Is there a simple way to “git describe” a remote repository?

Question

I want to execute the following command on a remote server:

git archive --prefix="$tag/" --remote="ssh://$gitserver/var/git/$repo" "$tag" | tar -xvf-

The problem is I don't know what $tag is. It should be the output of git describe --abbrev=0 on an up-to-date clone, but I don't know how to get that information without making a local clone of the repository. Is it possible to do this without making a local clone?

Answer 1

The only way you could start parsing for your tag, without adding too much to your local disk, would be:

• make an empty repo
• add the remote address of your remote repo
• try a git fetch --dry-run

That will load the pack files of the remote repo, though.
I don't think you can just query this information without downloading something.

I have done it for a gitolite repo for instance:

VonC@NETVONC /c/prog/git
$ git init g2
Initialized empty Git repository in c:/prog/git/g2/.git/

VonC@NETVONC /c/prog/git
$ cd g2

VonC@NETVONC /c/prog/git/g2 (master)
$ git remote add origin https://github.com/sitaramc/gitolite.git

VonC@NETVONC /c/prog/git/g2 (master)
$ git fetch --dry-run
remote: Counting objects: 5114, done.
remote: Compressing objects: 100% (1919/1919), done.
remote: Total 5114 (delta 3548), reused 4664 (delta 3142)
Receiving objects: 100% (5114/5114), 1.81 MiB | 722 KiB/s, done.
Resolving deltas: 100% (3548/3548), done.
From https://github.com/sitaramc/gitolite
 * [new branch]      bp-v2.0.3  -> origin/bp-v2.0.3
 * [new branch]      fedora-temp -> origin/fedora-temp
 * [new branch]      gh-pages   -> origin/gh-pages
 * [new branch]      master     -> origin/master
 * [new branch]      pu         -> origin/pu
 * [new branch]      temp-br--data-dumper-problem-demo -> origin/temp-br--data-dumper-problem-demo
 * [new branch]      vrs        -> origin/vrs
 * [new tag]         v2.1       -> v2.1
From https://github.com/sitaramc/gitolite
 * [new tag]         v0.50      -> v0.50
 * [new tag]         v0.55      -> v0.55
[...]
 * [new tag]         v2.0rc2    -> v2.0rc2
 * [new tag]         v2.1       -> v2.1
                                   ^^^^
                                    |
                                    --- could be the tag you need

As mentioned above, the only traces are the pack files, so at least you can easily clean them once you have your information:

VonC@NETVONC /c/prog/git/g2 (master)
$ l .git/objects/pack/
total 1000
drwxr-xr-x    4 VonC     Administ        0 Nov  8 19:45 ..
-r--r--r--    1 VonC     Administ  1898987 Nov  8 19:46 pack-c70771bc8a5ecc099ed88da0c3f631f84b34fe9d.pack
-r--r--r--    1 VonC     Administ   144264 Nov  8 19:46 pack-c70771bc8a5ecc099ed88da0c3f631f84b34fe9d.idx
drwxr-xr-x    2 VonC     Administ     4096 Nov  8 19:46 .

Answer 2

#!/usr/bin/awk -f
BEGIN {
  FS = "[ /^]+"
  while ("git ls-remote " ARGV[1] "| sort -Vk2" | getline) {
    if (!sha)
      sha = substr($0, 1, 7)
    tag = $3
  }
  while ("curl -s " ARGV[1] "/releases/tag/" tag | getline)
    if ($3 ~ "commits")
      com = $2
  printf com ? "%s-%s-g%s\n" : "%s\n", tag, com, sha
}

Sample output

$ git-describe-remote.awk https://github.com/stedolan/jq
jq-1.4-148-g89791a0