I've been busy lately trying to learn more about Docker. I'm not much of a fan of "application containers" and still prefer a full-blown "distro container" like that provided by LXC (good) or OpenVZ (better)... but I have to admit that the disk image / layering provided by Docker is really the feature everyone loves... which provides almost instantaneous container creation and start-up. If OpenVZ had that, it would be even more awesome.
OpenVZ certainly has done a lot development over the past couple of years. They realized that simfs just wasn't cutting it and introduced ploop storage... and then made that the default. ploop is great. It provides for instant snapshots which is really handy for doing zero-downtime backups. I wonder how ploop differs these days from qcow2? I wonder how hard it would be to add disk layering features like Docker to OpenVZ with ploop snapshots?
Applications Containers In the Beginning
Ok, so Docker has taken off but I really can't figure out why. I mean Red Hat introduced OpenShift some time ago. First it was a service, then a product, and lastly a open source product that you can deploy yourself if you don't need support. A couple of years ago I attended an OpenShift presentation and at that time it provided "Gears" which were basically chrooted processes with a custom SELinux policy applied... and cgroup resource management? Something like that. While (non-OpenVZ) containers don't contain, with the SELinux added, OpenShift gears seemed to be secure enough.
OpenShift offered easy deployment via some git-based scheme (if I remember correctly) and a bunch of pre-packaged stacks, frameworks, and applications called "cartridges" which I see as functionally equivalent to the Docker registry.. It didn't have the disk image layering and instant startup of Docker so I guess that's was a minus.
These days I guess OpenShift is going to or has shifted to using Docker.
Docker Crawls Before It Can Walk
Docker started off using aufs but that was an out-of-tree filesystem that isn't going to make it into mainline. Luckily Red Hat helped by adapting Docker to use device mapper-based container storage... and then btrfs-based container storage was added. What you get as default seems to depend on what distro you install Docker on. Which of the three is performant and which one(s) sucks... again that depends on who you talk to and what the host distro is.
Docker started off using LXC. I'm not sure what that means exactly. We all know that LXC is "LinuX native Containers" but LXC seems to vary greatly depending on what kernel you are running and what distro you are using... and the state of the LXC userland packages. Docker wised up there and decided to take more control (and provide more consistency) and created their own libcontainer.
The default networking of Docker containers seems a bit sloppy. A container gets a private network address (either via DHCP or manually assigned, you pick) and then if you want to expose a service to the outside world you have to map that to a port on the host. That means if you want to run a lot of the same service... you'll be doing so mostly on non-standard ports... or end up setting up a more advanced solution like a load balancer and/or a reverse proxy.
Want to run more than one application / service inside of your Docker container? Good luck. Docker was really designed for a single application and as a result a Docker container doesn't have an init system of its own. Yeah, there are various solutions to this. Write some shell scripts that start up everything you want... which is basically creating your own ghetto init system. That seems so backwards considering the gains that have been made in recent years with the switch to systemd... but people are doing it. There is something called supervisor which I think is a slight step up from a shell script but I don't know much about it. I guess there are also a few other solutions from third-parties.
Due to the complexity of the networking and the single-app design... and given the fact that most web-services these days are really a combination of services that are interconnected, a single Docker container won't get you much. You need to make two or three or more and then link them together. Links can be private between the containers but don't forget to expose to the host the port(s) you need to get your data to the outside world.
While there are ways (hacks?) that make Docker do persistent data (like mapping one or more directories as "volumes" into the container or doing a "commit"), Docker really seems more geared toward non-persistent or stateless use.
Because of all of these complexities, which I really see as the result of an over-simplified Docker design, there are a ton of third-party solutions. Docker has been trying to solve some of these things themselves too. Some of Docker's newer stuff has been seen by some (for example CoreOS) as a hijacking of the original platform and as a result... additional, currently incompatible container formats and tools have been created. There seems to be a new third-party Docker problem solver start-up appearing weekly. I mean there are a ton of add-ons... and not many of them are designed to work together. It's kind of like Christianity denominations... they mostly believe the same stuff but there are some important things they disagree on. :)
Application Containers Are Real
Ok, so I've vented a little about Docker but I will admit that application containers are useful to certain people... those into "livestock" virtualization rather than "pet" virtualization aka "fleet computing". Those are the folks running big web-services that need dozens, hundreds or thousands of instances of the same thing serving a large number of clients. I'm just one one of those folks so I prefer the more traditional full-distro style of containers provided by OpenVZ.
