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The Rise of the DevOps movement

This is a repost of an article I wrote for the Acquia Blog some time ago.

DevOps, DevOps, DevOps … the whole world is talking about DevOps, but what is DevOps?

Since Munich 2012, DrupalCon had a dedicated devops track. After talking to
a lot of people in Prague last month, I realized that the concept of DevOps is still very unclear to a lot of developers. To a large part of the development community, DevOps development still means folks working on 'the infrastructure part' of the development life cycle and for some it just means simply deploying Drupal, being concerned about purely keeping the site alive etc.

Obviously that's not what DevOps is about, so let's take a step back and find out how it all started.

Like all good things, Drupal included, DevOps is a Belgian thing!

Back in 2009 DevopsDays Europe was created because a group of people met over and over again at different conferences throughout the world and didn’t have a common devops conference to go to. These individuals would talk about software delivery, deployment, build, scale, clustering, management, failure, monitoring and all the important things one needs to think about when running a modern web operation. These folks included Patrick Debois, Julian Simpson, Gildas Le Nadan, Jezz Humble, Chris Read, Matt Rechenburg , John Willis, Lindsay Holmswood and me - Kris Buytaert.

O’Reilly created a conference called, “Velocity,” and that sounded interesting to a bunch of us Europeans, but on our side of the ocean we had to resort to the existing Open Source, Unix, and Agile conferences. We didn't really have a common meeting ground yet. At CloudCamp Antwerp, in the Antwerp Zoo, I started talking to Patrick Debois about ways to fill this gap.

Many different events and activities like John Allspaw and Paul Hammond’s talk at “Velocity”, multiple twitter discussions influenced Patrick to create a DevOps specific event in Gent, which became the very first ‘DevopsDays'. DevopsDays Gent was not your traditional conference, it was a mix between a couple of formal presentations in the morning and open spaces in the afternoon. And those open spaces were where people got most value. The opportunity to talk to people with the same complex problems, with actual experiences in solving them, with stories both about success and failure etc. How do you deal with that oldskool system admin that doesn’t understand what configuration management can bring him? How do you do Kanban for operations while the developers are working in 2 week sprints? What tools do you use to monitor a highly volatile and expanding infrastructure?

From that very first DevopsDays in Gent several people spread out to organize other events John Willis and Damon Edwards started organizing DevopsDays Mountain View, and the European Edition started touring Europe. It wasn’t until this year that different local communities started organizing their own local DevopsDays, e.g in Atlanta, Portland, Austin, Berlin, Paris, Amsterdam, London, Barcelona and many more.

From this group of events a community has grown of people that care about bridging the gap between development and operations, a community of people that cares about delivering holistic business value to their organization.

As a community, we have realized that there needs to be more communication between the different stakeholders in an IT project lifecycle - business owners, developers, operations, network engineers, security engineers – everybody needs to be involved as soon as possible in the project in order to help each other and talk about solving potential pitfalls ages before the application goes live. And when it goes live the communication needs to stay alive too.. We need to talk about maintaining the application, scaling it, keeping it secure . Just think about how many Drupal sites are out there vulnerable to attackers because the required security updates have never been implemented. Why does this happen? It could be because many developers don't try to touch the site anymore..because they are afraid of breaking it.

And this is where automation will help.. if we can do automatic deployments and upgrades of a site because it is automatically tested when developers push their code, upgrading won't be that difficult of a task. Typically when people only update once in 6 months, its a painful and difficult process but when its automated and done regularly, it makes life so much easier.

This ultimately comes down to the idea that the involvement of developers doesn’t end at their last commit. Collaboration is key which allows every developer to play a key role in keeping the site up and running, for more happy users. After all software with no users has no value. The involvement of the developers in the ongoing operations of their software shouldn't end before the last end user stops using their applications.

In order to keep users happy we need to get feedback and metrics, starting from the very first phases of development all the way up to production. It means we need to monitor both our application and infrastructure and get metrics from all possible aspects, with that feedback we can learn about potential problems but also about successes.

Finally, summarizing this in an acronym coined by John Willis and Damon Edwards
- CAMS. CAMS says Devops is about Culture, Automation, Measurement and Sharing.
Getting the discussion going on how to do all of that, more specifically in a Drupal environment, is the sharing part .

Hiera data in modules and OS independent puppet

Earlier this year, R.I.Pienaar released his brilliant data in modules hack, a few months ago, I got the chance to start implementing it in Puppet-Gluster, and today I have found the time to blog about it.

What is it?

