repo Manifest Format
====================

A repo manifest describes the structure of a repo client; that is
the directories that are visible and where they should be obtained
from with git.

The basic structure of a manifest is a bare Git repository holding
a single 'default.xml' XML file in the top level directory.

Manifests are inherently version controlled, since they are kept
within a Git repository.  Updates to manifests are automatically
obtained by clients during `repo sync`.


XML File Format
---------------

A manifest XML file (e.g. 'default.xml') roughly conforms to the
following DTD:

  <!DOCTYPE manifest [
    <!ELEMENT manifest (remote*,
                        default?,
                        remove-project*,
                        project*,
                        add-remote*)>
  
    <!ELEMENT remote (EMPTY)>
    <!ATTLIST remote name         ID    #REQUIRED>
    <!ATTLIST remote fetch        CDATA #REQUIRED>
    <!ATTLIST remote review       CDATA #IMPLIED>
    <!ATTLIST remote project-name CDATA #IMPLIED>
  
    <!ELEMENT default (EMPTY)>
    <!ATTLIST default remote   IDREF #IMPLIED>
    <!ATTLIST default revision CDATA #IMPLIED>
  
    <!ELEMENT project (remote*)>
    <!ATTLIST project name     CDATA #REQUIRED>
    <!ATTLIST project path     CDATA #IMPLIED>
    <!ATTLIST project remote   IDREF #IMPLIED>
    <!ATTLIST project revision CDATA #IMPLIED>
  
    <!ELEMENT add-remote (EMPTY)>
    <!ATTLIST add-remote to-project   ID    #REQUIRED>
    <!ATTLIST add-remote name         ID    #REQUIRED>
    <!ATTLIST add-remote fetch        CDATA #REQUIRED>
    <!ATTLIST add-remote review       CDATA #IMPLIED>
    <!ATTLIST add-remote project-name CDATA #IMPLIED>
  
    <!ELEMENT remove-project (EMPTY)>
    <!ATTLIST remove-project name  CDATA #REQUIRED>
  ]>

A description of the elements and their attributes follows.


Element manifest
----------------

The root element of the file.


Element remote
--------------

One or more remote elements may be specified.  Each remote element
specifies a Git URL shared by one or more projects and (optionally)
the Gerrit review server those projects upload changes through.

Attribute `name`: A short name unique to this manifest file.  The
name specified here is used as the remote name in each project's
.git/config, and is therefore automatically available to commands
like `git fetch`, `git remote`, `git pull` and `git push`.

Attribute `fetch`: The Git URL prefix for all projects which use
this remote.  Each project's name is appended to this prefix to
form the actual URL used to clone the project.

Attribute `review`: Hostname of the Gerrit server where reviews
are uploaded to by `repo upload`.  This attribute is optional;
if not specified then `repo upload` will not function.

Attribute `project-name`: Specifies the name of this project used
by the review server given in the review attribute of this element.
Only permitted when the remote element is nested inside of a project
element (see below).  If not given, defaults to the name supplied
in the project's name attribute.

Element add-remote
------------------

Adds a remote to an existing project, whose name is given by the
to-project attribute.  This is functionally equivalent to nesting
a remote element under the project, but has the advantage that it
can be specified in the uesr's `local_manifest.xml` to add a remote
to a project declared by the normal manifest.

The element can be used to add a fork of an existing project that
the user needs to work with.


Element default
---------------

At most one default element may be specified.  Its remote and
revision attributes are used when a project element does not
specify its own remote or revision attribute.

Attribute `remote`: Name of a previously defined remote element.
Project elements lacking a remote attribute of their own will use
this remote.

Attribute `revision`: Name of a Git branch (e.g. `master` or
`refs/heads/master`).  Project elements lacking their own
revision attribute will use this revision.


Element project
---------------

One or more project elements may be specified.  Each element
describes a single Git repository to be cloned into the repo
client workspace.

Attribute `name`: A unique name for this project.  The project's
name is appended onto its remote's fetch URL to generate the actual
URL to configure the Git remote with.  The URL gets formed as:

  ${remote_fetch}/${project_name}.git

where ${remote_fetch} is the remote's fetch attribute and
${project_name} is the project's name attribute.  The suffix ".git"
is always appended as repo assumes the upstream is a forrest of
bare Git repositories.

The project name must match the name Gerrit knows, if Gerrit is
being used for code reviews.

Attribute `path`: An optional path relative to the top directory
of the repo client where the Git working directory for this project
should be placed.  If not supplied the project name is used.

Attribute `remote`: Name of a previously defined remote element.
If not supplied the remote given by the default element is used.

Attribute `revision`: Name of the Git branch the manifest wants
to track for this project.  Names can be relative to refs/heads
(e.g. just "master") or absolute (e.g. "refs/heads/master").
Tags and/or explicit SHA-1s should work in theory, but have not
been extensively tested.  If not supplied the revision given by
the default element is used.

Child element `remote`: Described like the top-level remote element,
but adds an additional remote to only this project.  These additional
remotes are fetched from first on the initial `repo sync`, causing
the majority of the project's object database to be obtained through
these additional remotes.


Element remove-project
----------------------

Deletes the named project from the internal manifest table, possibly
allowing a subsequent project element in the same manifest file to
replace the project with a different source.

This element is mostly useful in the local_manifest.xml, where
the user can remove a project, and possibly replace it with their
own definition.


Local Manifest
==============

Additional remotes and projects may be added through a local
manifest, stored in `$TOP_DIR/.repo/local_manifest.xml`.

For example:

  $ cat .repo/local_manifest.xml
  <?xml version="1.0" encoding="UTF-8"?>
  <manifest>
    <project path="manifest"
             name="tools/manifest" />
    <project path="platform-manifest"
             name="platform/manifest" />
  </manifest>

Users may add projects to the local manifest prior to a `repo sync`
invocation, instructing repo to automatically download and manage
these extra projects.

Currently the only supported feature of a local manifest is to
add new remotes and/or projects.  In the future a local manifest
may support picking different revisions of a project, or deleting
projects specified in the default manifest.