Ubuntu Wiki

   1 [12:59] <james_w> hello everyone
   2 [12:59] <james_w> who is here for the packaging training session?
   3 [12:59] <bac> good morning james_w
   4 [13:00]  * Rail is
   5 [13:00] <mr_spot_> i am
   6 [13:01] <james_w> we'll give it a couple of minutes for others to roll in
   7 [13:01] <james_w> but everyone should check that they have debhelper installed
   8 [13:02] <james_w> we are going to be looking at manpages and examples from the package
   9 [13:02] <james_w> also, you should check that you have debhelper >= 7 :-)
  10 [13:03] <james_w> if you are still on hardy then you will need to grab it from backports
  11 [13:07] <james_w> right, let's get started
  12 [13:07] <james_w> hello everyone
  13 [13:07] <james_w> my names is James Westby and I will be your host today
  14 [13:07] <james_w> please feel free to shout out questions at any time
  15 [13:07] <maxpaguru> hello!
  16 [13:07] <james_w> we'll try and stay on topic to start with, and hopefully we'll have some time at the end for general questions
  17 [13:08] <james_w> but there's always lots of helpful people in #ubuntu-motu
  18 [13:08] <james_w> so feel free to jump in there with general questions
  19 [13:08] <james_w> so, debhelper, what is it?
  20 [13:09] <james_w> if you open /usr/share/doc/debhelper/examples/rules.arch you can see an example debian/rules using debhelper
  21 [13:09] <james_w> it is a Makefile that is used to build the package
  22 [13:09] <james_w> all of the dh_* commands are provided by debhelper to do common tasks
  23 [13:10] <james_w> e.g., to clean the build tree it does:
  24 [13:10] <james_w> clean:
  25 [13:10] <james_w>         dh_testdir
  26 [13:10] <james_w>         dh_testroot
  27 [13:10] <james_w>         rm -f build-stamp
  28 [13:10] <james_w>         # Add here commands to clean up after the build process.
  29 [13:10] <james_w>         #$(MAKE) clean
  30 [13:10] <james_w>         #$(MAKE) distclean
  31 [13:10] <james_w>         dh_clean
  32 [13:10] <james_w> so it calls dh_testdir, which checks this is an unpacked Debian source package
  33 [13:10] <james_w> dh_testroot which checks the command is being run as root
  34 [13:11] <james_w> then runs any clean target for the thing being packaged
  35 [13:11] <james_w> and finally calls dh_clean that does some standard cleaning stuff
  36 [13:11] <james_w> there are lots of dh_* commands that do lots of useful things
  37 [13:12] <james_w> all are designed to do nothing if they don't apply though, the idea being that running one shouldn't do any damage if it doesn't apply to your package
  38 [13:12] <james_w> .
  39 [13:12] <james_w> .
  40 [13:12] <james_w> lots of packages have rules files that look fairly similar to the above
  41 [13:12] <james_w> with just small changes for the package
  42 [13:13] <james_w> this means that they can be fairly repetitive
  43 [13:13] <james_w> also, because there are lots of commands listed it's hard to see what the unusual things are, which makes review and learning harder
  44 [13:14] <james_w> therefore debhelper v7 was invented, to help with some of these issues
  45 [13:14] <james_w> .
  46 [13:14] <james_w> ..
  47 [13:14] <james_w> the basic idea behind debhelper v7 is that you say "give me a default package", and then make tweaks where you need to
  48 [13:15] <james_w> this leads to the example rules file being like /usr/share/doc/debhelper/examples/rules.tiny
  49 [13:15] <james_w> I'll paste it here as it is so small
  50 [13:15] <james_w> #!/usr/bin/make -f
  51 [13:15] <james_w> %:
  52 [13:15] <james_w>         dh $@
  53 [13:15] <james_w> .
  54 [13:15] <james_w> .
  55 [13:16] <james_w> quite a bit simpler isn't it?
  56 [13:16]  * weboide agrees
  57 [13:16] <binarymutant> very simple
  58 [13:17] <maxpaguru> simple
  59 [13:17] <james_w> but...
  60 [13:17] <james_w> it's also not very clear what is happening
  61 [13:17] <james_w> when you see this you should think "simple, default, boring package"
  62 [13:17] <james_w> does nothing special
  63 [13:18] <james_w> the "%:" means whatever target
  64 [13:18] <james_w> and the "dh $@" means just have "dh" do its default thing for that target
  65 [13:19] <james_w> with "dh" being a new command in debhelper v7
  66 [13:19] <james_w> .