R.I.’s hack lets you store hiera data inside a puppet module. This can have many uses including letting you throw out the nested mess that is commonly params.pp, and replace it with something file based that is elegant and hierarchical. For my use case, I’m using it to build OS independent puppet modules, without storing this data as code. The secondary win is that porting your module to a new GNU/Linux distribution or version could be as simple as adding a YAML file.

How does it work?

(For the specifics on the hack in general, please read R.I. Pienaar’s blog post. After you’re comfortable with that, please continue…)

In the hiera.yaml data/ hierarchy, I define an OS / version structure that should probably cover all use cases. It looks like this:

---
:hierarchy:
- tree/%{::osfamily}/%{::operatingsystem}/%{::operatingsystemrelease}
- tree/%{::osfamily}/%{::operatingsystem}
- tree/%{::osfamily}
- common

At the bottom, you can specify common data, which can be overridden by OS family specific data (think RedHat “like” vs. Debian “like”), which can be overridden with operating system specific data (think CentOS vs. Fedora), which can finally be overridden with operating system version specific data (think RHEL6 vs. RHEL7).

Grouping the commonalities near the bottom of the tree, avoids duplication, and makes it possible to support new OS versions with fewer changes. It would be especially cool if someone could write a script to refactor commonalities downwards, and to refactor new uniqueness upwards.

This is an except of the Fedora specific YAML file:

gluster::params::package_glusterfs_server: 'glusterfs-server'
gluster::params::program_mkfs_xfs: '/usr/sbin/mkfs.xfs'
gluster::params::program_mkfs_ext4: '/usr/sbin/mkfs.ext4'
gluster::params::program_findmnt: '/usr/bin/findmnt'
gluster::params::service_glusterd: 'glusterd'
gluster::params::misc_gluster_reload: '/usr/bin/systemctl reload glusterd'

Since we use full paths in Puppet-Gluster, and since they are uniquely different in Fedora (no more: /bin) it’s nice to specify them all here. The added advantage is that you can easily drop in different versions of these utilities if you want to test a patched release without having to edit your system utilities. In addition, you’ll see that the OS specific RPM package name and service names are in here too. On a Debian system, they are usually different.

Dependencies:

This depends on Puppet >= 3.x and having the puppet-module-data module included. I do so for integration with vagrant like so.

Should I still use params.pp?

I think that this answer is yes. I use a params.pp file with a single class specifying all the defaults:

class gluster::params(
    # packages...
    $package_glusterfs_server = 'glusterfs-server',

    $program_mkfs_xfs = '/sbin/mkfs.xfs',
    $program_mkfs_ext4 = '/sbin/mkfs.ext4',

    # services...
    $service_glusterd = 'glusterd',

    # misc...
    $misc_gluster_reload = '/sbin/service glusterd reload',

    # comment...
    $comment = ''
) {
    if "${comment}" == '' {
        warning('Unable to load yaml data/ directory!')
    }

    # ...

}

In my data/common.yaml I include a bogus comment canary so that I can trigger a warning if the data in modules module isn’t working. This shouldn’t be a fail as long as you want to allow backwards compatibility, otherwise it should be! The defaults I use correspond to the primary OS I hack and use this module with, which in this case is CentOS 6.x.

To use this data in your module, include the params.pp file, and start using it. Example:

include gluster::params
package { "${::gluster::params::package_glusterfs_server}":
    ensure => present,
}

Unfortunately the readability isn’t nearly as nice as it is without this, however it’s an essential evil, due to the puppet language limitations.

Common patterns:

There are a few common code patterns, which you might need for this technique. The first few, I’ve already mentioned above. These are the tree layout in hiera.yaml, the comment canary, and the params.pp defaults. There’s one more that you might find helpful…

The split package pattern:

Certain packages are split into multiple pieces on some operating systems, and grouped together on others. This means there isn’t always a one-to-one mapping between the data and the package type. For simple cases you can use a hiera array:

# this hiera value could be an array of strings...
package { $::some_module::params::package::some_package_list:
    ensure => present,
    alias => 'some_package',
}
service { 'foo':
    require => Package['some_package'],
}

For this to work you must always define at least one element in the array. For more complex cases you might need to test for the secondary package in the split:

if "${::some_module::params::package::some_package}" != '' {
    package { "${::some_module::params::package::some_package}":
        ensure => present,
        alias => 'some_package', # or use the $name and skip this
    }
}

service { 'foo':
    require => "${::some_module::params::package::some_package}" ? {
        '' => undef,
        default => Package['some_package'],
    },
}

This pattern is used in Puppet-Gluster in more than one place. It turns out that it’s also useful when optional python packages get pulled into the system python. (example)

Hopefully you found this useful. Please help increase the multi-os aspect of Puppet-Gluster by submitting patches to the YAML files, and by testing it on your favourite GNU/Linux distro!

