gitlab: Slapos'ify / tweak gitconfig and hook it into the system

Convert gitconfig template to jinja2 (reusing already-there
`email_display_name` and `email_from` parameters for commits generated by
gitlab).

System-level git config from gitlab-omnibus is also imported to this
file (on slapos we cannot tweak system-level git config -
software/.../parts/git/... is read-only for programs in instance
partitions - so we move all gitlab's system-wide git settings to this
"user-level" gitconfig.

System gitconfig in omnibus is defined here:

    https://gitlab.com/gitlab-org/omnibus-gitlab/blob/8eda093/files/gitlab-cookbooks/gitlab/attributes/default.rb#L23

so it is

    pack.threads = 1    and
    receive.fsckObjects = true

which makes sense to not waste a lot of memory when packing and not to
allow corrupt objects to enter to system by evil users intentionally.

To make the file foundable by git - we put it into partition root
directory and set $HOME to point to partition root when running
appropriate programs / services.

NOTE we'll need to upgrade gitlab-shell and gitlab-workhorse to
    propagate $HOME for this setting to actually have effect.
    See the next patch.

/cc @kazuhiko, @jerome

software/gitlab/instance-gitlab.cfg.in

@@ -15,6 +15,8 @@ parts =
     gitlab-{{ prog }}
 {% endfor %}
 
+    gitconfig
+
     gitlab-work
     gitlab-shell-work
 
@@ -171,6 +173,12 @@ template= {{ database_yml_in }}
 context-extra =
     section pgsql                   service-postgresql
 
+[gitconfig]
+<= etc-template
+template= {{ gitconfig_in }}
+# NOTE put directly into $HOME/ - this way git will pick it up
+rendered= ${directory:home}/.${:_buildout_section_name_}
+
 [gitlab-shell-config.yml]
 <= etc-template
 template= {{ gitlab_shell_config_yml_in }}
@@ -222,8 +230,10 @@ context-extra =
 [gitlab-bin]
 recipe  = slapos.cookbook:wrapper
 wrapper-path = ${directory:bin}/${:_buildout_section_name_}
+# NOTE $HOME needed to pick gitconfig
 environment  =
     BUNDLE_GEMFILE = {{ gitlab_repository_location }}/Gemfile
+    HOME = ${directory:home}
     RAILS_ENV = production
 
 # NOTE sys.argv[1:] implicitly appended
@@ -466,8 +476,10 @@ command-line    = {{ gitlab_workhorse }}
 # NOTE environment for:
 #   - git to be available on path
 #   - ruby to be available on path  (gitlab-workhorse -> gitlab-shell -> hooks  on push)
+#   - gitconfig be found from ~/.gitconfig
 environment =
     PATH={{ git_location }}/bin:{{ ruby_location }}/bin:%(PATH)s
+    HOME=${directory:home}
 
 depend  =
     ${promise-gitlab-workhorse:recipe}

software/gitlab/instance.cfg.in

@@ -47,6 +47,7 @@ context =
 # config files
     raw config_ru_in                ${config.ru.in:target}
     raw database_yml_in             ${database.yml.in:target}
+    raw gitconfig_in                ${gitconfig.in:target}
     raw gitlab_parameters_cfg       ${gitlab-parameters.cfg:target}
     raw gitlab_shell_config_yml_in  ${gitlab-shell-config.yml.in:target}
     raw gitlab_unicorn_startup_in   ${gitlab-unicorn-startup.in:target}

software/gitlab/software.cfg

@@ -196,6 +196,10 @@ url     = ${:_profile_base_location_}/template/${:_buildout_section_name_}
 <= download-template
 # md5sum = TODO
 
+[gitconfig.in]
+<= download-template
+# md5sum = TODO
+
 [gitlab-parameters.cfg]
 <= download-file
 # md5sum = TODO

software/gitlab/template/gitconfig.erb

-# This file is managed by gitlab-ctl. Manual changes will be
-# erased! To change the contents below, edit /etc/gitlab/gitlab.rb
-# and run `sudo gitlab-ctl reconfigure`.
-
-[user]
-        name = <%= node['gitlab']['user']['git_user_name'] %>
-        email = <%= node['gitlab']['user']['git_user_email'] %>
-[core]
-        autocrlf = input

software/gitlab/template/gitconfig.in

+{{ autogenerated }}
+# global git configuration for GitLab
+# see:
+# https://gitlab.com/gitlab-org/omnibus-gitlab/blob/master/files/gitlab-cookbooks/gitlab/attributes/default.rb
+# https://gitlab.com/gitlab-org/omnibus-gitlab/blob/master/files/gitlab-cookbooks/gitlab/templates/default/gitconfig.erb
+# (last updated for omnibus-gitlab 8.2.3+ce.0-0-g8eda093)
+#
+{% from 'macrolib.cfg.in' import cfg  with context %}
+
+# don't waste memory when packing (each thread uses own work memory)
+# besides it packs better with 1 thread
+[pack]
+        threads = 1
+
+# don't allow corrupt/broken objects to go in
+[receive]
+        fsckObjects = true
+
+
+[user]
+        name = {{ cfg('email_display_name') }}
+        email = {{ cfg('email_from') }}
+[core]
+        autocrlf = input