Working On Fedora 22
I've already blogged about working on my own Fedora 22 remix but I've also made a Fedora 22 OpenVZ OS Template that I've submitted to contrib. Yeah, it is pre-release but I'll update it over time... and Fedora 22 is slated for release next week unless there are additional delays.
Like so many OpenVZ OS Templates my contributed Fedora 22 OS Template doesn't have a lot of software installed and is mainly for use as a server. For my own use though I've added to that with the MATE desktop, x2goserver, Firefox, LibreOffice, GIMP, Dia, Inkscape, Scribus, etc. It makes for a pretty handy yet light desktop environment. It was a little tricky to build because adding any desktop environment will drag in NetworkManager which will overpower ye 'ole network service and break networking in the container upon next container start. So while building it "vzctl enter" access from the OpenVZ host node was required. With a handful of systemctl disable / mask commands it was in working order again. Don't forget to change the default target back to multi-user from graphical... and yeah, you can turn off the display manager because you don't need that since x2go is the access method of choice.
BTW, there was a libssh update that broke x2go but they should have that fixed RSN.
Multi-purpose OS Templates
I also decided to play with LXC some on my Fedora 22 physical desktop. I found a libvirt-related recipe for LXC on Fedora. Even though it was a little dated it was very helpful.
The yum-install-in-chroot method of building a container filesystem really didn't work for me. I guess I just didn't have a complete enough package list or maybe a few things have changed since Fedora 20. I decided to re-purpose my Fedora 22 OpenVZ OS Template. I extracted it to a directory and then edited a few network related files (/etc/sysconfig/network, removed /etc/sysconfig/network-scripts/ifcfg-venet*, and added an ifcfg-eth0 file). I also chroot'ed into the directory and set a root password and created a user account that I added to the wheel group for sudo access.
After a minute or so for the minor modifications (and having left the chroot'ed environment) I did the virt-install command to create a libvirt managed LXC container using the new Fedora 22 directory / filesystem... and bingo bango that worked. I also added some GUI stuff and just like with OpenVZ I had to disable NetworkManager or it broke networking in the container. Anyway... running an LXC container is a like OpenVZ on a mainline kernel... just without all of the resource management and working security. Baby steps.
Containers Taken Too Far?
While hunting down some videos on Docker I ran into RancherVM. What is that? To quote from their description:
RancherVM is a new open source project from Rancher Labs that makes it simple to run KVM inside a Docker container.
What they heck? Run KVM VMs inside of Docker containers? Why would anyone want to do that? Well, so you can embed KVM VM disk images inside of Docker images... and easily deploy a KVM VM (almost) as easily as a Docker container. That kind of makes my head hurt just thinking about running a Windows 7 Desktop inside of a Docker container... but someone out there is doing that. Yikes!
Thanks to Vlada Catalic for translating this article into Bosnian.
I would consider myself an unlikely Linux ambassador. Not that I hide any Linux use or fascination but that I am not out there on a mission to encourage or convert people to Linux. Mostly it would be an occasional conversation about me using Linux for something or a conversation where I am explaining that there are more operating systems then just Windows or OS X. Most of the time my Linux conversations are with those that already have some connection to Linux. To be honest I have probably been a much bigger "Ambassador" to LibreOffice than to Linux; and I am not an uber LibreOffice or ODF fan boy but one that believes for most basic users it will work just fine without all the Microsoft expense. All of that has taken a slight detour within the past couple of weeks.
At the end of April I was finally able to do something "geeky" by attending LinuxFest Northwest (check box in the 'ol geek bucket list). It's not that the sessions where so enlightening or life altering that I have been sending up Linux smoke signals from the Bridger mountains or anything like that; although they were informative and enjoyable. Nor was I overpowered and brain washed by the four guys I carpooled with for the 14'ish hour drives. Although we did have some good conversations some regarding Linux and some regarding Open Source issues, and to say none of it has had an influence on any of my views would be untrue. I did come back from LinuxFest Northwest with a more renewed interest in Linux and have been using Fedora now almost exclusively outside of work. I also returned with what I consider some cool SWAG. Now it's the SWAG that's the most important thing of all right? I came back with a nice black Fedora t-shirt that I thought fellow carpooler dowdle was going to mug me for, a beanie with GNU printed on it from the Free Software Foundation that I purchased, and a hippie looking acid dyed t-shirt promoting Linux and LinuxFest Northwest 2015 which I also purchased. I have been intentionally wearing them when I can.
My first "Ambassador" moment came when my oldest boy asked me about the GNU printed on my beanie. This gave me an opportunity, as well as a challenge, to explain to an almost 9 year old what GNU meant within the context of the Free Software Foundation. This included the discussion of locked down proprietary software and the negatives of such as well as the pro's of software that is open and free to improve or be fixed. In addition to my oldest son being in the car with me I also had two of my other boys one of which was listening to the conversation intently as well.
