Add more information about adding a new Geo node

doc/administration/gitlab-geo/configuration.md

@@ -11,9 +11,10 @@ complete the process.
 **Table of Contents**  *generated with [DocToc](https://github.com/thlorenz/doctoc)*
 
 - [Repositories data replication](#repositories-data-replication)
-- [Authorized keys regeneration](#authorized-keys-regeneration)
+- [Create SSH key pairs for Geo nodes](#create-ssh-key-pairs-for-geo-nodes)
 - [Primary Node GitLab setup](#primary-node-gitlab-setup)
 - [Secondary Node GitLab setup](#secondary-node-gitlab-setup)
+    - [Authorized keys regeneration](#authorized-keys-regeneration)
 
 <!-- END doctoc generated TOC please keep comment here to allow auto update -->
 
@@ -37,50 +38,74 @@ chmod ug+rwX,o-rwx /home/git/repositories
 where `1.2.3.4` is the IP of the primary node.
 
 If this step is not followed, the secondary node will eventually clone and
-fetch every missing repository as they are updated on the primary node, so
-syncing the repositories beforehand will buy you some time.
+fetch every missing repository as they are updated with new commits on the
+primary node, so syncing the repositories beforehand will buy you some time.
 
-## Authorized keys regeneration
+## Create SSH key pairs for Geo nodes
 
-The final step will be to regenerate the keys for `.ssh/authorized_keys` using
-the following command: (HTTPS clone will still work without this extra step):
+When adding a Geo node you must provide an SSH public key of the user that your
+GitLab instance runs on (unless changed, should be the user `git`). This user
+will act as a "normal user" who fetches from the primary Geo node.
 
-```
-# For Omnibus installations
-gitlab-rake gitlab:shell:setup
+Run the command below on each server that will be a Geo node (primary or
+secondary), and paste the contents of `id_rsa.pub` to the admin area
+(**Admin Area > Geo Nodes**) when adding a new node:
 
-# For source installations
-sudo -u git -H bundle exec rake gitlab:shell:setup RAILS_ENV=production
+```bash
+sudo -u git -H ssh-keygen
 ```
 
+The public key for Omnibus installations will be at `/var/opt/gitlab/.ssh/id_rsa.pub`,
+whereas for installation from source it will be at `/home/git/.ssh/id_rsa.pub`.
+
 ## Primary Node GitLab setup
 
 >**Note:**
 You will need to setup your database into a **Master <-> Slave** replication
 topology, and your Primary node should always point to a database's Master
-instance. If you haven't done that already, read [database replication](database.md).
+instance. If you haven't done that already, read [database replication](./database.md).
 
-To turn your GitLab instance into a primary Geo node, go to
-**Admin Area > Geo Nodes** (`/admin/geo_nodes`).
+Go to the server that you chose to be your primary, and visit
+**Admin Area > Geo Nodes** (`/admin/geo_nodes`) in order to add the Geo nodes.
+Although we are looking at the primary Geo node setup, this is where you also
+add any secondary servers as well.
 
-In this area you add all your nodes. The first node you add must be your
-primary and the others are the secondary ones.
-
-| Setting | Description |
-| ------- | ----------- |
-| Primary | This marks a Geo Node as primary. There can be only one primary, make sure that you first add the primary node and then all the others.
-| URL | Your instance's full URL, in the same way it is configured in `gitlab.yml` (source based installations) or `/etc/gitlab/gitlab.rb` (omnibus installations) |
-|Public Key | The SSH public key of the user that your GitLab instance runs on (unless changed, should be the user `git`). That means that you have to go in each Geo Node separately and create an SSH key pair.
+The very first node you add must be your primary, and the rest are the secondary
+ones. Make sure to check the box 'This is a primary node' when adding it.
 
 ![Geo Nodes Screen](img/geo-nodes-screen.png)
 
 ---
 
+In the following table you can see what all these settings mean.
+
+| Setting | Description |
+| ------- | ----------- |
+| Primary | This marks a Geo Node as primary. There can be only one primary, make sure that you first add the primary node and then all the others.
+| URL | Your instance's full URL, in the same way it is configured in `gitlab.yml` (source based installations) or `/etc/gitlab/gitlab.rb` (omnibus installations). |
+|Public Key | The SSH public key of the user that your GitLab instance runs on (unless changed, should be the user `git`). That means that you have to go in each Geo Node separately and create an SSH key pair. See the [SSH key creation](#create-ssh-key-pairs-for-geo-nodes) section.
+
 ## Secondary Node GitLab setup
 
 To install a secondary node, you must follow the normal GitLab Enterprise
 Edition installation, with some extra requirements:
 
-- You should point your database connection to a [replicated instance](database.md).
+- You should point your database connection to a [replicated instance](./database.md).
 - Your secondary node should be allowed to communicate via HTTP/HTTPS and
   SSH with your primary node (make sure your firewall is not blocking that).
+
+### Authorized keys regeneration
+
+The final step will be to regenerate the keys for `.ssh/authorized_keys` using
+the following command (HTTPS clone will still work without this extra step).
+
+On the secondary node where the database is [already replicated](./database.md),
+run the following:
+
+```
+# For Omnibus installations
+gitlab-rake gitlab:shell:setup
+
+# For source installations
+sudo -u git -H bundle exec rake gitlab:shell:setup RAILS_ENV=production
+```