Planet on Chris Irwin

Sharing Host Files With KVM

Tue, 10 Mar 2020 23:06:27 -0400

Adventures with sharing host files with a KVM VM using 9p and libvirt with SELinux.

Discard (TRIM) with KVM Virtual Machines... in 2020!

Mon, 09 Mar 2020 18:10:33 -0400

While checking out some logs and google search analytics, I found that my post about Discard (TRIM) with KVM Virtual Machines has been referenced far more than I expected it to be. I decided to take this opportitnity to fact-check and correct that article.

Push It To the Limit #3

Sat, 24 Jun 2017 01:07:39 +0000

If you’re considering trying out autocross, I say go for it. I’m very new, and have found people at the two events I’ve attended (WOSCA #1, and PITL #3) to be friendly and extremely helpful.

Additionally, you can do it with your own car. You don’t need some sort of special race-spec track beast. Both events have also had loaner helmets available (although I spent $200 and bought my own helmet meeting the appropriate standards).

Highlight Reel

Tue, 18 Apr 2017 02:39:39 +0000

Goal

I want to combine a few clips together, with a 5-seconds of intro text on each one.

Create overlay text in GIMP

I created some overlay text in gimp, then exported to png files. An example (Note the transparancy, and drop shadow):

Trim clips to length

Using the methods I’ve described in previous ffmpeg posts, I trimmed the clips, ensuring that there is at least five seconds of lead-in on each clip for the text.

ZigZag Volvo

Mon, 17 Apr 2017 02:38:31 +0000

While driving through New York on my way to the Watkins Glen 2017 opening weekend, I encountered a nut in a Volvo zig-zagging through highway traffic. I decided use ffmpeg yet again (I’m starting to wonder if OpenShot would actually bring anything to the table at this point, besides crashing)

Plan

I want a video with the rear camera until the Volvo passes, then the front camera after. I want to use the front audio for the whole video.

ffmpeg part three - No more Boogaloos to give

Mon, 17 Apr 2017 02:26:05 +0000

Just like the first two times, I’m assembling my Watkins Glen 2017 track footage with ffmpeg.

However, I encountered a small issue I didn’t last year, plus I decided to change things up a bit with codecs, and audio selection.

ffmpeg requires protocol whitelist now

I’m using pretty much the same concatenation command as last year (filenames are a bit different):

$ for f in Front-*MOV; do echo file "$f"; done | ffmpeg -f concat -i - -c copy Front.MOV

The error I got from ffmpeg looked like:

Using Metadoctor on HP/Palm WebOS Devices

Thu, 15 Sep 2016 01:45:12 +0000

My Devices

I decided to update the 3/4 of my Palm WebOS devices. The Pre (not pictured) and Pre2 (middle) were my primary, daily-driver phones for over two years, from September 2009 through to spring 2012, when I acquired a Galaxy Nexus and made the jump to Android.

The Pre3 (right) I also picked up on eBay. It came in box, with all accessories, and a spare battery.

WebOS in 2016

Wed, 14 Sep 2016 21:52:46 +0000

Note: Yes, WebOS Technically still exists. However, this article isn’t talking about the TV OS version made by LG.

While this article was actually written to discuss getting Palm devices usable, I felt some preamble was necessary.

My Palm History

I’ve got a soft spot for Palm. My first PDA was the Palm Vx, possibly the greatest PDA ever made. Easily get days of battery from a device that can store all your calendar and contacts information, synchronizing periodically with your master copy on your computer.

Snapperd on Fedora with SELinux enabled

Wed, 14 Sep 2016 21:46:01 +0000

Snapper is an excellent utility that provides hourly snapshots of btrfs subvolumes.

Fedora ships with selinux enabled by default. This is excellent, and shouldn’t be disabled. To allow this, most software in Fedora has appropriate rules defined, including snapper.

However, snappers rules only allow it to work on / and /home. If you wish to use it to snapshot /mnt/data, or /srv, or any other particular path, you’re going to have a very bad time.

ffmpeg part two - Electric Boogaloo

Wed, 20 Apr 2016 00:34:27 +0000

I just attended the Watkins Glen opening day for the second year. It was, again, a blast.

I made some slight adjustments to my ffmpeg assembly procedure from last year.

Dashcam saves video in 5-minute chunks

Instead of creating .list files, I simply used a pipe as input:

for fo in AMBA091*; do echo file "$fo"; done \
    | ffmpeg -f concat -i - -c copy Front-Track1.mov

Front and Rear videos need to be combined

Much like last year, I made short samples to confirm if any offsets needed to be done. However, I decided to move the video to the bottom-right corner to cover the timestamps, since they were incorrect on some videos (well, correct. Just not for this time zone)

Intel GPU Scaling mode

Tue, 19 Apr 2016 01:04:12 +0000

I was attempting to run my laptop at a lower resolution than the laptop panel. However, by default the video is scaled to fill the panel. This causes the image to be distorted (fonts look bad, etc).