My second "Ambassador" moment came about on a quick trip to Walmart. I was once again wearing my GNU beanie. I was in the produce area and walked near a Latino family whose dad looked in my direction. Shortly thereafter his family passed by me and as he did he looked at me, smiled, and said "GNU huh?" and kept walking. Now it is certainly possible he thought my beanie was promoting the Wildebeest but I like to think he knew it was in reference to Free Software.
The third and most recent "Ambassador" moment once again took place at my local Walmart store a little after eleven at night. This time I was wearing my "Peace, Love and Linux", LinuxFest Northwest t-shirt. I had just finished checking out at one of the self checkout stations and ended up having a conversation with gentleman named Keith (we exchanged names as we parted ways). Keith saw my shirt and asked me if I used Linux which turned into a nice conversation. Now Keith knew of Linux and knew of OpenOffice but that was probably all. It's even possible Keith had an experience long ago or perhaps he has just read about Linux and OpenOffice but beyond that I would say Keith was someone that probably had some degree of interest in Linux. He asked me the usual questions of how easy or hard it was to install these days and where could a person get Linux, did you have to look on eBay? I told him he could just download it from the distribution's website. Told him briefly about the DistroWatch website which a person could find links to the actual distributions websites. I told him most users probably used Ubuntu or some derivative of Ubuntu or they probably used Fedora. I told him either one should install and work just fine on most hardware. He asked about OpenOffice which led to a discussion of OpenOffice and the origins of LibreOffice and which one was probably the best to use and how most distributions most likely included it by default. I even explained how LibreOffice was also available for Windows and OS X too. All in all it was an enjoyable conversation that lasted several minutes and ended in a hand shake and the exchanging of names. Keith also verified a couple of times the names of the two distributions (Ubuntu & Fedora) I had recommended. Now I have no idea if Keith will actually try installing Linux or try using LibreOffice. Nor do I know if he will have a good experience or a bad experience if he does decide to try using Open Source software. What I do know is that because I simply wore an article of clothing promoting Linux, Keith saw an opportunity to express an interest in something to someone that might be able to answer questions and provide some first hand feedback.
I have never really found a way to "get involved" with a project before as I am not a coder, have no deep comprehension of the inner workings of Linux, nor do I feel I would make a good candidate for documentation writing. This wasn't a bad way to get involved and to be honest it was a lot easier and more enjoyable then attempting to submit a bug report.
Here is a preview video of the upcoming Fedora 22 release (running in a KVM VM). This is my personal remix (with non-Fedora provided rpmfusion-free packages, google-chrome-stable, and flash-plugin added) and I haven't bothered with the branding nor customization at all... and I don't really publicly distribute it.. but I'd be happy to share my kickstart file if anyone wants it.
In the video I show the install process, and then show all of the desktop environments that are pre-installed which include... GNOME 3.16.1, Plasma 5.3.0, LXQT 0.10, MATE 1.10, XFCE 4.12.1, and Cinnamon 2.4.8. Enjoy!
Please Note: The official Fedora live media always automatically logs the liveuser in... but on my personal remix I haven't bothered to set that up so I have to put in "liveuser". Again, the Fedora media is NOT like that.
Checkpoint and Restore In Userspace is a project I'm very interested in as it is associated with OpenVZ and will be used in the upcoming EL7-based OpenVZ kernel branch... which was recently released in beta. The FLOSS Weekly folks have two developers on from the project. Enjoy!
BTW, Kir gave me (and Donnie) a brand spanking new CRIU tee-shirt at LFNW. Thanks Kir!
Must get moose and squirrel!
Author George Dyson contrasted the Hollywood movie "The Imitation Game" with reality.
Emily Dunham, OSU Open Source Lab's Student Systems Engineer, provided an introduciton to Git and GitHub.
Michael "Monty" Widenius, CTO of the MariaDB Foundation, discussed new features in MariaDB 10.1.
Alex Juarez, Rackspace's Principal Engineer Linux Support, discussed troubleshooting beyond ps and top.
Seth Schoen, Senior Staff Technologist at the Electronic Frontier Foundation in San Francisco, discussed the upcoming Let's Encrypt project... fast and free SSL/TLS certificates for your servers.
There are a few bad spots in the video that I attribute to an SDcard going bad... and yeah, there is some hiss in the audio (internal mic rather than a wireless one)... but overall, very watchable. Enjoy!