Happy hacking!

James

 


Hiera data in modules and OS independent puppet

Earlier this year, R.I.Pienaar released his brilliant data in modules hack, a few months ago, I got the chance to start implementing it in Puppet-Gluster, and today I have found the time to blog about it.

What is it?

R.I.’s hack lets you store hiera data inside a puppet module. This can have many uses including letting you throw out the nested mess that is commonly params.pp, and replace it with something file based that is elegant and hierarchical. For my use case, I’m using it to build OS independent puppet modules, without storing this data as code. The secondary win is that porting your module to a new GNU/Linux distribution or version could be as simple as adding a YAML file.

How does it work?

(For the specifics on the hack in general, please read R.I. Pienaar’s blog post. After you’re comfortable with that, please continue…)

In the hiera.yaml data/ hierarchy, I define an OS / version structure that should probably cover all use cases. It looks like this:

---
:hierarchy:
- tree/%{::osfamily}/%{::operatingsystem}/%{::operatingsystemrelease}
- tree/%{::osfamily}/%{::operatingsystem}
- tree/%{::osfamily}
- common

At the bottom, you can specify common data, which can be overridden by OS family specific data (think RedHat “like” vs. Debian “like”), which can be overridden with operating system specific data (think CentOS vs. Fedora), which can finally be overridden with operating system version specific data (think RHEL6 vs. RHEL7).

Grouping the commonalities near the bottom of the tree, avoids duplication, and makes it possible to support new OS versions with fewer changes. It would be especially cool if someone could write a script to refactor commonalities downwards, and to refactor new uniqueness upwards.

This is an except of the Fedora specific YAML file:

gluster::params::package_glusterfs_server: 'glusterfs-server'
gluster::params::program_mkfs_xfs: '/usr/sbin/mkfs.xfs'
gluster::params::program_mkfs_ext4: '/usr/sbin/mkfs.ext4'
gluster::params::program_findmnt: '/usr/bin/findmnt'
gluster::params::service_glusterd: 'glusterd'
gluster::params::misc_gluster_reload: '/usr/bin/systemctl reload glusterd'

Since we use full paths in Puppet-Gluster, and since they are uniquely different in Fedora (no more: /bin) it’s nice to specify them all here. The added advantage is that you can easily drop in different versions of these utilities if you want to test a patched release without having to edit your system utilities. In addition, you’ll see that the OS specific RPM package name and service names are in here too. On a Debian system, they are usually different.

Dependencies:

This depends on Puppet >= 3.x and having the puppet-module-data module included. I do so for integration with vagrant like so.

Should I still use params.pp?

I think that this answer is yes. I use a params.pp file with a single class specifying all the defaults:

class gluster::params(
    # packages...
    $package_glusterfs_server = 'glusterfs-server',

    $program_mkfs_xfs = '/sbin/mkfs.xfs',
    $program_mkfs_ext4 = '/sbin/mkfs.ext4',

    # services...
    $service_glusterd = 'glusterd',

    # misc...
    $misc_gluster_reload = '/sbin/service glusterd reload',

    # comment...
    $comment = ''
) {
    if "${comment}" == '' {
        warning('Unable to load yaml data/ directory!')
    }

    # ...

}

In my data/common.yaml I include a bogus comment canary so that I can trigger a warning if the data in modules module isn’t working. This shouldn’t be a fail as long as you want to allow backwards compatibility, otherwise it should be! The defaults I use correspond to the primary OS I hack and use this module with, which in this case is CentOS 6.x.

To use this data in your module, include the params.pp file, and start using it. Example:

include gluster::params
package { "${::gluster::params::package_glusterfs_server}":
    ensure => present,
}

Unfortunately the readability isn’t nearly as nice as it is without this, however it’s an essential evil, due to the puppet language limitations.

