Documentation / gitnamespaces.txton commit config: describe 'pathname' value type (dca83ab)
   1gitnamespaces(7)
   2================
   3
   4NAME
   5----
   6gitnamespaces - Git namespaces
   7
   8SYNOPSIS
   9--------
  10[verse]
  11GIT_NAMESPACE=<namespace> 'git upload-pack'
  12GIT_NAMESPACE=<namespace> 'git receive-pack'
  13
  14
  15DESCRIPTION
  16-----------
  17
  18Git supports dividing the refs of a single repository into multiple
  19namespaces, each of which has its own branches, tags, and HEAD.  Git can
  20expose each namespace as an independent repository to pull from and push
  21to, while sharing the object store, and exposing all the refs to
  22operations such as linkgit:git-gc[1].
  23
  24Storing multiple repositories as namespaces of a single repository
  25avoids storing duplicate copies of the same objects, such as when
  26storing multiple branches of the same source.  The alternates mechanism
  27provides similar support for avoiding duplicates, but alternates do not
  28prevent duplication between new objects added to the repositories
  29without ongoing maintenance, while namespaces do.
  30
  31To specify a namespace, set the `GIT_NAMESPACE` environment variable to
  32the namespace.  For each ref namespace, Git stores the corresponding
  33refs in a directory under `refs/namespaces/`.  For example,
  34`GIT_NAMESPACE=foo` will store refs under `refs/namespaces/foo/`.  You
  35can also specify namespaces via the `--namespace` option to
  36linkgit:git[1].
  37
  38Note that namespaces which include a `/` will expand to a hierarchy of
  39namespaces; for example, `GIT_NAMESPACE=foo/bar` will store refs under
  40`refs/namespaces/foo/refs/namespaces/bar/`.  This makes paths in
  41`GIT_NAMESPACE` behave hierarchically, so that cloning with
  42`GIT_NAMESPACE=foo/bar` produces the same result as cloning with
  43`GIT_NAMESPACE=foo` and cloning from that repo with `GIT_NAMESPACE=bar`.  It
  44also avoids ambiguity with strange namespace paths such as `foo/refs/heads/`,
  45which could otherwise generate directory/file conflicts within the `refs`
  46directory.
  47
  48linkgit:git-upload-pack[1] and linkgit:git-receive-pack[1] rewrite the
  49names of refs as specified by `GIT_NAMESPACE`.  git-upload-pack and
  50git-receive-pack will ignore all references outside the specified
  51namespace.
  52
  53The smart HTTP server, linkgit:git-http-backend[1], will pass
  54GIT_NAMESPACE through to the backend programs; see
  55linkgit:git-http-backend[1] for sample configuration to expose
  56repository namespaces as repositories.
  57
  58For a simple local test, you can use linkgit:git-remote-ext[1]:
  59
  60----------
  61git clone ext::'git --namespace=foo %s /tmp/prefixed.git'
  62----------
  63
  64SECURITY
  65--------
  66
  67Anyone with access to any namespace within a repository can potentially
  68access objects from any other namespace stored in the same repository.
  69You can't directly say "give me object ABCD" if you don't have a ref to
  70it, but you can do some other sneaky things like:
  71
  72. Claiming to push ABCD, at which point the server will optimize out the
  73  need for you to actually send it. Now you have a ref to ABCD and can
  74  fetch it (claiming not to have it, of course).
  75
  76. Requesting other refs, claiming that you have ABCD, at which point the
  77  server may generate deltas against ABCD.
  78
  79None of this causes a problem if you only host public repositories, or
  80if everyone who may read one namespace may also read everything in every
  81other namespace (for instance, if everyone in an organization has read
  82permission to every repository).