NAME

       gitnamespaces - Git namespaces

SYNOPSIS

       GIT_NAMESPACE=<namespace> git upload-pack
       GIT_NAMESPACE=<namespace> git receive-pack

DESCRIPTION

       Git supports dividing the refs of a single repository into multiple namespaces, each of
       which has its own branches, tags, and HEAD. Git can expose each namespace as an
       independent repository to pull from and push to, while sharing the object store, and
       exposing all the refs to operations such as git-gc(1).

       Storing multiple repositories as namespaces of a single repository avoids storing
       duplicate copies of the same objects, such as when storing multiple branches of the same
       source. The alternates mechanism provides similar support for avoiding duplicates, but
       alternates do not prevent duplication between new objects added to the repositories
       without ongoing maintenance, while namespaces do.

       To specify a namespace, set the GIT_NAMESPACE environment variable to the namespace. For
       each ref namespace, Git stores the corresponding refs in a directory under
       refs/namespaces/. For example, GIT_NAMESPACE=foo will store refs under
       refs/namespaces/foo/. You can also specify namespaces via the --namespace option to
       git(1).

       Note that namespaces which include a / will expand to a hierarchy of namespaces; for
       example, GIT_NAMESPACE=foo/bar will store refs under
       refs/namespaces/foo/refs/namespaces/bar/. This makes paths in GIT_NAMESPACE behave
       hierarchically, so that cloning with GIT_NAMESPACE=foo/bar produces the same result as
       cloning with GIT_NAMESPACE=foo and cloning from that repo with GIT_NAMESPACE=bar. It also
       avoids ambiguity with strange namespace paths such as foo/refs/heads/, which could
       otherwise generate directory/file conflicts within the refs directory.

       git-upload-pack(1) and git-receive-pack(1) rewrite the names of refs as specified by
       GIT_NAMESPACE. git-upload-pack and git-receive-pack will ignore all references outside the
       specified namespace.

       The smart HTTP server, git-http-backend(1), will pass GIT_NAMESPACE through to the backend
       programs; see git-http-backend(1) for sample configuration to expose repository namespaces
       as repositories.

       For a simple local test, you can use git-remote-ext(1):

           git clone ext::'git --namespace=foo %s /tmp/prefixed.git'

SECURITY

       Anyone with access to any namespace within a repository can potentially access objects
       from any other namespace stored in the same repository. You can’t directly say "give me
       object ABCD" if you don’t have a ref to it, but you can do some other sneaky things like:

        1. Claiming to push ABCD, at which point the server will optimize out the need for you to
           actually send it. Now you have a ref to ABCD and can fetch it (claiming not to have
           it, of course).

        2. Requesting other refs, claiming that you have ABCD, at which point the server may
           generate deltas against ABCD.

       None of this causes a problem if you only host public repositories, or if everyone who may
       read one namespace may also read everything in every other namespace (for instance, if
       everyone in an organization has read permission to every repository).