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Month: July 2013

Migrated to WordPress

Migrated to WordPress

So, my site is now looking a little different from how it used to. I’ve actually changed how I’m hosting the service, completely. My original site was on Google Sites via my Google Apps account, but I’ve never really been satisfied with Google Sites and the limited control that was offered. So I took the plunge and got myself a “Droplet” on DigitalOcean, and installed WordPress.

The site may look different, but barring a couple of articles that I haven’t migrated yet (in particular, a couple of my old Anime Tierlist posts are still missing for now), all of the links from my previous site should still be active – either at the same location, or with a redirect. Please let me know if that’s not the case!

For the time being, my old Google Sites page will remain operational, but it will go away once I’m sure all content has been moved here.

Network UPS Tools (nut) and systemd

Network UPS Tools (nut) and systemd

Thanks to the Fedora developers, nut does actually ship some unit files for systemd. Unfortunately, those unit files provide a somewhat minimal functionality, with fairly fixed startup order and without taking advantage of systemd’s unit activation features. This caused some problems when I was building my new server a while back. This new machine is quite wicked fast with a quad-core IVB and an SSD—so fast, in fact, that systemd was starting nut’s UPS driver before the UPS itself was probed on the USB bus. As a result, startup failed quite badly, and it didn’t automatically recover.

So, obviously, we have to delay the startup of the nut driver until the USB device has been probed. But what about the other services? As it turns out, nut-server(upsd) and nut-monitor(upsmon) are actually perfectly happy to start up in any order with no more than a few warning messages in the logs as they wait for the other services to become available. So lets simplify the unit files for those. First, /etc/systemd/system/nut-server.service:

[Unit]
Description=Network UPS Tools - power devices information server

[Service]
ExecStart=/usr/sbin/upsd
Type=forking

[Install]
WantedBy=multi-user.target

If you have configured upsd to listen to a particular network interface or on a particular network address (in upsd.conf) it almost certainly needs the interface to be configured first; you should add in After=network.target.

Now, we can tweak the unit file for the monitoring process: /etc/systemd/system/nut-monitor.service:

[Unit]
Description=Network UPS Tools - power device monitor and shutdown controller
After=nut-server.service

[Service]
ExecStart=/usr/sbin/upsmon
PIDFile=/run/nut/upsmon.pid
Type=forking

[Install]
WantedBy=multi-user.target

I’ve left in the After=nut-server.service for only one reason: To reduce the warning messages in the log output when starting both upsd and upsmon on the same system. It’s not strictly required.

One thing to double-check: Ensure that the nut packages on your system have installed the file /usr/lib/systemd/system-shutdown/nutshutdown. This file doesn’t need any modifications, but it’s required to handle emergency poweroffs and test reboots correctly. It should look something like this, and it must be executable:

#!/bin/sh
/usr/sbin/upsmon -K >/dev/null 2>&1 && /usr/sbin/upsdrvctl shutdown

Now for the fun bit; handling starting up the nut driver for the USB UPS automatically once it’s been probed by the kernel. Ideally, we want to make this independent of things like which USB port it happens to be plugged into—this means creating a device file symlink with an appropriate stable name. Lets see what we have available…

# udevadm info --attribute-walk --name /dev/bus/usb/003/003

  looking at device '/devices/pci0000:00/0000:00:1a.0/usb3/3-1/3-1.1':
    KERNEL=="3-1.1"
    SUBSYSTEM=="usb"
    DRIVER=="usb"
[...]
    ATTR{idVendor}=="051d"
    ATTR{quirks}=="0x0"
    ATTR{serial}=="4B1111P37995  "
    ATTR{version}==" 1.10"
    ATTR{urbnum}=="13527"
    ATTR{ltm_capable}=="no"
    ATTR{manufacturer}=="APC"
    ATTR{removable}=="removable"
    ATTR{idProduct}=="0002"
    ATTR{bDeviceClass}=="00"
    ATTR{product}=="Back-UPS ES 550 FW:843.K2 .D USB FW:K2 "
[...]

I’ve stripped out a fair bit of the output, but as you can see we have some things to work with. The idVendor and idProduct will identify the device as a UPS, and the serial number will give a nice unique id for this UPS. Lets write a udev rule! I stuck it into the file /etc/udev/rules.d/53-nut-usbups-systemd.rules

ACTION!="add|change", GOTO="nut-usbups-systemd_rules_end"
SUBSYSTEM=="usb_device", GOTO="nut-usbups-systemd_rules_real"
SUBSYSTEM=="usb", GOTO="nut-usbups-systemd_rules_real"
SUBSYSTEM!="usb", GOTO="nut-usbups-systemd_rules_end"

LABEL="nut-usbups-systemd_rules_real"

