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Automated VM Creation and Testing
We now have the ability to automatically build and test Mininet VM images.
Automated VM Creation
mininet/util/vm/build.py script can automate creation of
.ovf VM images as follows:
build.py takes a list of build flavors, which may be listed using
build.pywill create a
vmtestdirectory in your home directory and store cached ISOs and base VM images there. This feature is not configurable at this time.
The first time a new flavor is used, its ISO installer image will be downloaded and a base image will be created (i.e. a basic Ubuntu installation including the
If the base image is already there, it will be reused as the base image for the copy-on-write
.qcow2image created during the build process.
VM images and ISOs are large and can fill up your storage very quickly.
.qcow2disk image and converts it into a
.vmdkimage, which can be used by (kvm, VirtualBox, VMware, etc.)
By default, the
.qcow2image is deleted after it is converted into a
.vmdk; if you specify the
--qcow2option, then that image will not be deleted (but the
.vmdkwill still be created.)
By default, VM output (from base image creation as well as Mininet VM installation) is logged to log files; specifying the
--verbose) option overrides this behavior and logs VM output to the console; this can make it easier to monitor the progress of the script if it is being run interactively.
By default, the script uses
kvmwith hardware acceleration; I routinely use this within a VMware VM using the nested virtualization feature of VMware Fusion (which you need to enable in the VM's processor settings.) You can test whether
kvmcan be used by using the command
kvmcannot be used, you can revert to
qemu's TCG emulation by specifying the
--nokvm) option to
build.py. Note that software emulation may be much slower than hardware virtualization, but it should still work (although performance-sensitive tests such as
Automated VM testing
Once a VM image has been created, it can also be booted automatically for additional testing.
build.py script also has the ability to test existing VM images. For example:
build.py --image mininet-raring32server.vmdk --test core
will boot a VM from disk image
mininet-raring32server.vmdk and run the
core test. (
build.py -h will list available tests.)
Additionally, you can specify a branch to check out and test in the VM, for example
build.py --image mininet-vm.vmdk --branch devel/myfeature --test sanity
would boot from the specified image, check out the
devel/myfeature branch from the Mininet github repository, and run the
Currently the script runs a simple sanity test (
--test pingall) as well as the Mininet core tests (
make test); the entire boot and test completes in less than 90 seconds on my laptop.
In the future, we will add the option to specify additional (and lengthier) tests.
As part of the boot, the kernel and initial RAM disk (initrd) are extracted from the image; this is necessary so that we can boot the VM with a serial console for
The base disk image should be unaffected by the test process, since it is only used as backing store for a COW (copy-on-write) image, which is used for all changes to the file system and is deleted after VM shutdown.
The boot and test procedure creates a temporary directory for temporary files (kernel, initrd, COW image) and deletes if upon completion.