On Linux (with Xorg, anyway), this behaviour can be tweaked with xrandr:

$ xrandr --output LVDS1 --set "scaling mode" "Center"

This is not a persistent setting, which is fine for my purposes.

My failed experiment with CalDAV/CardDAV

Sun, 17 Jan 2016 02:57:23 +0000

In an ongoing quest to attempt to lessen my Google dependancy, I decided to self-host my Calendar and Contacts using Baïkal.

Installing and configuring Baïkal is sufficiently documented elsewhere. This post is a 9somewhat short) account of why I’m giving up on self-hosted contacts and calendars.

Google

The problems can be summed up into these bullet points:

It is assumed (and practically required) to use Google Play Store
Google Play Store requires a Google Account
Google Account means you have Mail, Calendar, and Contacts

Simply adding your google account into your phone causes Mail, Calendar and Contacts to sync. Mail you can disable, and use an alternate client, as that data is housed internally to the gmail app, and not exposed system wide for other apps to use.

AWStats from multiple hosts

Sun, 18 Oct 2015 13:49:06 +0000

I decided I wanted some stats. There are a few options: Use a service (Google Analytics, etc) or parse your logs. Both have pros and cons. This article isn’t supposed to help you decide.

I just wanted simple stats based on logs: It’s non-intrusive to visitors, doesn’t send their browsing habits to third parties (other than what they send themselves), and uses the apache log data I’ve already got for the entire year.

Discard (TRIM) with KVM Virtual Machines

Sat, 17 Oct 2015 20:19:56 +0000

Update - March 09 2020

Since writing this article, I’ve made a few observations:

More people read this than expected
QEMU has since added discard support to the standard virtio disk, avoiding the need to use virtio-scsi
It kinda sorta works out of the box.

I’ve written a brief followup: Discard (TRIM) with KVM Virtual Machines… in 2020!

Original Article

I’ve got a bunch of KVM virtual machines running at home. They all use sparse qcow2 files as storage, which is nice and space efficient – at least at the beginning.

Multiple Instances of Gnome Terminal

Tue, 06 Oct 2015 12:00:05 +0000

Gnome 3 introduced a very handy feature, grouping multiple application windows (whether they be separate instances or not) into a single desktop icon. This means when <alt+Tab>ing through your windows, you can skip over the dozen firefox windows, then dive into just your terminal windows. Generally, this works great, and I think most users don’t have any issues.

However, some people (myself included) use a lot of terminals. Some are temporary short-lived generic terminals. Others are long-lived running mail (mutt), or a main development session. Unfortunately, trying to switch to my email terminal can be cumbersome as I squint at thumbnails of 10+ other terminals.

Video assembly with ffmpeg

Thu, 23 Apr 2015 01:19:00 +0000

I recently took my car to a racetrack, covered with cameras. I wanted to post these on youtube, but encountered a few issues:

Dashcam saves video in 5-minute chunks
Front and Rear videos need to be combined
I don’t know anything about video editing
I didn’t have a working video editor
Fedora doesn’t seem to ship ffmpeg, and rpmfusion doesn’t support Fedora 22 yet

The last point was somewhat resolved by a binary build of ffmpeg.

Living with BTRFS

Mon, 13 Apr 2015 23:56:00 +0000

This is the contents of a presentation I gave to KWLug in April 2015, roughly converted to blog format. The slides are available. ~~I’ll update this post with a link to the kwlug.org podcast when it goes online.~~ Audio and Video available via kwlug.org.

I didn’t get through all of the points, I barely touched on snapshots (and didn’t cover any utilities). I’ll post a follow-up with my filesystem corruption demonstration instructions.

Note that I am not a filesystem developer, just a user who isn’t afraid to experiment and share the lessons learned. If there are any comments/corrections, email me at chris -at- chrisirwin.ca

Adding a dependency into upstream-supplied systemd units

Mon, 09 Mar 2015 01:14:39 +0000

I recently restarted all my VMs at once and found that several managed to start services before they finished mounting their NFS shares. These shares back apache virtualhosts, mysql databases, and ultimately left several services in non-functional states. Systemd has the ability to depend on services (Requires=, and others) as well as filesystems (RequiresMountsFor=). However, I don’t want to modify or replace the .service files installed from the package. I’d have to manually reconcile changes during updates, and it just generally isn’t nice.

Recovering a deleted file (on btrfs)

Fri, 16 Jan 2015 04:35:09 +0000

So you might find yourself saying this one day:

HELP! I just deleted a file on my btrfs! It wasn’t old enough to be in a backup, snapshot, or git It was old enough that I don’t want to retype it. How do I get it back? Also, my btrfs is on an SSD, and it might kick off a garbage collection routine at any time!

Well, as luck would have it, I just did that to a blog post I’ve spent all evening writing.

Fedora Cloud Image on Linode

Fri, 16 Jan 2015 04:08:46 +0000

Linode offers pre-assembled Fedora VMs, but their environment doesn’t support SELINUX. You also don’t get any notification on when you should reboot for new kernels, etc.

