Merge branch 'enable-repack-bitmaps' into 'master'

Create bitmaps during 'git gc'

## What does this MR do?

Add instructions to enable creation of Git packfile bitmaps.

## Why was this MR needed?

Because we still are not using Git packfile bitmaps in GitLab

[ci skip]

See merge request !6104

CHANGELOG

@@ -6,6 +6,7 @@ v 8.12.0 (unreleased)
   - Remove vendor prefixes for linear-gradient CSS (ClemMakesApps)
   - Add font color contrast to external label in admin area (ClemMakesApps)
   - Change logo animation to CSS (ClemMakesApps)
+  - Instructions for enabling Git packfile bitmaps !6104
   - Change merge_error column from string to text type
   - Reduce contributions calendar data payload (ClemMakesApps)
   - Add `web_url` field to issue, merge request, and snippet API objects (Ben Boeckel)

doc/install/installation.md

@@ -331,6 +331,9 @@ sudo usermod -aG redis git
     # Disable 'git gc --auto' because GitLab already runs 'git gc' when needed
     sudo -u git -H git config --global gc.auto 0
 
+    # Enable packfile bitmaps
+    sudo -u git -H git config --global repack.writeBitmaps true
+
     # Configure Redis connection settings
     sudo -u git -H cp config/resque.yml.example config/resque.yml
 