Common patterns:

There are a few common code patterns, which you might need for this technique. The first few, I’ve already mentioned above. These are the tree layout in hiera.yaml, the comment canary, and the params.pp defaults. There’s one more that you might find helpful…

The split package pattern:

Certain packages are split into multiple pieces on some operating systems, and grouped together on others. This means there isn’t always a one-to-one mapping between the data and the package type. For simple cases you can use a hiera array:

# this hiera value could be an array of strings...
package { $::some_module::params::package::some_package_list:
    ensure => present,
    alias => 'some_package',
}
service { 'foo':
    require => Package['some_package'],
}

For this to work you must always define at least one element in the array. For more complex cases you might need to test for the secondary package in the split:

if "${::some_module::params::package::some_package}" != '' {
    package { "${::some_module::params::package::some_package}":
        ensure => present,
        alias => 'some_package', # or use the $name and skip this
    }
}

service { 'foo':
    require => "${::some_module::params::package::some_package}" ? {
        '' => undef,
        default => Package['some_package'],
    },
}

This pattern is used in Puppet-Gluster in more than one place. It turns out that it’s also useful when optional python packages get pulled into the system python. (example)

Hopefully you found this useful. Please help increase the multi-os aspect of Puppet-Gluster by submitting patches to the YAML files, and by testing it on your favourite GNU/Linux distro!

Happy hacking!

James

 


Monitorama PDX & my metrics 2.0 presentation

Earlier this month we had another iteration of the Monitorama conference, this time in Portland, Oregon.


(photo by obfuscurity)


read more

Restarting GNOME shell via SSH

When GNOME shell breaks, you get to keep both pieces. The nice thing about shell failures in GNOME 3, is that if you’re able to do a restart, the active windows are mostly not disturbed. The common way to do this is to type ALT-F2, r, <ENTER>.

Unfortunately, you can’t always type that in if your shell is very borked. If you are lucky enough to have SSH access, and another machine, you can log in remotely and run this script:

#!/bin/bash
export DISPLAY=:0.0
{ `gnome-shell --replace &> /dev/null`; } < /dev/stdin &

This will restart the shell, but also allow you to disconnect from the terminal without killing the shell. If you’re not sure what I mean, try running gnome-shell --replace by itself, and then disconnect.

The script is available as a gist. Download it, put it inside your ~/bin/ and chmod u+x it. Hopefully you don’t need to use it!

Happy hacking,

James

 


Restarting GNOME shell via SSH

When GNOME shell breaks, you get to keep both pieces. The nice thing about shell failures in GNOME 3, is that if you’re able to do a restart, the active windows are mostly not disturbed. The common way to do this is to type ALT-F2, r, <ENTER>.

Unfortunately, you can’t always type that in if your shell is very borked. If you are lucky enough to have SSH access, and another machine, you can log in remotely and run this script:

#!/bin/bash
export DISPLAY=:0.0
{ `gnome-shell --replace &> /dev/null`; } < /dev/stdin &

This will restart the shell, but also allow you to disconnect from the terminal without killing the shell. If you’re not sure what I mean, try running gnome-shell --replace by itself, and then disconnect.

The script is available as a gist. Download it, put it inside your ~/bin/ and chmod u+x it. Hopefully you don’t need to use it!

Happy hacking,

James

 


On Graphite, Whisper and InfluxDB

Graphite, and the storage Achilles heel

Graphite is a neat timeseries metrics storage system that comes with a powerful querying api, mainly due to the whole bunch of available processing functions.
For medium to large setups, the storage aspect quickly becomes a pain point. Whisper, the default graphite storage format, is a simple storage format, using one file per metric (timeseries).
read more

Vagrant on Fedora with libvirt (reprise)

Vagrant has become the de facto tool for devops. Faster iterations, clean environments, and less overhead. This isn’t an article about why you should use Vagrant. This is an article about how to get up and running with Vagrant on Fedora with libvirt easily!

Background:

This article is an update of my original Vagrant on Fedora with libvirt article. There is still lots of good information in that article, but this one should be easier to follow and uses updated versions of Vagrant and vagrant-libvirt.

Why vagrant-libvirt?

Vagrant ships by default with support for virtualbox. This makes sense as a default since it is available on Windows, Mac, and GNU/Linux. Real hackers use GNU/Linux, and in my opinion the best tool for GNU/Linux is vagrant-libvirt. Proprietary, closed source platforms aren’t hackable and therefore aren’t cool!

Another advantage to using the vagrant-libvirt plugin is that it plays nicely with the existing ecosystem of libvirt tools. You can use virsh, virt-manager, and guestfish alongside Vagrant, and if your development work needs to go into production, you can be confident in knowing that it was already tested on the same awesome KVM virtualization platform that your servers run.

Prerequisites:

Let’s get going. What do you need?

  • A Fedora 20 machine

I recommend hardware that supports VT extensions. Most does these days. This should also work with other GNU/Linux distro’s, but I haven’t tested them.

