Add 9.5 update guide, with Gitaly specifics

doc/update/9.4-to-9.5.md

+# From 9.4 to 9.5
+
+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
+
+NOTE: GitLab 9.0 and higher only support Ruby 2.3.x and dropped support for Ruby 2.1.x. Be
+sure to upgrade your interpreter if necessary.
+
+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 8.17, GitLab requires the use of yarn `>= v0.17.0` to manage
+JavaScript dependencies.
+
+```bash
+curl --silent --show-error https://dl.yarnpkg.com/debian/pubkey.gpg | sudo apt-key add -
+echo "deb https://dl.yarnpkg.com/debian/ stable main" | sudo tee /etc/apt/sources.list.d/yarn.list
+sudo apt-get update
+sudo apt-get install yarn
+```
+
+More information can be found on the [yarn website](https://yarnpkg.com/en/docs/install).
+
+### 5. Update Go
+
+NOTE: GitLab 9.2 and higher only supports Go 1.8.3 and dropped support for Go
+1.5.x through 1.7.x. Be sure to upgrade your installation if necessary.
+
+You can check which version you are running with `go version`.
+
+Download and install Go:
+
+```bash
+# Remove former Go installation folder
+sudo rm -rf /usr/local/go
+
+curl --remote-name --progress https://storage.googleapis.com/golang/go1.8.3.linux-amd64.tar.gz
+echo '1862f4c3d3907e59b04a757cfda0ea7aa9ef39274af99a784f5be843c80c6772  go1.8.3.linux-amd64.tar.gz' | shasum -a256 -c - && \
+  sudo tar -C /usr/local -xzf go1.8.3.linux-amd64.tar.gz
+sudo ln -sf /usr/local/go/bin/{go,godoc,gofmt} /usr/local/bin/
+rm go1.8.3.linux-amd64.tar.gz
+```
+
+### 6. 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
+sudo -u git -H git checkout -- locale
+```
+
+For GitLab Community Edition:
+
+```bash
+cd /home/git/gitlab
+
+sudo -u git -H git checkout 9-5-stable
+```
+
+OR
+
+For GitLab Enterprise Edition:
+
+```bash
+cd /home/git/gitlab
+
+sudo -u git -H git checkout 9-5-stable-ee
+```
+
+### 7. Update gitlab-shell
+
+```bash
+cd /home/git/gitlab-shell
+
+sudo -u git -H git fetch --all --tags
+sudo -u git -H git checkout v$(</home/git/gitlab/GITLAB_SHELL_VERSION)
+sudo -u git -H bin/compile
+```
+
+### 8. Update gitlab-workhorse
+
+Install and compile gitlab-workhorse. GitLab-Workhorse uses
+[GNU Make](https://www.gnu.org/software/make/).
+If you are not using Linux you may have to run `gmake` instead of
+`make` below.
+
+```bash
+cd /home/git/gitlab-workhorse
+
+sudo -u git -H git fetch --all --tags
+sudo -u git -H git checkout v$(</home/git/gitlab/GITLAB_WORKHORSE_VERSION)
+sudo -u git -H make
+```
+
+### 9. Update Gitaly
+
+#### New Gitaly configuration options required
+
+In order to function Gitaly needs some additional configuration information. Below we assume you installed Gitaly in `/home/git/gitaly` and Gitlab-shell in `/home/git/gitlab-shell'.
+
+```shell
+echo '
+[gitaly-ruby]
+dir = "/home/git/gitaly/ruby"
+
+[gitlab-shell]
+dir = "/home/git/gitlab-shell"
+' | sudo -u git tee -a /home/git/gitaly/config.toml
+```
+
+#### Check Gitaly configuration
+
+Due to a bug in the `rake gitlab:gitaly:install` script your Gitaly
+configuration file may contain syntax errors. The block name
+`[[storages]]`, which may occur more than once in your `config.toml`
+file, should be `[[storage]]` instead.
+
+```shell
+sudo -u git -H sed -i.pre-9.5 's/\[\[storages\]\]/[[storage]]/' /home/git/gitaly/config.toml
+```
+
+#### Compile Gitaly
+
+```shell
+cd /home/git/gitaly
+sudo -u git -H git fetch --all --tags
+sudo -u git -H git checkout v$(</home/git/gitlab/GITALY_SERVER_VERSION)
+sudo -u git -H make
+```
+
+### 10. Update MySQL permissions
+
+If you are using MySQL you need to grant the GitLab user the necessary
+permissions on the database:
+
+```bash
+mysql -u root -p -e "GRANT TRIGGER ON \`gitlabhq_production\`.* TO 'git'@'localhost';"
+```
+
+If you use MySQL with replication, or just have MySQL configured with binary logging,
+you will need to also run the following on all of your MySQL servers:
+
+```bash
+mysql -u root -p -e "SET GLOBAL log_bin_trust_function_creators = 1;"
+```
+
+You can make this setting permanent by adding it to your `my.cnf`:
+
+```
+log_bin_trust_function_creators=1
+```
+
+### 11. Update configuration files
+
+#### New configuration options for `gitlab.yml`
+
+There might be 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/9-4-stable:config/gitlab.yml.example origin/9-5-stable:config/gitlab.yml.example
+```
+
+#### Nginx configuration
+
+Ensure you're still up-to-date with the latest NGINX configuration changes:
+
+```sh
+cd /home/git/gitlab
+
+# For HTTPS configurations
+git diff origin/9-4-stable:lib/support/nginx/gitlab-ssl origin/9-5-stable:lib/support/nginx/gitlab-ssl
+
+# For HTTP configurations
+git diff origin/9-4-stable:lib/support/nginx/gitlab origin/9-5-stable:lib/support/nginx/gitlab
+```
+
+If you are using Strict-Transport-Security in your installation to continue using it you must enable it in your Nginx
+configuration as GitLab application no longer handles setting it.
+
+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/9-5-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/9-4-stable/config/initializers/smtp_settings.rb.sample#L13
+
+#### Init script
+
+There might be new configuration options available for [`gitlab.default.example`][gl-example]. View them with the command below and apply them manually to your current `/etc/default/gitlab`:
+
+```sh
+cd /home/git/gitlab
+
+git diff origin/9-4-stable:lib/support/init.d/gitlab.default.example origin/9-5-stable:lib/support/init.d/gitlab.default.example
+```
+
+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
+```
+
+### 12. 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
+
+# Update node dependencies and recompile assets
+sudo -u git -H bundle exec rake yarn:install gitlab:assets:clean gitlab:assets:compile RAILS_ENV=production NODE_ENV=production
+
+# Clean up cache
+sudo -u git -H bundle exec rake 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).
+
+### 13. Start application
+
+```bash
+sudo service gitlab start
+sudo service nginx restart
+```
+
+### 14. 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 (9.4)
+
+### 1. Revert the code to the previous version
+
+Follow the [upgrade guide from 9.3 to 9.4](9.3-to-9.4.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/9-5-stable/config/gitlab.yml.example
+[gl-example]: https://gitlab.com/gitlab-org/gitlab-ce/blob/9-5-stable/lib/support/init.d/gitlab.default.example