A simple example of a puppet config with git automatic deployment based on "release-#" tags

git.pp

class git {
    package { 'git':
        ensure => installed,
    }

    define repository($project = $name, $cwd, $dir = "$cwd/${project}",
                      $repo = "githost:${project}.git", $no_ensure = 0) {
        $require = $no_ensure ? {
            1       => [Package['git']],
            default => [Package['git'], File[$cwd]],
        }

        include git

        exec { "git-clone-${name}":
            require => $require,
            command => "git clone ${repo} ${dir}",
            cwd     => $cwd,
            user    => root,
            creates => $dir,
        }
    }

    define web_project($project = $name, $basedir = "/var/www", $dir = undef) {
        $mydir = "$dir" ? {
            /./     => $dir,
            default => "${basedir}/${project}",
        }

        git::repository { $project: }

        exec { "git-web-reset-${name}":
            logoutput => on_failure,
            require   => Git::Repository[$project],
            command   => "git reset --hard HEAD",
            cwd       => $mydir,
            user      => root,
        }

        exec { "git-web-clean-${name}":
            logoutput => on_failure,
            require   => Exec["git-web-reset-${name}"],
            command   => "git clean -f",
            cwd       => $mydir,
            user      => root,
        }

        exec { "git-web-fetch-${name}":
            logoutput => on_failure,
            require   => Exec["git-web-clean-${name}"],
            command   => "git fetch origin",
            cwd       => $mydir,
            user      => root,
        }

        exec { "git-web-tag-${name}":
            logoutput => on_failure,
            require   => Exec["git-web-fetch-${name}"],
            command   => "git checkout \"release-\$(git tag | cut -d\\- -f2 | sort -rn | head -n1)\"",
            cwd       => $mydir,
            user      => root,
        }

        file { "git-web-conf-${name}":
            owner   => root,
            group   => root,
            mode    => 0644,
            require => Exec["git-web-tag-${name}"],
            ensure  => link,
            path    => "/etc/httpd/conf.d/${project}.conf",
            target  => "$mydir/conf/${project}.conf",
        }
    }
}

site.pp

node webserver {
    # various setup for web server

    $git_web_projects = ['blog', 'analytics', 'main_site']
    git::web_project { $git_web_projects: }
}