snapd-generated systemd units cause etckeeper with bzr backend to fail

[James Tait]

I use etckeeper to track changes to my /etc/ directory for easy rollback, backup and traceability. I use the bzr backend, because it's the supported VCS I'm most familiar with. Since installing snapd and the ubuntu-core and ubuntu-calculator-app snaps, bzr has been failing to commit the new systemd units generated for those snaps:

bzr: ERROR: bzrlib.errors.InvalidEntryName: Invalid entry name: snap-ubuntu\x2dcalculator\x2dapp-5.mount

Traceback (most recent call last):
  File "/usr/lib/python2.7/dist-packages/bzrlib/commands.py", line 930, in exception_to_return_code
    return the_callable(*args, **kwargs)
  File "/usr/lib/python2.7/dist-packages/bzrlib/commands.py", line 1121, in run_bzr
    ret = run(*run_argv)
  File "/usr/lib/python2.7/dist-packages/bzrlib/commands.py", line 673, in run_argv_aliases
    return self.run(**all_cmd_args)
  File "/usr/lib/python2.7/dist-packages/bzrlib/commands.py", line 697, in run
    return self._operation.run_simple(*args, **kwargs)
  File "/usr/lib/python2.7/dist-packages/bzrlib/cleanup.py", line 136, in run_simple
    self.cleanups, self.func, *args, **kwargs)
  File "/usr/lib/python2.7/dist-packages/bzrlib/cleanup.py", line 166, in _do_with_cleanups
    result = func(*args, **kwargs)
  File "/usr/lib/python2.7/dist-packages/bzrlib/builtins.py", line 842, in run
    no_recurse, action=action, save=not dry_run)
  File "/usr/lib/python2.7/dist-packages/bzrlib/mutabletree.py", line 52, in tree_write_locked
    return unbound(self, *args, **kwargs)
  File "/usr/lib/python2.7/dist-packages/bzrlib/mutabletree.py", line 453, in smart_add
    adder.add(file_list, recurse=recurse)
  File "/usr/lib/python2.7/dist-packages/bzrlib/mutabletree.py", line 764, in add
    inv_path)
  File "/usr/lib/python2.7/dist-packages/bzrlib/mutabletree.py", line 628, in _add_one_and_parent
    file_id=file_id)
  File "/usr/lib/python2.7/dist-packages/bzrlib/inventory.py", line 2234, in make_entry
    return factory(file_id, name, parent_id)
  File "/usr/lib/python2.7/dist-packages/bzrlib/inventory.py", line 422, in __init__
    super(InventoryFile, self).__init__(file_id, name, parent_id)
  File "/usr/lib/python2.7/dist-packages/bzrlib/inventory.py", line 222, in __init__
    raise errors.InvalidEntryName(name=name)
InvalidEntryName: Invalid entry name: snap-ubuntu\x2dcalculator\x2dapp-5.mount

bzr 2.7.0 on python 2.7.11 (Linux-4.4.0-21-generic-x86_64-with-
    Ubuntu-16.04-xenial)
arguments: ['/usr/bin/bzr', 'add', '-q', '.']
plugins: bash_completion[2.7.0], builddeb[2.8.6], bzrtools[2.6.0],
    changelog_merge[2.7.0], colo[0.4.0], etckeeper[unknown], grep[2.7.0],
    launchpad[2.7.0], netrc_credential_store[2.7.0], news_merge[2.7.0],
    pipeline[1.5.0], po_merge[2.7.0], qbzr[0.23.1], search[1.7.0dev],
    weave_fmt[2.7.0], webdav[1.12.2], xmloutput[0.8.8]
encoding: 'utf-8', fsenc: 'UTF-8', lang: 'en_GB.UTF-8'

*** Bazaar has encountered an internal error. This probably indicates a
    bug in Bazaar. You can help us fix it by filing a bug report at
        https://bugs.launchpad.net/bzr/+filebug
    including this traceback and a description of the problem.
etckeeper warning: bzr add failed

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: snapd 2.0.2
ProcVersionSignature: Ubuntu 4.4.0-21.37-generic 4.4.6
Uname: Linux 4.4.0-21-generic x86_64
ApportVersion: 2.20.1-0ubuntu2
Architecture: amd64
CurrentDesktop: Unity
Date: Wed Apr 27 12:50:27 2016
InstallationDate: Installed on 2014-07-04 (662 days ago)
InstallationMedia: Ubuntu 14.04 LTS "Trusty Tahr" - Release amd64 (20140417)
SourcePackage: snapd
UpgradeStatus: Upgraded to xenial on 2016-04-25 (2 days ago)

[Samuele Pedroni (pedronis)]

afaiu those units have such names because systemd mandates that format, also they are managed by snapd, as workaround wouldn't a .bzrignore or some etckeeper level equivalent help?

[James Tait (jamestait)]

Possibly, yes, but is that desirable? I suppose these files are worthless without the corresponding files in /var/lib/snapd/snaps?

If that's the case, maybe this bug should be reassigned to etckeeper, which seems to manage the list of ignored files itself and not export a way for other packages to add to that list. I'd be willing to be there are other packages that generate similar files.

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[JP Vossen (jp-jpsdomain)]

The hack-around in https://bugs.launchpad.net/ubuntu/+source/bzr/+bug/1035045/comments/3 "worked" for me with `etckeeper` + BZR on Mint-18, in that it stopped the error messages. I don't actually know or care what omitting the affected snap files in `/etc/` might do later.

Note I needed 2 lines in `/etc/.bzrignore` and was confused when the first line failed to work. And you probably also need to:
```
# Be root
cd /etc
sudo vi .bzrignore
 systemd/system/snap*
 systemd/system/multi-user.target.wants/snap*
bzr rm --keep systemd/system/snap* systemd/system/multi-user.target.wants/snap*
etckeeper commit 'Ugly hack-around for bzr/etckeeper errors for snapd use of backslash in file names'
```

[John Lenton (chipaca)]

I'm setting the bug task of snapd to invalid, as it's not snapd's bug if etckeepter falls over because snapd creates files named in a way required by systemd.