Installation:

I’m going to go through this in a logical hacking order. This means you could group all the yum install commands into a single execution at the beginning, but you would learn much less by doing so.

First install some of your favourite hacking dependencies. I did this on a minimal, headless F20 installation. You might want to add some of these too:

# yum install -y wget tree vim screen mtr nmap telnet tar git

Update the system to make sure it’s fresh:

# yum update -y

Download Vagrant version 1.5.4. No, don’t use the latest version, it probably won’t work! Vagrant has new releases practically as often as there are sunsets, and they typically cause lots of breakages.

$ wget https://dl.bintray.com/mitchellh/vagrant/vagrant_1.5.4_x86_64.rpm

and install it:

# yum install -y vagrant_1.5.4_x86_64.rpm

RVM installation:

In order to get vagrant-libvirt working, you’ll need some ruby dependencies. It turns out that RVM seems to be the best way to get exactly what you need. Use the sketchy RVM installer:

# \curl -sSL https://get.rvm.io | bash -s stable

If you don’t know why that’s sketchy, then you probably shouldn’t be hacking! I did that as root, but it probably works when you run it as a normal user. At this point rvm should be installed. The last important thing you’ll need to do is to add yourself to the rvm group. This is only needed if you installed rvm as root:

# usermod -aG rvm <username>

You’ll probably need to logout and log back in for this to take effect. Run:

$ groups

to make sure you can see rvm in the list. If you ran rvm as root, you’ll want to source the rvm.sh file:

$ source /etc/profile.d/rvm.sh

or simply use a new terminal. If you ran it as a normal user, I think RVM adds something to your ~/.bashrc. You might want to reload it:

$ source ~/.bashrc

At this point RVM should be working. Let’s see which ruby’s it can install:

$ rvm list known

Ruby version ruby-2.0.0-p353 seems closest to what is available on my Fedora 20 machine, so I’ll use that:

$ rvm install ruby-2.0.0-p353

If the exact patch number isn’t available, choose what’s closest. Installing ruby requires a bunch of dependencies. The rvm install command will ask yum for a bunch of dependencies, but if you’d rather install them yourself, you can run:

# yum install -y patch libyaml-devel libffi-devel glibc-headers autoconf gcc-c++ glibc-devel patch readline-devel zlib-devel openssl-devel bzip2 automake libtool bison

GEM installation:

Now we need the GEM dependencies for the vagrant-libvirt plugin. These GEM’s happen to have their own build dependencies, but thankfully I’ve already figured those out for you:

# yum install -y libvirt-devel libxslt-devel libxml2-devel

Now, install the nokogiri gem that vagrant-libvirt needs:

$ gem install nokogiri -v '1.5.11'

and finally we can install the actual vagrant-libvirt plugin:

$ vagrant plugin install --plugin-version 0.0.16 vagrant-libvirt

You don’t have to specify the –plugin-version 0.0.16 part, but doing so will make sure that you get a version that I have tested to be compatible with Vagrant 1.5.4 should a newer vagrant-libvirt release not be compatible with the Vagrant version you’re using. If you’re feeling brave, please test newer versions, report bugs, and write patches!

Making Vagrant more useful:

Vagrant should basically work at this point, but it’s missing some awesome. I’m proud to say that I wrote this awesome. I recommend my bash function and alias additions. If you’d like to include them, you can run:

$ wget https://gist.githubusercontent.com/purpleidea/8071962/raw/ee27c56e66aafdcb9fd9760f123e7eda51a6a51e/.bashrc_vagrant.sh
$ echo '. ~/.bashrc_vagrant.sh' >> ~/.bashrc
$ . ~/.bashrc    # reload

to pull in my most used Vagrant aliases and functions. I’ve written about them before. If you’re interested, please read:

KVM/QEMU installation:

As I mentioned earlier, I’m assuming you have a minimal Fedora 20 installation, so you might not have all the libvirt pieces installed! Here’s how to install any potentially missing pieces:

# yum install -y libvirt{,-daemon-kvm}

This should pull in a whole bunch of dependencies too. You will need to start and (optionally) enable the libvirtd service:

# systemctl start libvirtd.service
# systemctl enable libvirtd.service

You’ll notice that I’m using the systemd commands instead of the deprecated service command. My biggest (only?) gripe with systemd is that the command line tools aren’t as friendly as they could be! The systemctl equivalent requires more typing, and make it harder to start or stop the same service in quick succession, because it buries the action in the middle of the command instead of leaving it at the end!

The libvirtd service should finally be running. On my machine, it comes with a default network which got in the way of my vagrant-libvirt networking. If you want to get rid of it, you can run:

# virsh net-destroy default
# virsh net-undefine default

and it shouldn’t bother you anymore. One last hiccup. If it’s your first time installing KVM, you might run into bz#950436. To workaround this issue, I had to run:

# rmmod kvm_intel
# rmmod kvm
# modprobe kvm
# modprobe kvm_intel

Without this “module re-loading” you might see this error:

Call to virDomainCreateWithFlags failed: internal error: Process exited while reading console log output: char device redirected to /dev/pts/2 (label charserial0)
Could not access KVM kernel module: Permission denied
failed to initialize KVM: Permission denied

Additional installations:

To make your machine somewhat more palatable, you might want to consider installing bash-completion:

# yum install -y bash-completion

You’ll also probably want to add the PolicyKit (polkit) .pkla file that I recommend in my earlier article. Typically that means adding something like:

[Allow james libvirt management permissions]
Identity=unix-user:james
Action=org.libvirt.unix.manage
ResultAny=yes
ResultInactive=yes
ResultActive=yes

as root to somewhere like:

/etc/polkit-1/localauthority/50-local.d/vagrant.pkla

Your machine should now be setup perfectly! The last thing you’ll need to do is to make sure that you get a Vagrantfile that does things properly! Here are some recommendations.

Shared folders:

Shared folders are a mechanism that Vagrant uses to pass data into (and sometimes out of) the virtual machines that it is managing. Typically you can use NFS, rsync, and some provider specific folder sharing like 9p. Using rsync is the simplest to set up, and works exceptionally well. Make sure you include the following line in your Vagrantfile:

config.vm.synced_folder './', '/vagrant', type: 'rsync'

If you want to see an example of this in action, you can have a look at my puppet-gluster Vagrantfile. If you are using the puppet apply provisioner, you will have to set it to use rsync as well:

puppet.synced_folder_type = 'rsync'

KVM performance:

Due to a regression in vagrant-libvirt, the default driver used for virtual machines is qemu. If you want to use the accelerated KVM domain type, you’ll have to set it:

libvirt.driver = 'kvm'

This typically gives me a 5x performance increase over plain qemu. This fix is available in the latest vagrant-libvirt version. The default has been set to KVM in the latest git master.

Dear internets!

I think this was fairly straightforward. You could probably even put all of these commands in a shell script and just run it to get it all going. What we really need is proper RPM packaging. If you can help out, that would be excellent!

If we had a version of vagrant-libvirt alongside a matching Vagrant version in Fedora, then developers and hackers could target that, and we could easily exchange dev environments, hackers could distribute product demos as full vagrant-libvirt clusters, and I could stop having to write these types of articles ;)

I hope this was helpful to you. Please let me know in the comments.

Happy hacking,

James

 


Vagrant on Fedora with libvirt (reprise)

Vagrant has become the de facto tool for devops. Faster iterations, clean environments, and less overhead. This isn’t an article about why you should use Vagrant. This is an article about how to get up and running with Vagrant on Fedora with libvirt easily!

Background:

This article is an update of my original Vagrant on Fedora with libvirt article. There is still lots of good information in that article, but this one should be easier to follow and uses updated versions of Vagrant and vagrant-libvirt.

Why vagrant-libvirt?

Vagrant ships by default with support for virtualbox. This makes sense as a default since it is available on Windows, Mac, and GNU/Linux. Real hackers use GNU/Linux, and in my opinion the best tool for GNU/Linux is vagrant-libvirt. Proprietary, closed source platforms aren’t hackable and therefore aren’t cool!

Another advantage to using the vagrant-libvirt plugin is that it plays nicely with the existing ecosystem of libvirt tools. You can use virsh, virt-manager, and guestfish alongside Vagrant, and if your development work needs to go into production, you can be confident in knowing that it was already tested on the same awesome KVM virtualization platform that your servers run.

Prerequisites:

Let’s get going. What do you need?

  • A Fedora 20 machine

I recommend hardware that supports VT extensions. Most does these days. This should also work with other GNU/Linux distro’s, but I haven’t tested them.

Installation:

I’m going to go through this in a logical hacking order. This means you could group all the yum install commands into a single execution at the beginning, but you would learn much less by doing so.

First install some of your favourite hacking dependencies. I did this on a minimal, headless F20 installation. You might want to add some of these too:

# yum install -y wget tree vim screen mtr nmap telnet tar git

Update the system to make sure it’s fresh:

# yum update -y

Download Vagrant version 1.5.4. No, don’t use the latest version, it probably won’t work! Vagrant has new releases practically as often as there are sunsets, and they typically cause lots of breakages.

$ wget https://dl.bintray.com/mitchellh/vagrant/vagrant_1.5.4_x86_64.rpm

and install it:

# yum install -y vagrant_1.5.4_x86_64.rpm

RVM installation:

In order to get vagrant-libvirt working, you’ll need some ruby dependencies. It turns out that RVM seems to be the best way to get exactly what you need. Use the sketchy RVM installer:

# \curl -sSL https://get.rvm.io | bash -s stable

If you don’t know why that’s sketchy, then you probably shouldn’t be hacking! I did that as root, but it probably works when you run it as a normal user. At this point rvm should be installed. The last important thing you’ll need to do is to add yourself to the rvm group. This is only needed if you installed rvm as root:

# usermod -aG rvm <username>

You’ll probably need to logout and log back in for this to take effect. Run:

$ groups

to make sure you can see rvm in the list. If you ran rvm as root, you’ll want to source the rvm.sh file:

$ source /etc/profile.d/rvm.sh

or simply use a new terminal. If you ran it as a normal user, I think RVM adds something to your ~/.bashrc. You might want to reload it:

$ source ~/.bashrc

At this point RVM should be working. Let’s see which ruby’s it can install:

$ rvm list known

Ruby version ruby-2.0.0-p353 seems closest to what is available on my Fedora 20 machine, so I’ll use that:

$ rvm install ruby-2.0.0-p353

If the exact patch number isn’t available, choose what’s closest. Installing ruby requires a bunch of dependencies. The rvm install command will ask yum for a bunch of dependencies, but if you’d rather install them yourself, you can run:

# yum install -y patch libyaml-devel libffi-devel glibc-headers autoconf gcc-c++ glibc-devel patch readline-devel zlib-devel openssl-devel bzip2 automake libtool bison

GEM installation:

Now we need the GEM dependencies for the vagrant-libvirt plugin. These GEM’s happen to have their own build dependencies, but thankfully I’ve already figured those out for you:

# yum install -y libvirt-devel libxslt-devel libxml2-devel

Now, install the nokogiri gem that vagrant-libvirt needs:

$ gem install nokogiri -v '1.5.11'

and finally we can install the actual vagrant-libvirt plugin:

$ vagrant plugin install --plugin-version 0.0.16 vagrant-libvirt

You don’t have to specify the –plugin-version 0.0.16 part, but doing so will make sure that you get a version that I have tested to be compatible with Vagrant 1.5.4 should a newer vagrant-libvirt release not be compatible with the Vagrant version you’re using. If you’re feeling brave, please test newer versions, report bugs, and write patches!

Making Vagrant more useful:

Vagrant should basically work at this point, but it’s missing some awesome. I’m proud to say that I wrote this awesome. I recommend my bash function and alias additions. If you’d like to include them, you can run:

$ wget https://gist.githubusercontent.com/purpleidea/8071962/raw/ee27c56e66aafdcb9fd9760f123e7eda51a6a51e/.bashrc_vagrant.sh
$ echo '. ~/.bashrc_vagrant.sh' >> ~/.bashrc
$ . ~/.bashrc    # reload

to pull in my most used Vagrant aliases and functions. I’ve written about them before. If you’re interested, please read:

KVM/QEMU installation:

As I mentioned earlier, I’m assuming you have a minimal Fedora 20 installation, so you might not have all the libvirt pieces installed! Here’s how to install any potentially missing pieces:

# yum install -y libvirt{,-daemon-kvm}

This should pull in a whole bunch of dependencies too. You will need to start and (optionally) enable the libvirtd service:

# systemctl start libvirtd.service
# systemctl enable libvirtd.service

You’ll notice that I’m using the systemd commands instead of the deprecated service command. My biggest (only?) gripe with systemd is that the command line tools aren’t as friendly as they could be! The systemctl equivalent requires more typing, and make it harder to start or stop the same service in quick succession, because it buries the action in the middle of the command instead of leaving it at the end!

