On Tue, Jul 12, 2005 at 05:23:39PM +0300, Steve McIntyre wrote: >At Debconf we've had a couple of very good discussion sessions about >changes that are wanted/needed in debian-cd. Firstly we had several >members of the debian-cd team thrash out what we wanted to do for the >next version, then a second chat with some more of the debian-cd users >to see what they would like us to do for them. I came to Debconf with >some ideas of my own for discussion, and several of these other people >have thrown extra things into the pot. Here's a summary of what we >came up with; I'll follow up to debian-cd with more details. Please >follow up there if you have comments or would like to get involved. And now, the more detailed version: 1. Re-structuring We need to refactor the code; the top-level Makefile is a mess, and there are far too many hacks in the codebase that make it impossible to maintain Some top-level wrapper scripts could make some of the common jobs much easier. At the moment, making a custom netinst CD (for example) is _hard_, even for the people using debian-cd every day. 2. Tasks The current code to maintain the tasks that go on the CDs is messy. We must generate the task list each time, rather than use the pre-gen lists from CVS. An easy way to check that tasks have been fulfilled in a CD build would be very useful, like we currently try to do with debootstrap. Includes/excludes should be much clearer. Hooks to add tasks at the right place would be considered useful by CDD developers, to allow lots more flexibility to control the layout of CD sets. 3. Dependencies I'm going to merge in the JTE patches, and add a dependency on the mkisofs-jte package. Also, I'm going to turn more of the current recommends/suggests into dependencies. It's not funny to build CDs and make a set that don't have boot graphics, or won't boot on mips, etc. On the Recommends/Suggests front, we need to check that the requisite packages are installed before starting a build. Also, we want to make the _packaged_ debian-cd more useful. At the moment, most serious users use the CVS version and their own patches, which is not ideal. 4. Code management CVS is too limiting. After some discussion we think that svn is probably the best choice, with svk for patch management. 5. More intelligence in debian-cd A debian-cd run should have more of an idea of what its target is. At the moment, we simply have to rely on the size of the target image in a few places. There are several places where knowing exactly if we're working on a DVD or CD would be very useful. 6. Actual layout of the CDs could be better At the moment, we guess how much space the docs/boot/tools etc. will take at the start of each CD run, then ask apt to fill up the available space. Then we run apt-ftparchive to generate the Packages and Sources files. This is not very accurate - a lot of the time during past releases has been taken up by manually juggling CD sizes to make them as large as possible without going over 650MB. A much better way would be to check sizes as each file is copied into the temporary tree, and Packages and Sources files generated by copying stanzas in to match. By keeping careful track of how much space the tree takes, once the tree gets to within a small margin of the target, we can start running mkisofs -print-size to check exactly how large the resulting image would be. It will even be possible to maximise the image size by simply running until a package/source file would take the image over the configured limit, then rolling back. This would also allow easier customisation of CDs - with some effort, custom CDs with extra packages should be feasible by adding the new packages to the list, and rolling back at the end of the build process to remove any trailing packages that no longer fit. An extra mode for image sizing (but _NOT_ image creation) may allow us to generate CD/DVD jigdo files directly from the archive metadata without actually reading in the .deb files at all. This will not be too hard to write support for, BUT will create jigdo files that do NOT contain MD5 sums. 7. Multi-arch (and optionally source) discs The new layout method should also make mixed discs easy, e.g. single DVDs for i386, amd64 _and_ the source for all the packages. Simply add the appropriate arch binaries and sources as part of the process of filling the disc tree. It's also possible to make CDs/DVDs that boot on multiple arches, and that might be very useful. On the binary & source front, this would make it possible to create standalone CDs that meet all source requirements. A little extra effort may be needed to make sure that things like syslinux source make it onto the CD. 8. Running without a local mirror A common complaint is that debian-cd basically requires a local mirror to be useful. This is not ideal for many end users, who may be trying to create small custom CDs and don't have the disk space for all the Debian packages needed. It should be feasible to make debian-cd work with remote mirrors, grabbing just the pieces it needs. This _may_ need custom work, or it may be possible to use one of several packages suggested to create a partial mirror. I'm actually leaning more towards custom code, perhaps even some tweaks to pipe the data into mkisofs as it is needed to save local disk. 9. Are business card ISOs actually useful? Compared to the netinst and other CDs, they depend much more on the software in the mirror exactly matching the code on the CD, which make them _much_ more fragile. Sizing them to fit on the BC CD media is also much more difficult. Do people still think the effort to create these is useful? 10. Signed release files The new functionality in apt for checking signatures on Release files is a good step on the road to better security. However, the CD builds by necessity have to generate new Packages and Sources files on each disc. This means that we have to also generate new Release files, which currently are not signed. Signing these would be good, possibly with a new key held on the machine(s) building official images. Similarly to the current apt code, if the Release file on the CD is not signed with a known-good key then the user should be presented with a message checking that they want to trust the CD. Customised CDs could contain new keys, then apt would ask the user to verify the fingerprint before adding it to the trusted list. 11. CD errata package After the recent problems with the first attempt at the sarge CD/DVD release, lots of discussion happened about ways to make CD/DVD mistakes less likely to happen. More testing always helps, but even then it's possible for bugs to slip through. Phil suggested that there could/should be an errata package created on our website somewhere (suggested: release.d.o/CD/$dist/errata.deb). As one of the last steps as a machine installs for the first time, it should ask the user, then check if there is an errata package available. If so, this package will download and (where possible) apply fixes to the new installation. Another simpler option would be to simply have an HTML page listing the errata, and instructions for the user to follow to fix their installation. Alternatively, an errate package could be pushed into the archive so that all installations might get it, not just those from CD. My own personal favourite would be the simple HTML file, but I think some discussion of the options here would be useful. -- Steve McIntyre, Cambridge, UK. firstname.lastname@example.org Is there anybody out there?
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