doc/update/8.11-to-8.12.md

+# From 8.11 to 8.12
+
+Make sure you view this update guide from the tag (version) of GitLab you would
+like to install. In most cases this should be the highest numbered production
+tag (without rc in it). You can select the tag in the version dropdown at the
+top left corner of GitLab (below the menu bar).
+
+If the highest number stable branch is unclear please check the
+[GitLab Blog](https://about.gitlab.com/blog/archives.html) for installation
+guide links by version.
+
+### 1. Stop server
+
+    sudo service gitlab stop
+
+### 2. Backup
+
+```bash
+cd /home/git/gitlab
+sudo -u git -H bundle exec rake gitlab:backup:create RAILS_ENV=production
+```
+
+### 3. Update Ruby
+
+If you are you running Ruby 2.1.x, you do not _need_ to upgrade Ruby yet, but you should note that support for 2.1.x is deprecated and we will require 2.3.x in 8.13. It's strongly recommended that you upgrade as soon as possible.
+
+You can check which version you are running with `ruby -v`.
+
+Download and compile Ruby:
+
+```bash
+mkdir /tmp/ruby && cd /tmp/ruby
+curl --remote-name --progress https://cache.ruby-lang.org/pub/ruby/2.3/ruby-2.3.1.tar.gz
+echo 'c39b4001f7acb4e334cb60a0f4df72d434bef711  ruby-2.3.1.tar.gz' | shasum --check - && tar xzf ruby-2.3.1.tar.gz
+cd ruby-2.3.1
+./configure --disable-install-rdoc
+make
+sudo make install
+```
+
+Install Bundler:
+
+```bash
+sudo gem install bundler --no-ri --no-rdoc
+```
+
+### 4. Get latest code
+
+```bash
+sudo -u git -H git fetch --all
+sudo -u git -H git checkout -- db/schema.rb # local changes will be restored automatically
+```
+
+For GitLab Community Edition:
+
+```bash
+sudo -u git -H git checkout 8-12-stable
+```
+
+OR
+
+For GitLab Enterprise Edition:
+
+```bash
+sudo -u git -H git checkout 8-12-stable-ee
+```
+
+### 5. Update gitlab-shell
+
+```bash
+cd /home/git/gitlab-shell
+sudo -u git -H git fetch --all --tags
+sudo -u git -H git checkout v3.4.0
+```
+
+### 6. Update gitlab-workhorse
+
+Install and compile gitlab-workhorse. This requires
+[Go 1.5](https://golang.org/dl) which should already be on your system from
+GitLab 8.1.
+
+```bash
+cd /home/git/gitlab-workhorse
+sudo -u git -H git fetch --all
+sudo -u git -H git checkout v0.7.8
+sudo -u git -H make
+```
+
+### 7. Install libs, migrations, etc.
+
+```bash
+cd /home/git/gitlab
+
+# MySQL installations (note: the line below states '--without postgres')
+sudo -u git -H bundle install --without postgres development test --deployment
+
+# PostgreSQL installations (note: the line below states '--without mysql')
+sudo -u git -H bundle install --without mysql development test --deployment
+
+# Optional: clean up old gems
+sudo -u git -H bundle clean
+
+# Run database migrations
+sudo -u git -H bundle exec rake db:migrate RAILS_ENV=production
+
+# Clean up assets and cache
+sudo -u git -H bundle exec rake assets:clean assets:precompile cache:clear RAILS_ENV=production
+```
+
+### 8. Update configuration files
+
+#### New configuration options for `gitlab.yml`
+
+There are new configuration options available for [`gitlab.yml`](config/gitlab.yml.example). View them with the command below and apply them manually to your current `gitlab.yml`:
+
+```sh
+git diff origin/8-11-stable:config/gitlab.yml.example origin/8-12-stable:config/gitlab.yml.example
+```
+
+#### Git configuration
+
+Configure Git to generate packfile bitmaps (introduced in Git 2.0) on
+the GitLab server during `git gc`.
+
+```sh
+sudo -u git -H git config --global repack.writeBitmaps true
+```
+
+#### Nginx configuration
+
+Ensure you're still up-to-date with the latest NGINX configuration changes:
+
+```sh
+# For HTTPS configurations
+git diff origin/8-11-stable:lib/support/nginx/gitlab-ssl origin/8-12-stable:lib/support/nginx/gitlab-ssl
+
+# For HTTP configurations
+git diff origin/8-11-stable:lib/support/nginx/gitlab origin/8-12-stable:lib/support/nginx/gitlab
+```
+
+If you are using Apache instead of NGINX please see the updated [Apache templates].
+Also note that because Apache does not support upstreams behind Unix sockets you
+will need to let gitlab-workhorse listen on a TCP port. You can do this
+via [/etc/default/gitlab].
+
+[Apache templates]: https://gitlab.com/gitlab-org/gitlab-recipes/tree/master/web-server/apache
+[/etc/default/gitlab]: https://gitlab.com/gitlab-org/gitlab-ce/blob/8-12-stable/lib/support/init.d/gitlab.default.example#L38
+
+#### SMTP configuration
+
+If you're installing from source and use SMTP to deliver mail, you will need to add the following line
+to config/initializers/smtp_settings.rb:
+
+```ruby
+ActionMailer::Base.delivery_method = :smtp
+```
+
+See [smtp_settings.rb.sample] as an example.
+
+[smtp_settings.rb.sample]:  https://gitlab.com/gitlab-org/gitlab-ce/blob/8-12-stable/config/initializers/smtp_settings.rb.sample#L13?
+
+#### Init script
+
+Ensure you're still up-to-date with the latest init script changes:
+
+    sudo cp lib/support/init.d/gitlab /etc/init.d/gitlab
+
+### 9. Start application
+
+    sudo service gitlab start
+    sudo service nginx restart
+
+### 10. Check application status
+
+Check if GitLab and its environment are configured correctly:
+
+    sudo -u git -H bundle exec rake gitlab:env:info RAILS_ENV=production
+
+To make sure you didn't miss anything run a more thorough check:
+
+    sudo -u git -H bundle exec rake gitlab:check RAILS_ENV=production
+
+If all items are green, then congratulations, the upgrade is complete!
+
+## Things went south? Revert to previous version (8.11)
+
+### 1. Revert the code to the previous version
+
+Follow the [upgrade guide from 8.10 to 8.11](8.10-to-8.11.md), except for the
+database migration (the backup is already migrated to the previous version).
+
+### 2. Restore from the backup
+
+```bash
+cd /home/git/gitlab
+sudo -u git -H bundle exec rake gitlab:backup:restore RAILS_ENV=production
+```
+
+If you have more than one backup `*.tar` file(s) please add `BACKUP=timestamp_of_backup` to the command above.