To get old behavior, add a .gitattributes containing: * annex.backend=WORM
I feel that SHA256 is a better default for most people, as long as their
systems are fast enough that checksumming their files isn't a problem.
git-annex should default to preserving the integrity of data as well as git
does. Checksum backends also work better with editing files via
unlock/lock.
I considered just using SHA1, but since that hash is believed to be somewhat
near to being broken, and git-annex deals with large files which would be a
perfect exploit medium, I decided to go to a SHA-2 hash.
SHA512 is annoyingly long when displayed, and git-annex displays it in a
few places (and notably it is shown in ls -l), so I picked the shorter
hash. Considered SHA224 as it's even shorter, but feel it's a bit weird.
I expect git-annex will use SHA-3 at some point in the future, but
probably not soon!
Note that systems without a sha256sum (or sha256) program will fall back to
defaulting to SHA1.
get, drop: Added --auto option, which decides whether to get/drop content
as needed to work toward the configured numcopies.
The problem with bundling it up in optimize was that I then found I wanted
to run an optmize that did not drop files, only got them. Considered adding
a --only-get switch to it, but that seemed wrong. Instead, let's make
existing subcommands optionally smarter.
Note that the only actual difference between drop and drop --auto is that
the latter does not even try to drop a file if it knows of not enough
copies, and does not print any error messages about files it was unable to
drop.
It might be nice to make get avoid asking git for attributes when not in
auto mode. For now it always asks for attributes.
First, this ensures that git annex addurl, when run repeatedly with the
same url, doesn't create duplicate files, which it did before when it
fell back to the longer filename.
Secondly, the file part of an url is frequently not very descriptive on its
own.
The uri scheme, auth, and port is intentionally left out, as clutter.
Backends are now only used to generate keys (and check them); they
are not arbitrary key-value stores for data, because it turned out such
a store is better modeled as a special remote. Updated docs to not
imply backends do more than they do now.
Sometimes I'm tempted to rename "backend" to "keytype" or something,
which would really be more clear. But it would be an annoying transition
for users, with annex.backends etc.
get not honoring --from has surprised me a few times, so least surprise
suggests it should just behave like copy --from. This leaves the difference
between get and copy being that copy always requires the remote to copy
from, while get will decide whether to get a file from a key/value store or
a remote.
In particular, munge key filenames to comply with the IA's filename limits,
disable encryption, support their nonstandard way of creating buckets, and
allow x-amz-* headers to be specified in initremote to set item metadata.
Still TODO: initremote does not handle multiword metadata headers right.
You do not need to pull from a remote to make git-annex aware of it.
Pulling only makes git know about remote/master branches, but git-annex
does not care about that. When git-annex encounters a remote in .git/config
that has no recorded annex.uuid, it connects to it to get the uuid
automatically, and will immediately start using it.
A later part of this walkthrough shows how to pull from a remote
in order to get its location tracking info, so that git-annex can retrieve
files from it. That's the right place to document the need to pull from
a remote periodically.
