Archive for December, 2009

Start Virtual NICs on OpenSolaris Boot

Wednesday, December 23rd, 2009

One of the more frustrating things I deal with on OpenSolaris is that every time I reboot, I have to manually bring up each virtual network interface in order to start all of my zones. There is a bug report for this problem that says a fix will be integrated into b132, which is just a few weeks away, but in the mean time, I’ve whipped up an SMF service to handle this for me. Create a file vnic.xml:

<?xml version="1.0"?>
<!DOCTYPE service_bundle SYSTEM "/usr/share/lib/xml/dtd/service_bundle.dtd.1">

<service_bundle type='manifest' name='vnic'>

<service
    name='network/vnic'
    type='service'
    version='1'>

    <dependency
        name='network_service'
        grouping='require_all'
        restart_on='none'
        type='service'>
        <service_fmri value='svc:/network/service' />
    </dependency>

    <dependent
        name='network_vnic'
        grouping='optional_all'
        restart_on='none'>
        <service_fmri value='svc:/system/zones' />
    </dependent>

    <exec_method
        type='method'
        name='start'
        exec='/usr/sbin/dladm up-vnic ${SMF_FMRI/*:/}'
        timeout_seconds='60' />

    <exec_method
        type='method'
        name='stop'
        exec=':true'
        timeout_seconds='60' />

    <property_group name='startd' type='framework'>
        <propval name='duration' type='astring' value='transient' />
    </property_group>

    <stability value='Unstable' />

    <template>
        <common_name>
            <loctext xml:lang='C'>
            Virtual Network Interface
            </loctext>
        </common_name>
        <documentation>
            <manpage title='dladm' section='1M'
                manpath='/usr/share/man' />
        </documentation>
    </template>
</service>

</service_bundle>

This service should run sometime after the network is started but before the zones are started. Load it in with svccfg -v import vnic.xml and create an instance of the service for each of the VNICs that you want to start. For example, if you want to start vnic0 on boot:

# svccfg -s vnic add vnic0
# svcadm refresh vnic0
# svcadm enable vnic0

UPDATE: Build 132 is out an this functionality has been integrated as the svc:/network/datalink-management:default service. The services that were added above can be removed by running svccfg delete vnic.

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Watching Network Connections with DTrace

Monday, December 14th, 2009

DTrace is one of those magical tools that I sort of know how to use but never had the chance to. Usually, firing up truss is sufficient to figure out what’s happening in a process.

But recently, a team at GWU was setting up a web application and having some problems. It would hang whenever it was accessed. The application is highly modular and accesses several other servers for resources, so I suspected there must have been some sort of network problem, probably a blocked firewall port somewhere. Unfortunately, the application produces no logs (!) so it was pretty much guesswork.

I started snoop to watch for traffic generated by the application. I knew from watching the production application that there should be communication between two servers over port 9300, but I wasn’t seeing anything. I thought of using truss to determine if the application was at least trying to connect, but being a web application, the process was way too short-lived to attach to. Even if I was able to attach to it, all I might have learned was that the application was calling the ‘connect’ system call and possibly getting a return value.

DTrace, on the other hand, doesn’t have to attach to a particular process. It just sits in the kernel and dynamically observes what your scripts tell it to. It also has the ability to look into data structures so you can actually see what values are passed to functions and system calls. I used this ability to watch every call to the connect system call.

#!/usr/sbin/dtrace -qs

syscall::connect:entry
{
        socks = (struct sockaddr*) copyin(arg1, arg2);
        hport = (uint_t) socks->sa_data[0];
        lport = (uint_t) socks->sa_data[1];
        hport <<= 8;
        port = hport + lport;

        printf("%s: %d.%d.%d.%d:%d\n", execname, socks->sa_data[2], socks->sa_data[3], socks->sa_data[4], socks->sa_data[5], port);
}

This script copies arg2 bytes from the address pointed to by arg1 into kernel space and uses the data to determine the port (big endian order) and destination address.

When run, the script immediately revealed that the web application was trying to connect to itself rather than a database server, a simple configuration mistake made difficult to diagnose due to poor logging facilities in the application.

In the future, there will be a network provider for DTrace which will simplify the job of extracting data from network calls. It should then be possible to rewrite the script to simply:

#!/usr/sbin/dtrace -qs

tcp:::connect-request
{
        printf("%s: %s:%d\n", execname, args[2]->ip_daddr, args[4]->tcp_dport);
}

Hopefully I’ll have more opportunities to use DTrace in the future.

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Posted in System Administration | 1 Comment »

Music Player Daemon on OpenSolaris

Friday, December 4th, 2009

MPD is essential software for me. It’s one of the few music players out there for Unix that does gapless playback and ReplayGain. It’s also nice that, because it’s a daemon, I’m not bound to any particular interface. Fortunately, there is a really good one in the form of Sonata.

MPD is not included in OpenSolaris yet, so last weekend I built some packages for it. The build has been stable for me and I’m happy with the state of the packages so I thought I’d share them. First add my package repository:

$ pfexec pkg set-authority -O http://pkg.thestaticvoid.com:10000/ thestaticvoid

MPD

This package and its dependencies require OpenSolaris 2009.06 or newer. Install it by typing pfexec pkg install mpd. The following formats are supported:

$ mpd -V
...
Supported decoders:
[mad] mp3 mp2
[vorbis] ogg oga
[oggflac] ogg oga
[flac] flac
[audiofile] wav au aiff aif
[faad] aac
[mp4] m4a mp4
[mpcdec] mpc
[wavpack] wv

Supported outputs:
shout null fifo ao solaris httpd 

Supported protocols:
file:// http://

I plan on adding ffmpeg support soon which will add support for even more codecs.

To run MPD, create a configuration file in your home directory like

port                    "6600"
music_directory         "~/music"
playlist_directory      "~/.mpd/playlists"
db_file                 "~/.mpd/mpd.db"
log_file                "~/.mpd/mpd.log"

Create any directories from the configuration file that don’t exist, such as ~/.mpd/playlists and start the daemon by running mpd ~/.mpdconf as your user. It will immediately build a library of your music.

Alternatively, mpd can be run system-wide, which just seems more appropriate to me for whatever reason. The only complicated part about this is that you have to give MPD permission to write to the audio device. Edit /etc/logindevperms, find the /dev/sound/* lines and change the mode to 0666 so that they look like:

/dev/console    0666    /dev/sound/*        # audio devices
/dev/vt/active  0666    /dev/sound/*        # audio devices

Logout and log back in for the settings to take effect. Then modify /etc/mpd.conf to your liking and start the daemon by typing svcadm enable mpd. You may have to svcadm refresh manifest-import for SMF to load the mpd manifest.

mpdscribble

I also built a package for mpdscribble which is a mature, well-maintained scrobbler for Last.fm. Install it by typing pfexec pkg install mpdscribble. Set your Last.fm or Libre.fm username and password in /etc/mpdscribble.conf and start the daemon with svcadm enable mpdscribble. That’s all there is to it.

Sonata

Sonata is a lightweight cilent for MPD. Looks pretty nice too:

Sonata

Because Sonata requires Python 2.5, and OpenSolaris 2009.06 only really supports Python 2.3, this package requires build 127 or newer. Install it by typing pfexec pkg install sonata. It can be launched from the Applications->Sound & Video menu.

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Posted in Desktop | 2 Comments »