RFC: Comfy - a CLI framework to bring the Ubuntu cloud feeling to snappy Ubuntu Core

[Dustin Kirkland]

Alexander,

Can we get these moved over to a Google Docs spreadsheet at this
point?  Something that we can collaborate and edit more efficiently
than inline email, as we nail down the final set...

Oh, and having spent a couple of hours today working on a snappy
package, hitting a couple of snappy bugs, I must say that pastebinit
is absolutely *essential* for Comfy :-)

Cheers,
Dustin

Dustin Kirkland
Canonical, Ltd.


On Wed, Jan 28, 2015 at 11:13 PM, Scott Moser <scott.moser at canonical.com> wrote:
> On Tue, 13 Jan 2015, Alexander Sack wrote:
>
>> Good morning all,
>>
>> we have been asked a few times about adding one or another tool to
>> ubuntu-core to help you get your job done.
>>
>> To avoid making ubuntu-core overly heavy, what we thought we could put
>> together a cli tool framework called 'comfy' that would bring the
>> comfort and goodness we all learned to love from the default Ubuntu
>> cloud install to snappy Ubuntu Core.
>>
>> We have looked into that and came up with an annotated diff of the
>> packages in our core vs. cloud image as a starting point for a wider
>> discussion on our mailing lists.
>>
>> The raw diff we used as a starting point to come up with the list
>> below is in this paste: http://paste.ubuntu.com/9719652/.
>>
>> Please let us know if you feel something is missing or we currently
>> have marked with 'Y' shouldn't be in such comfy framework. So here it
>> is....
>
> Replying to the top message in the thread, because I'm suggesting
> something that might take this in a different way entirely.
>
> I absolutely agree with the motivation behind 'comfy'.  I have a set of
> cloud-init user-data that runs on all new instances and gives me some sane
> set of tools.
>
> It seems to me that the question:
>   what function is comfy?
> Is not all together much different from:
>   what should be in Ubuntu Server by default.
>
> After selecting this set of packages, we then have to manage to "snappify"
> them all, and I don't think we have a magic bullet for that yet.  As
> this package list grows, we all think "oh my... another package that we
> have to maintain a relocatable build for".
>
> Essentially, we have a *small* set of packages in Ubuntu Core (basically the
> minimum we can get by with), and a *huge* set of packages in Ubuntu that
> we'd like to magically be able to use whenever we need them.  We also have
> a nice way of getting the package and its dependencies in 'apt-get' or
> 'debootstrap'.
>
> We've assumed that packages have to be re-built to run on top of a snappy
> base.  They have to relocate themselves to no longer access files in / but
> rather /apps/<app-name>/<version>/.
>
> What if we relocated the *small* set, rather than the *huge* set?
>
> If we could make the set of packages in snappy limit themselves to a small
> set of paths, say: /snappy-core/{bin,lib,usr,var}
> then we could run applications in a container with '/snappy-core' mounted
> in.  The applications would live on the filesystem still under
> /apps/<app-name> but whenever they were run, they'd think that
>   /apps/app-name/lib was /lib
>   /apps/app-name/bin was /bin
>
> Then, creating (and maintaining) the ubuntu-server package set, or any
> product you can get to build and install and run on ubuntu, means just
> taking a tarball of that environment, and we already create those tarballs
> for lxc consumption.
>
> This is not significantly different than coreos's approach
>   https://coreos.com/docs/cluster-management/debugging/install-debugging-tools/
> they essentially let you get tools like 'tcpdump' by running a fedora
> container that has those nice tools.
>
> The issue with that approach, is that if your run a full container that
> has '/lib', then you can't get to your "real /lib".  So you can't run (or
> use) any of the programs or libraries that came with snappy.
>
> My suggestion is to move the "real /lib" to /snappy/lib, and then the
> container can have access to the entire filesystem without collisions.
> When you run 'snappy' that is provided by ubuntu core, you'll pick it up
> out of /snappy/bin the loader that loads it will be
> /lib64/ld-linux-x86-64.so.2 .
>
> What if, instead of assuming we have to make the *huge* relocate the
> *huge* set of packages
>
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