ATTR{idVendor}=="051d", ATTR{idProduct}=="0002", TAG+="systemd", SYMLINK+="ups/$attr{serial}"

LABEL="nut-usbups-systemd_rules_end"

With this, my UPS is now available with device file /dev/ups/4B1111P37995. And since I’ve tagged it with “systemd”, we will be able hook it up to our systemd unit. In order to keep things matching up, I defined the driver in my ups.conf as follows:

[apc]
        driver = usbhid-ups
        port = auto
        serial = "4B1111P37995"

Ok, lets go and write the systemd unit file to start up the driver for my “apc” UPS device. I’m going to make use of another cool systemd feature here, template unit files and instances. Create a unit file named nut-driver@.service, with the following content:

[Unit]
Description=Network UPS Tools - power device driver controller

[Service]
ExecStart=/usr/sbin/upsdrvctl start %i
ExecStop=/usr/sbin/upsdrvctl stop %i
Type=forking

So far, so good! Now here’s the clever bit. Right now, systemd is exposing a unit for the device, but it’s using the name sys-devices-pci0000:00-0000:00:1a.0-usb3-3\x2d1-3\x2d1.1.device which is not only very ugly, but it’s also dependent on the usb path and port probe order. Lets create a unit with our new device name, in the file /etc/systemd/system/dev-ups-4B1111P37995.device:

[Unit]
Description=APC Back-UPS ES 550_FW

You don’t actually need any more in the file; systemd will handle hooking it up to the appropriate real device automatically. But now we can hook up our unit file to be automatically started when the ups becomes available:

# mkdir /etc/systemd/system/dev-ups-4B1111P37995.device.wants
# ln -s ../nut-driver@.service /etc/systemd/system/dev-ups-4B1111P37995.device.wants/nut-driver@apc.service

Note that in the symlink that was created, I’ve added the string “apc” after the @ sign. When the unit is started, this will be substituted for the %i in the nut-driver@ template unit file. This will cause the upsdrvctl command to look for the driver named “apc” in ups.conf, thus completing the chain and starting the the appropriate driver.

And now my UPS drivers reliably start, even when my computer can boot faster than USB can probe.

The unfortunate part is that a lot of this work is fairly system-specific. I’m not sure that it is all suitable for use in the upstream nut package, due to the customization required. I’d appreciate any comments or thoughts.

Release version 1.0.0! (And 1.0.1, you know, because)

Release version 1.0.0! (And 1.0.1, you know, because)

There is now an official release version (or two) of the image-id tool!

This release is the final result of both porting image-id to use the latest 2.0 API version of libmirage, and adding support for reading MCN and ISRC numbers from disc images. There is some work in progress that might allow these to be automatically submitted to musicbrainz using a future third-party tool.

The release notes and download files are available on the Github release page.

Note that 1.0.1 is a sort of brown-paper-bag release; I’d forgotten to pull before tagging. There is no reason for you to use 1.0.0; please go with 1.0.1 instead.

Summer 2013

Summer 2013

I have now rejoined the ranks of the anime-watching, I guess! Here’s the list of things that I care about in the upcoming season. Expect this page to change over the course of the season.

Just to note, this list is way absurdly too long. I wonder what I’m going to end up dropping.

Continued from last season

Wait, what, I actually watched things last season? Well, no, not really. But I went and marathoned a few shows to catch up.

New this season

  • Stella Women’s Academy, High School Division Class C3 – it has Makino Yui, And if I’ve learned anything from past shows like C -Control- or Sora o Kakeru Shoujo or Tsubasa Chronicles, that doesn’t mean very much. But it has at least one character with a voice actress I’m a fan of 🙂
  • NEW GENSHIKEN
  • Some more The World God Only Knows, too.
  • Fate/kaleid liner PRISMA ILLYA. There is no way this can not be awesome. It’s as if they’d made a third season of Nanoha. Possibly almost as good as a Tsukihime anime, should they have made one.

Things where I used to be more than a season behind and had to catch up first

  • The second season of the “Monogatari” series. I’m kind of surprised how far behind I am on this; I have to watch Nise- and Neko- (Black) to catch up before starting on this. Which is probably a good thing, because knowing SHAFT it’s not going to come out on schedule anyways. (I’m now caught up on the previous shows, but Crunchyroll has this on a delay…)
  • There’s new Rozen Maiden, but I haven’t seen any of the previous work. So, yeah. (I’ve now watched the entire first season, and have started this. It’s awesome!)

Things that aren’t actually from this season at all.

  • Captain Harlock
  • My Little Monster (Tonari no Kaibutsu-kun). Picked it at random, but it’s surprisingly sweet.

Things that I thought I wouldn’t watch, but upon further reflection changed my mind about

Things I’m probably definitely not watching

  • Fantasista Doll – it has surprisingly well-animated plaid skirts. But that’s about it.