Flush out the update guide from 8.17 - 9.0

And bump the stable branch version in the installation from source guide

doc/install/installation.md

@@ -288,9 +288,9 @@ sudo usermod -aG redis git
 ### Clone the Source
 
     # Clone GitLab repository
-    sudo -u git -H git clone https://gitlab.com/gitlab-org/gitlab-ce.git -b 8-17-stable gitlab
+    sudo -u git -H git clone https://gitlab.com/gitlab-org/gitlab-ce.git -b 9-0-stable gitlab
 
-**Note:** You can change `8-17-stable` to `master` if you want the *bleeding edge* version, but never install master on a production server!
+**Note:** You can change `9-0-stable` to `master` if you want the *bleeding edge* version, but never install master on a production server!
 
 ### Configure It
 

doc/update/8.17-to-9.0.md

@@ -1,3 +1,163 @@
+# From 8.17 to 9.0
+
+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
+
+```bash
+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
+
+We will continue supporting Ruby < 2.3 for the time being but we recommend you
+upgrade to Ruby 2.3 if you're running a source installation, as this is the same
+version that ships with our Omnibus package.
+
+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-2.3.3.tar.gz
+echo '1014ee699071aa2ddd501907d18cbe15399c997d ruby-2.3.3.tar.gz' | shasum -c - && tar xzf ruby-2.3.3.tar.gz
+cd ruby-2.3.3
+./configure --disable-install-rdoc
+make
+sudo make install
+```
+
+Install Bundler:
+
+```bash
+sudo gem install bundler --no-ri --no-rdoc
+```
+
+### 4. Update Node
+
+GitLab now runs [webpack](http://webpack.js.org) to compile frontend assets and
+it has a minimum requirement of node v4.3.0.
+
+You can check which version you are running with `node -v`. If you are running
+a version older than `v4.3.0` you will need to update to a newer version.  You
+can find instructions to install from community maintained packages or compile
+from source at the nodejs.org website.
+
+<https://nodejs.org/en/download/>
+
+
+Since GitLab 8.17, GitLab requires the use of yarn yarn >= v0.17.0  to manage
+javascript dependencies.
+
+    # install yarn
+    curl --location https://yarnpkg.com/install.sh | bash -
+
+More information can be found on the yarnpkg.com website.
+
+<https://yarnpkg.com/en/docs/install>
+
+### 5. Get latest code
+
+```bash
+cd /home/git/gitlab
+
+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
+cd /home/git/gitlab
+
+sudo -u git -H git checkout 9-0-stable
+```
+
+OR
+
+For GitLab Enterprise Edition:
+
+```bash
+cd /home/git/gitlab
+
+sudo -u git -H git checkout 9-0-stable-ee
+```
+
+### 6. 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
+
+# Install/update frontend asset dependencies
+sudo -u git -H npm install --production
+
+# Clean up assets and cache
+sudo -u git -H bundle exec rake gitlab:assets:clean gitlab:assets:compile cache:clear RAILS_ENV=production
+```
+
+**MySQL installations**: Run through the `MySQL strings limits` and `Tables and data conversion to utf8mb4` [tasks](../install/database_mysql.md).
+
+### 7. 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
+
+sudo -u git -H bundle exec rake "gitlab:workhorse:install[/home/git/gitlab-workhorse]" RAILS_ENV=production
+```
+
+### 8. Update gitlab-shell
+
+```bash
+cd /home/git/gitlab-shell
+
+sudo -u git -H git fetch --all --tags
+sudo -u git -H git checkout v5.0.0
+```
+
+### 9. Update configuration files
+
+#### New configuration options for `gitlab.yml`
+
+There are new configuration options available for [`gitlab.yml`][yaml]. View them with the command below and apply them manually to your current `gitlab.yml`:
+
+```sh
+cd /home/git/gitlab
+
+git diff origin/8-17-stable:config/gitlab.yml.example origin/9-0-stable:config/gitlab.yml.example
+```
+
 #### Configuration changes for repository storages
 
 This version introduces a new configuration structure for repository storages.
@@ -85,3 +245,78 @@ 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/9-0-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/8-17-stable/config/initializers/smtp_settings.rb.sample#L13
+
+#### Init script
+
+Ensure you're still up-to-date with the latest init script changes:
+
+```bash
+cd /home/git/gitlab
+
+sudo cp lib/support/init.d/gitlab /etc/init.d/gitlab
+```
+
+For Ubuntu 16.04.1 LTS:
+
+```bash
+sudo systemctl daemon-reload
+```
+
+### 10. Start application
+
+```bash
+sudo service gitlab start
+sudo service nginx restart
+```
+
+### 11. Check application status
+
+Check if GitLab and its environment are configured correctly:
+
+```bash
+cd /home/git/gitlab
+
+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:
+
+```bash
+cd /home/git/gitlab
+
+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 (8.17)
+
+### 1. Revert the code to the previous version
+
+Follow the [upgrade guide from 8.16 to 8.17](8.16-to-8.17.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.
+
+[yaml]: https://gitlab.com/gitlab-org/gitlab-ce/blob/9-0-stable/config/gitlab.yml.example