  67 [13:19] <james_w> .
  68 [13:20] <james_w> what dh does is run through a list of commands for the specific target and execute each in turn
  69 [13:20] <james_w> so for the clean example above it will first run "dh_testdir", then "dh_testroot" etc.
  70 [13:21] <james_w> where it will try everything that makes sense in that target
  71 [13:21] <james_w> making use of the fact that debhelper commands do nothing if they don't apply to the package
  72 [13:21] <james_w> .
  73 [13:21] <james_w> .
  74 [13:21] <james_w> but, we have a bit of a problem
  75 [13:22] <james_w> what does it do in the clean target for running the clean target of the thing being packaged?
  76 [13:22] <james_w> that could in theory be anything
  77 [13:22] <james_w> .
  78 [13:22] <james_w> .
  79 [13:22] <james_w> what it does is run a command called "dh_auto_clean"
  80 [13:23] <james_w> quoting from its manpage:
  81 [13:23] <james_w>        dh_auto_clean is a debhelper program that tries to automatically clean up after a package build. If there’s a Makefile and it contains a
  82 [13:23] <james_w>        "distclean", "realclean", or "clean" target, then this is  done by running make (or MAKE, if the environment variable is set). If there is a
  83 [13:23] <james_w>        setup.py or Build.PL, it is run to clean the package.
  84 [13:23] <james_w> .
  85 [13:23] <james_w> .
  86 [13:23] <james_w> so it knows what to do for the most common systems
  87 [13:24] <james_w> if there's a common system that isn't covered then you can propose a patch to that command to add it
  88 [13:24] <james_w> there is similarly and dh_auto_build and dh_auto_install
  89 [13:24] <james_w> plus dh_auto_configure and dh_auto_test
  90 [13:24] <james_w> they all work in a similar manner
  91 [13:24] <james_w> .
  92 [13:25] <james_w> .
  93 [13:25] <james_w> what do you do if your package isn't common though?
  94 [13:25] <james_w> in that case you need to run a custom command instead of the dh_auto_ command
  95 [13:25] <james_w> how do you tell debhelper to do that?
  96 [13:25] <james_w> .
  97 [13:25] <james_w> .
  98 [13:26] <james_w> here's where you use a bit of magic :-)
  99 [13:27] <james_w> if you define a new target in debian/rules with a special name then you can run what you like instead
 100 [13:27] <james_w> if you add
 101 [13:27] <james_w> override_dh_auto_clean:
 102 [13:27] <james_w> then debhelper will run that target instead of dh_auto_clean
 103 [13:28] <james_w> so, to run a "./clean" script instead of "$(MAKE) clean" then you can put
 104 [13:28] <james_w> .
 105 [13:28] <james_w> override_dh_auto_clean:
 106 [13:28] <james_w>         ./clean
 107 [13:28] <james_w> .
 108 [13:28] <james_w> in debian/rules
 109 [13:30] <james_w> so, when you open the debian/rules file you can see "default package, except that it does something special for clean"
 110 [13:31] <james_w> this works for all dh_* commands as well, so if you need to do something special when installing manpages you could write
 111 [13:31] <james_w> override_dh_installman:
 112 [13:31] <james_w>         dh_installman
 113 [13:32] <james_w>          ln -s debian/tmp/usr/share/man/foo.1 debian/tmp/usr/share/man/do_foo.1
 114 [13:32] <james_w> .
 115 [13:32] <james_w> or similar
 116 [13:32] <james_w> (and with correct indentation :-)
 117 [13:33] <james_w> any questions so far?
 118 [13:34] <bac> james_w: so there is a default target which we can override for all of the dh_* tools?
 119 [13:35] <james_w> yep, to override dh_foo, add a target "override_dh_foo:"
 120 [13:36] <james_w> and if you have really obscure needs you can still add a "clean:" target and run all the commands you need there
 121 === clive is now known as Guest54207
 122 [13:41] <james_w> if you want to look at some real packages then you can run
 123 [13:41] <james_w> grep-dctrl "debhelper (>= 7" -F Build-Depends < /var/lib/apt/lists/*_Sources
 124 [13:41] <james_w> for a likely list
 125 [13:42] <james_w> anything else anyone would like to know about the new debhelper?
 126 [13:43] <weboide> james_w: How can we upgrade packages to dh 7 ?
 127 [13:43] <james_w> good question
 128 [13:43] <maxb> What about needing to override phases differently for binary-arch and binary-indep targets?
