I was writing some basic RSpec tests for a puppet module this morning, methodically adding in fixtures and hiera data items to get the module to compile under the spec tests.

Then I hit this error:

Failures:

1) profile_puppet::master supported operating systems profile_puppet::master class without any parameters on redhat 6.4 should compile into a catalogue without dependency cycles
Failure/Error: it { should compile.with_all_deps }
NoMethodError:
undefined method `groups' for nil:NilClass
# ./spec/classes/init_spec.rb:36:in `block (5 levels) in '

Uh oh, that doesn't look good. I did what I always do in such circumstances and googled the error message: puppet NoMethodError: undefined method `groups' for nil:NilClass. The first hit was https://tickets.puppetlabs.com/browse/PUP-1547 which describes my situation completely (I am testing for RHEL 6.4 on OSX).

What's even better is that the ticket was updated 3 days ago with a pull request that fixes the issue. I applied the change locally, it worked perfectly, and I was able to complete my task.

Try doing that with proprietary software.

In his talk at Puppetconf 2013, James Fryman mentioned a blog post by James White which contains a list of guidelines for management which has come to be known as the jameswhite manifesto.

Here’s the same list but unconstrained by a fixed-width text box so you can actually read it. 🙂

Rules

On Infrastructure

  • There is one system, not a collection of systems.
  • The desired state of the system should be a known quantity.
  • The “known quantity” must be machine parseable.
  • The actual state of the system must self-correct to the desired state.
  • The only authoritative source for the actual state of the system is the system.
  • The entire system must be deployable using source media and text files.

On Buying Software

  • Keep the components in the infrastructure simple so it will be better understood.
  • All products must authenticate and authorize from external, configurable sources.
  • Use small tools that interoperate well, not one “do everything poorly” product.
  • Do not implement any product that no one in your organization has administered.
  • “Administered” does not mean saw it in a rigged demo, online or otherwise.
  • If you must deploy the product, hire someone who has implemented it before to do so.

On Automation

  • Do not author any code you would not buy.
  • Do not implement any product that does not provide an API.
  • The provided API must have all functionality that the application provides.
  • The provided API must be tailored to more than one language and platform.
  • Source code counts as an API, and may be restricted to one language or platform.
  • The API must include functional examples and not requre someone to be an expert on the product to use.
  • Do not use any product with configurations that are not machine parseable and machine writeable.
  • All data stored in the product must be machine readable and writeable by applications other than the product itself.
  • Writing hacks around the deficiencies in a product should be less work than writing the product’s functionality.

In general

  • Keep the disparity in your architecture to an absolute minimum.
  • Use Set Theory to accomplish this.
  • Do not improve manual processes if you can automate them instead.
  • Do not buy software that requires bare-metal.
  • Manual data transfers and datastores maintained manually are to be avoided.

I'm a big fan of provisioning tools, particularly puppet.

Sometimes I just want to quickly throw a clean install on a new machine that I can then use to provision other machines (and even to re-configure the puppetmaster).

So, I wrote a script to do just that. The only requirement is a minimal install of your favourite CentOS/Red Hat/Fedora OS and the script will do the rest.

It's available from github: https://github.com/robinbowes/puppet-server-bootstrap

I recently offered to help out with the hosting of a WordPress  site. It’s currently hosted somewhere with no shell access – just ftp – and there are a lot of images to transfer.

I quickly figured out I could use wget to mirror the site, using something like:

wget -m ftp://username:password@example.com

However, this broke in this case because the username for the site contained an @ character (the username was user@example.com).

Turns out the solution was to encode the special chars using HTML notation. This is the command that did the trick:

wget -m ftp://user%40example.com:password@example.com

This is one of those “dead easy so why so hard” issues.

I use chrome on Fedora 18 on my home desktop. I have put up with a non-working java plugin for some time (to be honest, I’ve not been to bothered given java’s history of security issues).

Here’s how to enable the java plugin under chrome on Fedora 18 using icedtea (openjdk).

sudo yum install icedtea-web
sudo mkdir -p /usr/lib64/firefox/plugins
sudo ln -s /usr/lib64/IcedTeaPlugin.so /usr/lib64/firefox/plugins/libjavaplugin.so

Now restart chrome and go here to test the java plugin now works.

I wanted to create a full-disk partition, with optimal alignment, on a 4TB disk under CentOS 6.4 and use it as an LVM PV.

fdisk doesn’t work on disks larger than 2TB so I used parted:

parted -a optimal /dev/sda
(parted) mklabel
Warning: The existing disk label on /dev/sda will be destroyed and all data on this disk will be lost. Do you want to continue?
Yes/No? Yes
(parted) mkpart primary ext2 0% 100%
(parted) set 1 lvm on

Some time ago, I wrote up how I created RPMs for ruby gems to simplify installation on EL-flavoured distributions. In the comments for that article, Jordan Sissel pointed me at his fpm tool which I said I’d check out if I ever needed to build any more rubygem RPMs.

Well, that time has come. I wanted to deploy a later version of capistrano across a client’s infrastructure and my previous approach didn’t work so I grabbed fpm and did this:

mkdir ~/tmp/gems
cd ~/tmp/gems
gem install --no-ri --no-rdoc --install-dir . capistrano
find ./cache -name '*.gem' | xargs -rn1 fpm -s gem -t rpm
ls *.rpm
rubygem-capistrano-2.15.4-1.noarch.rpm	rubygem-net-scp-1.1.0-1.noarch.rpm   rubygem-net-ssh-2.6.7-1.noarch.rpm
rubygem-highline-1.6.19-1.noarch.rpm	rubygem-net-sftp-2.1.2-1.noarch.rpm  rubygem-net-ssh-gateway-1.2.0-1.noarch.rpm

Nice and easy. Kudos whack!

My Note 2 recently started apparently locking up/freezing and apparently required powering off to fix it.

Thanks to this post, I discovered that this seems to be a "known" problem with the eMMC chip which is susceptible to "Sudden Death Syndrome"

There is an app to determine if your phone has the chip that is affected, and another app to write data to every area of the chip to "fix" the issue.

My phone now appears to be back to normal.

We have app servers with smallish local file systems and application data mounted over NFS.

Sometimes I want to find all files matching a particular set of criteria but don't want to traverse the NFS mounts.

Here's how to do it:

find / -group sophosav -print -o -fstype nfs -prune

Ordering is important, as is the explict inclusion of -print. If you omit this, it will print the name(s) of the NFS mounts as well.

Change start location (/) and criteria (-group sophosav) to suit your own purposes.

I was experiencing problems with dnscache not resolving certain domains. On inspection, it turned out to be akamai-hosted domains that were failing. A quick google turned up this thread from 2004 (!), and a little further digging turned up this patch.

I tweaked the patch a little to set QUERY_MAXLOOP to 1000 (original value: 100, value in patch: 160), and rebuilt.

All works just fine now:

 

[robin@dist ~]$ env DNSCACHEIP=192.168.1.90 dnsqr A www.cisco.com
1 www.cisco.com:
212 bytes, 1+5+0+0 records, response, noerror
query: 1 www.cisco.com
answer: www.cisco.com 0 CNAME www.cisco.com.akadns.net
answer: www.cisco.com.akadns.net 0 CNAME wwwds.cisco.com.edgekey.net
answer: wwwds.cisco.com.edgekey.net 0 CNAME wwwds.cisco.com.edgekey.net.globalredir.akadns.net
answer: wwwds.cisco.com.edgekey.net.globalredir.akadns.net 0 CNAME e144.dscb.akamaiedge.net
answer: e144.dscb.akamaiedge.net 12 A 2.19.144.170