######################################################################
    GitMeta 0.05
######################################################################

NAME
    GitMeta - Clone/update many Git repositories using Meta repos

SYNOPSIS
          # use the command line interface
        gitmeta-update gitmeta-repo-loc meta.gmf /local/git/repo/dir

DESCRIPTION
    GetMeta allows you to work on dozens of git repositories hosted on
    different servers, and update all of your local copies with a single
    command. It defines a new syntax, called GMF (git meta format), to
    configure many different remote git repository locations and provides a
    script, "gitmeta-update", to create local copies of all of these repos
    or updates them if they already exist. This is useful to

    *   periodically update your local clones while you have an Internet
        connection going so they're up-to-date later when you're offline.

    *   move to a new system and create clones of all of your favorite git
        repos with a single command.

  SIMPLE EXAMPLE
    For example, if you want to follow the Perl core developers on
    perl5.git.perl.org and also the Log4perl project on Github, simply put
    these lines into a new file "myrepos.gmf":

        # myrepos.gmf

        # Log4perl project
        - git://github.com/mschilli/log4perl.git

        # Perl core development
        - git://perl5.git.perl.org/perl.git

    Then, if you run

        gitmeta-update myrepos.gmf ~/my-git-repos

    the script will create clones of theses repos in the directory
    "~/my-git-repos" (it will ask to create it if it doesn't exist yet) or
    update them if they're already cloned but out-of-date:

        Updating git://perl5.git.perl.org/perl.git
        ...
        Updating git://github.com/mschilli/log4perl.git
        ...

    If you look your local "~/my-git-repos" directory, you now have clones
    of both projects, ready to use:

        $ ls ~/my-git-repos
        log4perl
        perl

  REMOTE GITMETA REPOS
    Having the meta configuration "myrepos.gmf" local on your box is nice
    for testing, but it's much more powerful to store it in a new repo
    somewhere on the Net, e.g. "github.com/mschilli/gitmeta-test" (this
    actually exists for your testing pleasure). Now, wherever you are,
    simply call

        gitmeta-update git://github.com/mschilli/gitmeta-test \
          myrepos.gmf ~/my-git-repos

    and the script will go out and fetch the git meta configuration from
    github, process each entry, and create or update the corresponding
    repositories in your local git repo directory ("~/my-git-repos").

  ADVANCED EXAMPLE
    If you want to follow all repositories of a given user (like yourself)
    on Github, or you want to clone all repositories in a given directory on
    your hosting service, it would be tiresome to constantly update your
    .gmf file when you create new repositories or remove retired ones.

    This is why GitMeta offers additional modules to automate this:

    "GitMeta::Github"
        Expands to all git repos of a given user on Github. Put

            # All github projects of user 'mschilli'
            -
                type: Github
                user: mschilli

        in your .gmf file (note the peculiar YAML syntax requiring
        indentation and an empty - line to define an array entry referencing
        a hash) then "gitmeta-update" will fetch a list of all Github
        projects of user "user" and add them to the processing list, before
        it starts cloning/updating those repos.

    "GitMeta::SshDir"
        Expands to all git repos in the given directory on a server via ssh.
        If you put

            # All projects in directory 'projects' 
            # on some host via git/SSH
            -
                type: SshDir
                host: username@hoster.com
                dir:  projects

        in your .gmf, then "gitmeta-update" will fetch a list of all
        repositories in the given directory on the given host and add them
        to the processing list. Requires ssh keys to be set up or you'll be
        prompted for your password.

    "GitMeta::GMF"
        You guessed it: You can refer to other .gmf files in other gitmeta
        repos, which "gitmeta-update" will dutifully follow. If you put

            -
                type: GMF
                repo: user@devhost.com:git/gitmeta
                gmf_path: privdev.gmf

        in your .gmf file, "gitmeta-update" will fetch the .gmf file
        "privdev.gmf" from user@devhost.com:git/gitmeta, process its
        directives and add the results to the processing list.

        This mechanism allows you to group repos into several meta repos and
        retrieve them separately or combined. For example, if you have your
        private repositories in "user@devhost.com:git/gitmeta/priv.gmf" and
        your public repos in "user@devhost.com:git/gitmeta/pub.gmf", you can
        write a .gmf file that fetches them all at once:

            # all.gmf
            -
                type: GMF
                repo: user@devhost.com:git/gitmeta
                gmf_path: priv.gmf
            -
                type: GMF
                repo: user@devhost.com:git/gitmeta
                gmf_path: pub.gmf

        If you put that file in user@devhost.com:git/gitmeta as well, all
        you need to do is run

            gitmeta-update user@devhost.com:git gitmeta/all.gmf ~/local-dir

        to get all repos created/updated.

    To combine all of the above, let's say that you're following several
    projects on Github.com, another set of git repositories located on a
    private hosting service, the perl core development on
    "perl5.git.perl.org", and another git meta definition in another gitmeta
    repo. You define the following .gmf file (in YAML format):

        # gitmeta.gmf

        # Perl core development
        - git://perl5.git.perl.org/perl.git
    
        # All github projects of user 'mschilli'
        -
            type: Github
            user: mschilli

        # All projects in directory 'projects' 
        # on some host via git/SSH
        -
            type: SshDir
            host: username@hoster.com
            dir:  projects

        # Private Project via git/SSH
        - username@private.server.com:git/private-project.git

        # Another .gmf file somewhere in another gitmeta repo
        -
            type: GMF
            repo: user@devhost.com:git/gitmeta
            gmf_path: privdev.gmf

    Note that in order to update a local repository, gitsync will fetch the
    remote changes, but won't merge them into the local clone. This is
    because there might be merge conflicts and when updating dozens of repos
    in one quick run, you don't want to be interrupted to resolve a
    conflicted merge.

    So, in git parlance, "gitsync" performs a "git fetch", not a "git pull".
    The updates will therefore be available in your locally defined remote
    branches, and if you want to merge them into the local branches, you
    need to run a "git merge" (you don't need an Internet connection for
    that, so you can do this later), e.g. use

        git merge origin/master

    to merge the changes in the 'master' branch of the 'origin' remote into
    the local branch you're currently on (presumably 'master' as well).

TROUBLESHOOTING
    Make sure that 'git' is in your PATH.

FIRST PUBLICATION
    This module was first published in the German edition of Linux Magazin
    in August 2010:

        http://www.linux-magazin.de/Heft-Abo/Ausgaben/2010/08/Ueberall-Projekte

    An English translation is available here:

        http://www.linux-magazine.com/w3/issue/118/050-055_perl.pdf

LEGALESE
    Copyright 2010-2011 by Mike Schilli, all rights reserved. This program
    is free software, you can redistribute it and/or modify it under the
    same terms as Perl itself.

AUTHOR
    2010, Mike Schilli <cpan@perlmeister.com>