I decided to attempt to adapt Fedora’s stock cloud image on Linode. It was not without it’s own effort, but ultimately I think it’s a better solution than attempting to retro-fit the linode image for booting. Also, I’m using the fedora cloud image on all my other VMs, so I’m familiar with how it’s set up (and can easily spool up a local copy for testing).

SELinux and apache (httpd)

Thu, 15 Jan 2015 03:54:27 +0000

I’ve just built a new web server vm, basically identical to my mariadb one, and the fedora cloud image. This is documentation on how I configured it, as well as the ttrss update daemon.

To get nfs to work, install nfs-utils. I need some packages also for ttrss.

$ yum install nfs-utils httpd php php-mysql php-mbstring php-xml

I’m putting the web root on an nfs mount from my nas. I have multiple virtualhosts.

SELinux and mariadb (mysql)

Thu, 15 Jan 2015 03:28:41 +0000

I’ve just built a new mysql server vm, using the instructions I posted previously. This is documentation on how I configured it.

To get nfs to work, install nfs-utils.

$ yum install nfs-utils httpd mariadb mariadb-server

I’m putting the database on an nfs mount from my nas. Socket files can’t exist on nfs. It’s easier to move the data than the socket file (I think I hit an selinux issue with socket access).

Fedora cloud for mere mortals

Thu, 15 Jan 2015 03:05:56 +0000

I’ve come across a post by Marek Goldmann detailing the basics of running Fedora cloud images on kvm. I found it was a massive help, but only got me part-way toward what I wanted.

The documentation for cloud-init is sub-par from what I can find, so I thought I’d post this with my own modifications.

My requirements were:

Easy scriptable deployment (Marek’s script got me 100% of this goal)
Static (sequential) IP assignments instead of DHCP
hostname != KVM domain name, making system replacements easier

Additionally, I changed some logic

Offlineimap repeatedly deleting All Mail

Thu, 28 Feb 2013 01:58:00 +0000

or “That’s why you read changelogs”

I was having some significant difficulties with offlineimap after upgrading to 6.5.4 (I’m using Ubuntu currently, so I upgraded straight from 6.3.4).

The original issue was a FolderValidity error, which is covered by the offlineimap FAQ. This affected my “All Mail” folder (It also affected my “Sent Mail”, but it got lost in the noise of the 67964 messages in All Mail). The recovery process is simply to remove that folder (and it’s sync history), and start over. Unfortunate, but fine. That’s why I’ve got a 28Mbit connection, after all.

Workaround for conflict between gnome-shell and vmware-player

Tue, 07 Feb 2012 11:37:00 -0800

I recently got a new machine for work, with lots of fancy memory and everything. First thing to do was install a friendly operating system with gnome-shell, and set up a VM for my windows/office requirements at work.

Normally I would favour Virt-Manager+kvm, but since we’re now using vmware-server (and soon vsphere hypervisor) I thought it would be better to keep compatible. Luckilly, vmware has a free player that works pretty well for my basic needs.

Review: Logitech Trackman Wheel Optical

Sat, 18 Dec 2010 23:55:00 -0800

As well as my previously mentioned Unicomp keyboard, I also decided to purchase a Logitech Trackman Wheel Optical. It’s basically a thumb-oriented trackball that resembles a standard mouse (with regards to clicking, scrolling, etc).

Adjusting to using the trackball was extremely easy. I have one at work and one at home. I haven’t been able to use it for games yet, so I’ve still got a second mouse around for that (more on that in a bit…)

Using devtodo with multiple projects

Mon, 12 Jul 2010 15:34:29 -0700

I’ve tried (and failed) to use many different pieces of software designed to manage todo lists. The main reasons I’ve failed is because the software either has a high learning curve, bad documentation, or it is cumbersome to use.

I’ve finally struck gold with devtodo. Out of the box, it is almost perfect, but there are a few little issues:

It expects .todo in the current directory
It has no ability to track what you are working on.

I’ve managed to work around both of those with some extra functions in my .bash_profile.

Reverse Find

Mon, 12 Jul 2010 14:54:00 -0700

I recently had need to do a reverse find, and couldn’t discover any programs that offer this functionality. I decided to work around the issue using a bash function, loops, and find.

This function can be stuffed into your ~/.bash_profile, and referenced wherever you need it.

rfind()
{
    rfind_path=&quot;${PWD}&quot;
    while [[ &quot;${rfind_path}&quot; != &quot;/&quot; ]]; do
        rfind_search_paths=&quot;${rfind_search_paths} ${rfind_path}&quot;
        rfind_path=$(dirname &quot;${rfind_path}&quot;)
    done
    
    find ${rfind_search_paths} / -maxdepth 1 $@ -print -quit
}

As an example, let’s say I’m in /home/user/docs, and I execute rfind somefile.txt. rfind will actually build a command and execute the following: