Blog

  • postfix transport with smarthost

    Dear lazyyweb,

    Has anyone got a way for postfix to use a transport map such that it sends email to the given MX host for some specified domains then default to a smarthost for the remainder?

    The logic would be:

    IF domain in (‘example.net’, ‘foo.bar’,etc etc) THEN use the relevant MX host ELSE send to smarthost.isp.net

    i can use a transport map to send from specific domains to specific hosts, eg @domain.com goes to otherisp.net mailserver but not to just use domain.com’s MX hosts

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  • Careful with apache upgrades

    You might (or not if you don’t visit) notice all my websites were down.  A rushed apt-get dist-upgrade and I found two problems:

    1. PHP5 got removed, which is bad if you run a wordpress site that uses PHP to run
    2. The apache configuration has changed.

    Yes, the NEWS entries did warn me, if I read them fully. Yes, I didn’t read them enough.

    Apache now ignores configuration files that don’t end in .conf To give a completely non-theoretical example, if you have your virtual hosts in files such as /etc/apache2/sites-enabled/enc.com.au then this will not be recognised and your sites will show the default “It works” page.

    Stuff that doesn’t fall in the usual places where website stuff should go, which for my setup is a lot of things, will also be denied as the developers have tightened up the rules around what is permitted.  Pretty simple to fix with a few <Directory blah> clauses.

    This isn’t a criticism of the Debian apache developers. They do an awesome job of keeping the package workable, flexible but secure which isn’t easy.  Now it’s all back working, I actually agree with the changes they have made. It is just that the latest changes are, well, tricky so be forewarned.

     

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  • Step or Sloping Graphs

    Even though the backend of Rosenberg NMS uses rrdtool RRD files, the front end graphs are created using jqPlot.  The idea is to have a set of templates for the different types of graphs and just apply them to the various data sets.  It makes things a lot simpler for new graphs because you just select which one you want; unless you want something a lot different which would involve a new graph template.

    In any case, anyone that looks enough at the standard rrdtool graphs will know they are a series of steps. While it depends on the RRA, usually they are 5 minute steps, so a graph showing an increasing rate might show 5 minutes of 2 Mbps and then the next 5 minutes of 11 Mbps. jqPlot graphs as I’ve currently got them draws a line between two data points, so there would be a sloping line starting at 2.5 minutes (half of the first 5 minute interval) and 2Mbps sloping up to 11 Mbps at 7.5 minutes.

    At first I thought this was wrong and spent some time attempting to “fix” the graph by making it look like a rrdtool graph more. Someway through that process I stopped and wondered, what IS the right way? The answer like a lot of other things, is “it depends”.

    For a graph showing a rate, such as the output bits per second on an interface, the way this is done is at regular intervals a counter is measured. So if at time 0 the counter is 140 and time 60 the counter is 200 and finally at time 120 the counter is at 800 there has been an average rate of 1 [(200-140)/60] and 100 [(800-200)/60)]. rrdtool would show a horizontal bar at 1 bps and then another horizontal bar at 100 at the next time interval. jqPlot would show a sloping line going from 30,1 up to 90,100.

    Two graphs looking very different from the same data, what gives?  Each graph is right, or rather is showing an estimation of different things, hence their differences.

    rrdtool is showing the average rate for that time period. It is in some ways accurate because leaving aside missed wrap-arounds and resets that many bits did pass through that interface for the time specified.  However often the graphs are interpreted incorrectly as the real rate and not an average.  We can be reasonably sure for a rate that it would not be 1 for exactly a minute and then immediately jump to 100 for another minute.  This isn’t rrdtool’s fault, it is just how the graphs can be interpreted.

    jqplot will show more “realistic” graphs, with a curve sloping up. However this too makes assumptions that the rate increase is linear which often it is not. It just gives the illusion that the graph knows more about the data than it really does.

    In the end, both graphs are at the same time accurate and misleading. It’s important when looking at any graph in general (not just these two types) that you understand its limits and assumptions.  To give one example of the problems that can be missed, traffic interfaces may have microbursts (large amount of traffic in short amount of time) which, due to the averaging that goes on in graphing are invisible to graphs and give an incorrect account of what is going on.

     

     

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  • jqplot in Turbogears

     

    I’ve been working on the Rosenberg jqPlot GraphsNMS graphs slowly migrating them from using rrdtool graph and using jqplot.  While there have been many false-starts and re-works, I now have a working set of graphs, two of which are shown on the page.

    The graphs look a lot slicker and I have also simplified the admin screens.  I found I kept having to type the same thing in over and over for the rrdgraphs and have narrowed down the type of graphs to approximately 5.  They’re certainly not bulletproof and need more testing but they’re a good start.

    The graphs are based upon the ToscaWidgets2 series of widgets that then provide a nice “handle” for the jqPlot code.  My graphs even have some hand-coded Javascript to give nice units on the Y axis.

     

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  • First Look at RoseNMS screens

    More work has gone into the various GUI screens for RoseNMS. While still early days, these screenshots give an idea of the final program.

    Host Map

    The maps have been updated and now just use CSS for layout, rather than hard calculating the coordinates using javascript. This gives a cleaner and more fluid look to the maps. Hovering over the map item will show more details about the item. There are maps for hosts (shown) as well as attributes.

    Attribute View with information, graph and events
    Attribute View with information, graph and events

    Attribute details show some information about the attribute, the default graph and the events. Clicking on the more button above the graph takes you to the graph page for that attribute.

    Graphs

    Finally the graph handling is completely re-written with the concept of graph templates. These are basic types of graphs. The one shown is the basic “lines” template that shows… lines! Only things required are the RRD data source, the multiplier, the legend and how you want the units shown. From that the program builds all the required VDEFs and CDEFs.

  • props-ng 3.3.8

    Procps-ng 3.38 was released yesterday.  Besides the bug fixes,there have been two main enhancements: NUMA and systemd support.

    top comes with NUMA support which is a soft dependency, meaning that if compilied with the support, top will try to link at runtime to libnuma. The new key presses are ‘2’ and ‘3’ which will show the Nodes or more detail about a specific node respectively.

    ps has two new output columns; unit and uunit. These permit ps to display the systemd unit and user unit fields.  The systemd support is a
    hard dependency which is enabled with –with-systemd

     

    procps-ng is available from gitorious or sourceforge:

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  • RNMS on GitHub

    Rosenberg NMS is now found on GitHub at https://github.com/csmall/rnms

    The code is still pre-alpha but it is now available to try out.  This means you can try out this new network management system. I have done this to hopefully shake out some of the bugs before the first release.  The program has minimal documentation but does work, kinda.

     

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  • Removing itools

    Update: The newer code is now running, though still needs some testing.

    For very many years I have been running a set of tools on my website that basically runs whois or nslookup queries and presents them in a standard format.  I have decided today to shut this part of the website down as the code running those components is very old and I’ve not maintained it for years.  Back when I initially wrote the tools, in 1995 or so, there wasn’t many alternatives to this site but that has long changed.

    So thanks for those who emailled me over the years; its been an interesting journey.

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  • Pie Charts in TurboGears

    You might of looked at Ralph Bean’s tutorial on graphs and thought, that’s nice but I’d like something different.  The great thing about ToscaWidgets using the jqPlot library is that pretty much anything you can do in jqPlot, you can do in ToscaWidgets and by extension in TurboGears.  You want different graph types? jqPlot has heaps!

    My little application needed a Pie Chart to display the overall status of attributes. There are 6 states an attribute can be in: Up, Alert, Down, Testing, Admin Down and Unknown.  The Pie Chart would show them all with some sort of colour representing the status. For this example I’ve used hard-coded data but you would normally extract it from the database using a TurboGears model and possibly some bucket sorting code.

    I’ve divided my code into widget specific, which is found in myapp/widgets/attribute.py and the controller code found unsurprisingly at myapp/controllers/attribute.py  Also note that some versions of ToscaWidgets have a bug which means any jqPlot widget won’t work, version 2.0.4 has the fix for issue 80 that explains briefly the bug.

    The widget code looks like this:

    from tw2.jqplugins.jqplot import JQPlotWidget
    from tw2.jqplugins.jqplot.base import pieRenderer_js
    import tw2.core as twc
    
    class AttributeStatusPie(JQPlotWidget):
        """
        Pie Chart of the Attributes' Status """
        id = 'attribute-status-pie'
        resources = JQPlotWidget.resources + [
                pieRenderer_js,
                ]
    
        options = {
                'seriesColors': [ "#468847", "#F89406", "#B94A48", "#999999", "#3887AD", "#222222"],
                'seriesDefaults' : {
                    'renderer': twc.js_symbol('$.jqplot.PieRenderer'),
                    },
                'legend': {
                    'show': True,
                    'location': 'e',
                    },
                }

    Some important things to note are:

    • resources are the way of pulling in the javascript includes that actually do the work, generally if you have something like a renderer using js_symbol further on, it needs to be listed in the resources too.
    • seriesColors is how you make a specific data item a specific colour, or perhaps change the range of colours.  It’s not required if you use the default set, which is defined in the jqPlot options.
    • The renderer tells jqPlot what sort of graph we want, the line above says we want pie

     

    Next the controller needs to be defined:

    from myapp.widgets.attribute import AttributeStatusPie
    
    @expose('myapp.templates.widget')
        def statuspie(self):
            data = [[
                    ['Up', 20], ['Alert', 7], ['Down', 12], ['Admin Down', 3], ['Testing', 1], ['Unknown', 4],
                    ]]
            pie = AttributeStatusPie(data=data)
            return dict(w=pie)

    And that is about it, we now have a controller path attributes/statuspie which shows us the pie chart.
    My template is basically a bare template with a ${w.display | n} in it to just show the widget for testing.

    Pie Chart in Turbogears
    Pie Chart in Turbogears

     

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  • procps-ng 3.3.7 Released

    procps-ng version 3.3.7 was released today.  It has some new and interesting features in the top program that Jim has been busy working on.  There is a new filter feature which can exclude fields that match a value for example. The remainder of the changes are small bug fixes and getting the compile warnings count down with -Wall enabled. The library revision was updated but this did not involve an API or ABI change.

    procps-ng can be downloaded off the sourceforge page which has the current and previous releases stored there. Alternatively you can visit our gitorious page if git fetch is more your thing. Debian packages will be going into experimental until the freeze is over and we get things unblocked.