 129 [13:43] <james_w> the first thing to do is increase the build-dependency on debhelper
 130 [13:44] <james_w> then you need to edit your rules file, find anything that is not just running and dh_* command
 131 [13:44] <james_w> you can convert them to override_ rules
 132 [13:45] <james_w> then delete the rest and add the "dh" calls
 133 [13:45] <james_w> make sense?
 134 [13:45] <weboide> it does, thanks
 135 [13:46] <james_w> maxb: could you give an example of what you mean?
 136 [13:46] <maxb> uh, sure, whilst I hunt for it: How about mentioning --with quilt ? :-)
 137 [13:48] <james_w> maxb: what does that do?
 138 [13:48] <weboide> james_w: I think he wants to know how to integrate quilt/dpatch into a dh7 rules file. (or Im wrong)
 139 [13:49] <maxb> Ah.... the short version is that it enables various additional handling for a quilt-based package built into the dh7 lifecycle - but I don't know more than that, and was hoping you could tell me! :-)
 140 [13:50] <james_w> :-)
 141 [13:51] <maco> there's also dh_quilt_patch and dh_unquilt_patch
 142 [13:52] <james_w> ok, got it :-)
 143 [13:52] <james_w> "dh --with quilt" means use the quilt "addon"
 144 [13:52] <james_w> so if you do this and build-depend on a recent enough version of quilt, then debhelper will load the quilt "addon"
 145 [13:53] <Laney> %:
 146 [13:53] <Laney>   dh --with quilt $@
 147 [13:53] <Laney> easy!
 148 [13:53] <james_w> you can find this addon in /usr/share/perl5/Debian/Debhelper/Sequence/quilt.pm
 149 [13:53] <james_w> (if you are on Jaunty or later I think)
 150 [13:53] <weboide> neat, thanks :)
 151 [13:53] <maco> (quilt 0.46-7 or newer)
 152 [13:53] <Laney> I think that's only in karmic
 153 [13:53] <james_w> which pretty much says run "dh_quilt_unpatch" before clean, and "dh_quilt_patch" before configure
 154 [13:54] <james_w> so it will automatically do the quilt things at the right time
 155 [13:54] <maco> Laney: dh7 is only in karmic too, though isn't it?
 156 [13:54] <Laney> nah, that's in Jaunty (maybe not the override stuff?)
 157 [13:54] <james_w> I'm not sure if there are dpatch of simple-patchsys addons as well
 158 [13:54] <weboide> maco: I have debhelper >= 7 in jaunty, but don't have the dh_quilt stuff
 159 [13:54] <james_w> intrepid has 7
 160 [13:54] <james_w> but as Laney says, the override stuff is slightly newer than the first release of 7
 161 [13:55] <Laney> maco: rmadison debhelper
 162 [13:55] <maxb> override is present as of 7.0.50, requiring karmic
 163 [13:56] <james_w> you can read more in "man dh"
 164 [13:56] <james_w> and http://kitenet.net/~joey/blog/entry/cdbs_killer___40__design_phase__41__/
 165 [13:57] <james_w> (which shows the original way of doing overrides, which was not nearly as nice)
 166 [13:57] <james_w> http://kitenet.net/~joey/blog/entry/debhelper_dh_overrides/
 167 [13:58] <james_w> so, get using it! :-)
 168 [13:59]  * weboide likes dh7!
 169 [13:59] <james_w> we're out of time for today
 170 [13:59] <james_w> if you have any questions then head on over to #ubuntu-motu
 171 [13:59] <maxb> To rephrase my previous question - how do you run conditional logic that must be run only when building the arch-indep packages - i.e. not on the non-i386 buildds - example, a Python module that splits its arch-specific and arch-indep files
 172 [13:59] <james_w> ah, yeah, sorry maxb
 173 [14:00] <james_w> I'm not sure to be honest :-)
 174 [14:00] <maxb> Not a problem, and I'm happy to take this to after-session discussion in #ubuntu-motu :-)
 175 [14:01] <james_w> yeah, let's head there
 176 [14:01] <james_w> thanks everyone
 177 === txwikinger2 is now known as txwikinger_work
 178 [14:02] <stvo> thx
 179 [14:02] <maxpaguru> Thanks. bye :-)
 180 [14:03] <mr_spot_> thanks james :D
 181 [14:03] <weboide> thank you for this session james_w
 182 [14:04] <james_w> np