Archive for June, 2009

Testing out live CD distributions with KVM

I read over the latest KVM putback log last night, and saw that KVM now supports booting from ISO images that are accessible via HTTP (it uses libcurl under the covers). This is pretty fricking cool, and allow you to boot in recovery mode without requiring local media or PXE, and provides a super easy […]

Accessing the Python help facility from the Python shell

Python has a ton of useful modules, and the built-in help facility is extremely useful for gaining quick access to a description of methods in a given module. Once a module is imported with import: >>> import pexpect You can run dir(MODULE_NAME) to view the list of methods in the module: >>> dir(pexpect) ['EOF', 'ExceptionPexpect', […]

How does crossbow deal with MAC address conflicts?

When I gave my presentation on Solaris network virtualization a few months back, one of the folks in the audience asked me how Crossbow deals with duplicate MAC detection. I didn’t have a solid answer for the gentlemen that asked, but thanks to Nicolas Droux from Solaris kernel engineering, now I do. Here is what […]

Implementing locks in shell scripts

I have been working on a shell script that manages lxc-containers, and came across a use case last where it is possible for two yum processes to interfere with each other. To ensure that only one yum process is run at a single point in time, I implemented file based locks using flock(1). Flock makes […]

Downloading Fedora and CentOS source code with yumdownloader

One of the things I really like about Linux is the availability of source code for the kernel and userland applications. If I encounter an issue where a program is misbehaving for some given reason, I can grab a source RPM from a network repository and start poking around to see what is going on. […]

Installing lxc-containers on Fedora hosts

During the Q&A period of my KVM presentation the other night, the world famous Mike Warfield tipped me off to the lxc-container project. Lxc-containers are a lightweight virtualization solution similar to Solaris zones and openvz, and allow you to create one or more virtual execution environments on a Linux server. It appears all of the […]

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