be raised when a domain is started, indicating
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a possible configuration error.
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- TimeoutError can be raised when the traceCommand() method is used.
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7. Tests shouldn't depend on where the test is being run from or the
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system on which it is run.
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8. Please use the existing tests for a guide, especially:
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- create/01_create_basic_pos.py
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- create/13_create_multinic_pos.py
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- memset/01_memset_basic_pos.py
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- reboot/01_reboot_basic_pos.py
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- migrate/01_migrate_localhost_pos.py
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Creating and Using Domains
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==========================
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Xen domains, both full and para virtualized, are represented by the
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XmTestDomain class. The class contains methods for starting a Xen domain,
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shutting it down, or destroying it. Consoles, used to execute commands
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on guest test domains, are opened and closed through the XmTestDomain
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class. Devices, which are represented by the XenDevice class, are also
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added and removed using XmTestDomain methods.
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Here's a simple example for creating a domain, opening a console, running
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a command, and then shutting down the domain:
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1) Create a domain:
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domain = XmTestDomain()
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2) Start the domain and grab a console:
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try:
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console = domain.start()
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except DomainError, e:
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if verbose:
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print "Failed to create test domain because:"
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print e.extra
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FAIL(str(e))
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3) Run a command inside the new domain using the console, saving the
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console log if an error is encountered:
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try:
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# Run 'ls'
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run = console.runCmd("ls")
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except ConsoleError, e:
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saveLog(console.getHistory())
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FAIL(str(e))
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4) Stop the domain, which nicely shuts it down:
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domain.stop()
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Writing Tests with Networking
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=============================
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The xm-test suite includes the ability to test networking for domains.
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Networking is configured at configuration time. While testing NAT and
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routing environments in the future, the current xm-test only supports
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a bridging environment. Xm-test currently only supports a range of
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IPs, the dhcp feature will be added soon.
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The network tests will need to know what IPs to use. IPs are
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configured when you build xm-test. Xm-test by default a range chosen
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at random from the RFC1918 private use space, and published at
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www.ucam.org/cam-grin, 172.30.206.1-172.30.206.254 from
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172.30.206.0/24. If you'd like to set a new range, do so at configure
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time, a netmask and network address must also be defined:
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# ./configure --with-net-ip-range=192.0.2.1-192.0.2.100 --with-network-address=192.0.2.0 --with-netmask=255.255.255.0
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The tests will not need to set network information, this is done by
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the library once it's configured.
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As mentioned above, xm-test's goal is to make writing tests easy. Creating
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domains with networking should also be easy. To create a domain with
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a single network interface, tests can use a XmTestNetDomain object. It
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creates a XenNetDevice for the domain automatically using the pre-configured
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IP information. Otherwise, a network interface can be added to a domain
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prior to starting it (the ability to attach devices will be added):
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domain = XmTestDomain()
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domain.newDevice(XenNetDevice, "eth0")
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domain.newDevice(XenNetDevice, "eth1")
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Here, the domain is created and then the XenDomain factory newDevice
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is called to create a new device of class XenNetDevice to the domain.
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The xm-test library will automatically assign an IP from the configured
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list, execute ifconfig on the guest domain console, and create an
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alias on Domain0.
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