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GITNAMESPACES(7) Git Manual GITNAMESPACES(7)
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).
Git 2.1.4 05/28/2018 GITNAMESPACES(7)
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