The libvirtd service should finally be running. On my machine, it comes with a default network which got in the way of my vagrant-libvirt networking. If you want to get rid of it, you can run:

# virsh net-destroy default
# virsh net-undefine default

and it shouldn’t bother you anymore. One last hiccup. If it’s your first time installing KVM, you might run into bz#950436. To workaround this issue, I had to run:

# rmmod kvm_intel
# rmmod kvm
# modprobe kvm
# modprobe kvm_intel

Without this “module re-loading” you might see this error:

Call to virDomainCreateWithFlags failed: internal error: Process exited while reading console log output: char device redirected to /dev/pts/2 (label charserial0)
Could not access KVM kernel module: Permission denied
failed to initialize KVM: Permission denied

Additional installations:

To make your machine somewhat more palatable, you might want to consider installing bash-completion:

# yum install -y bash-completion

You’ll also probably want to add the PolicyKit (polkit) .pkla file that I recommend in my earlier article. Typically that means adding something like:

[Allow james libvirt management permissions]
Identity=unix-user:james
Action=org.libvirt.unix.manage
ResultAny=yes
ResultInactive=yes
ResultActive=yes

as root to somewhere like:

/etc/polkit-1/localauthority/50-local.d/vagrant.pkla

Your machine should now be setup perfectly! The last thing you’ll need to do is to make sure that you get a Vagrantfile that does things properly! Here are some recommendations.

Shared folders:

Shared folders are a mechanism that Vagrant uses to pass data into (and sometimes out of) the virtual machines that it is managing. Typically you can use NFS, rsync, and some provider specific folder sharing like 9p. Using rsync is the simplest to set up, and works exceptionally well. Make sure you include the following line in your Vagrantfile:

config.vm.synced_folder './', '/vagrant', type: 'rsync'

If you want to see an example of this in action, you can have a look at my puppet-gluster Vagrantfile. If you are using the puppet apply provisioner, you will have to set it to use rsync as well:

puppet.synced_folder_type = 'rsync'

KVM performance:

Due to a regression in vagrant-libvirt, the default driver used for virtual machines is qemu. If you want to use the accelerated KVM domain type, you’ll have to set it:

libvirt.driver = 'kvm'

This typically gives me a 5x performance increase over plain qemu. This fix is available in the latest vagrant-libvirt version. The default has been set to KVM in the latest git master.

Dear internets!

I think this was fairly straightforward. You could probably even put all of these commands in a shell script and just run it to get it all going. What we really need is proper RPM packaging. If you can help out, that would be excellent!

If we had a version of vagrant-libvirt alongside a matching Vagrant version in Fedora, then developers and hackers could target that, and we could easily exchange dev environments, hackers could distribute product demos as full vagrant-libvirt clusters, and I could stop having to write these types of articles ;)

I hope this was helpful to you. Please let me know in the comments.

Happy hacking,

James

 


Keeping git submodules in sync with your branches

This is a quick trick for making working with git submodules more magic.

One day you might find that using git submodules is needed for your project. It’s probably not necessary for everyday hacking, but if you’re glue-ing things together, it can be quite useful. Puppet-Gluster uses this technique to easily include all the dependencies needed for a Puppet-Gluster+Vagrant automatic deployment.

If you’re a good hacker, you develop things in separate feature branches. Example:

cd code/projectdir/
git checkout -b feat/my-cool-feature
# hack hack hack
git add -p
# add stuff
git commit -m 'my cool new feature'
git push
# yay!

The problem arises if you git pull inside of a git submodule to update it to a particular commit. When you switch branches, the git submodule‘s branch doesn’t move along with you! Personally, I think this is a bug, but perhaps it’s not. In any case, here’s the fix:

add:

#!/bin/bash
exec git submodule update

to your:

<projectdir>/.git/hooks/post-checkout

and then run:

chmod u+x <projectdir>/.git/hooks/post-checkout

and you’re good to go! Here’s an example:

james@computer:~/code/puppet/puppet-gluster$ git checkout feat/yamldata
M vagrant/gluster/puppet/modules/puppet
Switched to branch 'feat/yamldata'
Submodule path 'vagrant/gluster/puppet/modules/puppet': checked out 'f139d0b7cfe6d55c0848d0d338e19fe640a961f2'
james@computer:~/code/puppet/puppet-gluster (feat/yamldata)$ git checkout master
M vagrant/gluster/puppet/modules/puppet
Switched to branch 'master'
Your branch is up-to-date with 'glusterforge/master'.
Submodule path 'vagrant/gluster/puppet/modules/puppet': checked out '07ec49d1f67a498b31b4f164678a76c464e129c4'
james@computer:~/code/puppet/puppet-gluster$ cat .git/hooks/post-checkout
#!/bin/bash
exec git submodule update
james@computer:~/code/puppet/puppet-gluster$

Hope that helps you out too! If someone knows of a use-case when you don’t want this functionality, please let me know! Many thanks to #git for helping me solve this issue!

Happy hacking,

James