kotovalexarian-likes-gitlab/gitlab-org--gitlab-foss

Marcel Amirault e2fe9c8ee5 Docs: Merge EE doc/administration/geo to CE

2019-05-05 16:08:21 +00:00

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Disaster Recovery [PREMIUM ONLY]

Geo replicates your database, your Git repositories, and few other assets. We will support and replicate more data in the future, that will enable you to failover with minimal effort, in a disaster situation.

See Geo current limitations for more information.

CAUTION: Warning: Disaster recovery for multi-secondary configurations is in Alpha. For the latest updates, check the multi-secondary Disaster Recovery epic.

Promoting a secondary Geo node in single-secondary configurations

We don't currently provide an automated way to promote a Geo replica and do a failover, but you can do it manually if you have root access to the machine.

This process promotes a secondary Geo node to a primary node. To regain geographic redundancy as quickly as possible, you should add a new secondary node immediately after following these instructions.

Step 1. Allow replication to finish if possible

If the secondary node is still replicating data from the primary node, follow the planned failover docs as closely as possible in order to avoid unnecessary data loss.

Step 2. Permanently disable the primary node

CAUTION: Warning: If the primary node goes offline, there may be data saved on the primary node that has not been replicated to the secondary node. This data should be treated as lost if you proceed.

If an outage on the primary node happens, you should do everything possible to avoid a split-brain situation where writes can occur in two different GitLab instances, complicating recovery efforts. So to prepare for the failover, we must disable the primary node.

SSH into the primary node to stop and disable GitLab, if possible:
```
sudo gitlab-ctl stop
```
Prevent GitLab from starting up again if the server unexpectedly reboots:
```
sudo systemctl disable gitlab-runsvdir
```
CentOS only: In CentOS 6 or older, there is no easy way to prevent GitLab from being started if the machine reboots isn't available (see gitlab-org/omnibus-gitlab#3058). It may be safest to uninstall the GitLab package completely:
```
yum remove gitlab-ee
```
Ubuntu 14.04 LTS: If you are using an older version of Ubuntu or any other distro based on the Upstart init system, you can prevent GitLab from starting if the machine reboots by doing the following:
```
initctl stop gitlab-runsvvdir
echo 'manual' > /etc/init/gitlab-runsvdir.override
initctl reload-configuration
```
If you do not have SSH access to the primary node, take the machine offline and prevent it from rebooting by any means at your disposal. Since there are many ways you may prefer to accomplish this, we will avoid a single recommendation. You may need to:
- Reconfigure the load balancers.
- Change DNS records (e.g., point the primary DNS record to the secondary node in order to stop usage of the primary node).
- Stop the virtual servers.
- Block traffic through a firewall.
- Revoke object storage permissions from the primary node.
- Physically disconnect a machine.
If you plan to update the primary domain DNS record, you may wish to lower the TTL now to speed up propagation.

Step 3. Promoting a secondary node

NOTE: Note: A new secondary should not be added at this time. If you want to add a new secondary, do this after you have completed the entire process of promoting the secondary to the primary.

Promoting a secondary node running on a single machine

SSH in to your secondary node and login as root:
```
sudo -i
```

Edit /etc/gitlab/gitlab.rb to reflect its new status as primary by removing any lines that enabled the geo_secondary_role:

## In pre-11.5 documentation, the role was enabled as follows. Remove this line.
geo_secondary_role['enable'] = true

## In 11.5+ documentation, the role was enabled as follows. Remove this line.
roles ['geo_secondary_role']

Promote the secondary node to the primary node. Execute:
```
gitlab-ctl promote-to-primary-node
```
Verify you can connect to the newly promoted primary node using the URL used previously for the secondary node.
If successful, the secondary node has now been promoted to the primary node.

Promoting a secondary node with HA

The gitlab-ctl promote-to-primary-node command cannot be used yet in conjunction with High Availability or with multiple machines, as it can only perform changes on a secondary with only a single machine. Instead, you must do this manually.

SSH in to the database node in the secondary and trigger PostgreSQL to promote to read-write:
```
sudo gitlab-pg-ctl promote
```

Edit /etc/gitlab/gitlab.rb on every machine in the secondary to reflect its new status as primary by removing any lines that enabled the geo_secondary_role:

## In pre-11.5 documentation, the role was enabled as follows. Remove this line.
geo_secondary_role['enable'] = true

## In 11.5+ documentation, the role was enabled as follows. Remove this line.
roles ['geo_secondary_role']

After making these changes Reconfigure GitLab each machine so the changes take effect.

Promote the secondary to primary. SSH into a single application server and execute:
```
sudo gitlab-rake geo:set_secondary_as_primary
```
Verify you can connect to the newly promoted primary using the URL used previously for the secondary.
Success! The secondary has now been promoted to primary.

Step 4. (Optional) Updating the primary domain DNS record

Updating the DNS records for the primary domain to point to the secondary node will prevent the need to update all references to the primary domain to the secondary domain, like changing Git remotes and API URLs.

SSH into the secondary node and login as root:
```
sudo -i
```
Update the primary domain's DNS record. After updating the primary domain's DNS records to point to the secondary node, edit /etc/gitlab/gitlab.rb on the secondary node to reflect the new URL:
```
# Change the existing external_url configuration
external_url 'https://<new_external_url>'
```
NOTE: Note Changing external_url won't prevent access via the old secondary URL, as long as the secondary DNS records are still intact.
Reconfigure the secondary node for the change to take effect:
```
gitlab-ctl reconfigure
```
Execute the command below to update the newly promoted primary node URL:
```
gitlab-rake geo:update_primary_node_url
```
This command will use the changed external_url configuration defined in /etc/gitlab/gitlab.rb.
Verify you can connect to the newly promoted primary using its URL. If you updated the DNS records for the primary domain, these changes may not have yet propagated depending on the previous DNS records TTL.

Step 5. (Optional) Add secondary Geo node to a promoted primary node

Promoting a secondary node to primary node using the process above does not enable Geo on the new primary node.

To bring a new secondary node online, follow the Geo setup instructions.

Step 6. (Optional) Removing the secondary's tracking database

Every secondary has a special tracking database that is used to save the status of the synchronization of all the items from the primary. Because the secondary is already promoted, that data in the tracking database is no longer required.

The data can be removed with the following command:

sudo rm -rf /var/opt/gitlab/geo-postgresql

Promoting secondary Geo replica in multi-secondary configurations

If you have more than one secondary node and you need to promote one of them, we suggest you follow Promoting a secondary Geo node in single-secondary configurations and after that you also need two extra steps.

Step 1. Prepare the new primary node to serve one or more secondary nodes

SSH into the new primary node and login as root:
```
sudo -i
```

Edit /etc/gitlab/gitlab.rb

## Enable a Geo Primary role (if you haven't yet)
roles ['geo_primary_role']

##
# Allow PostgreSQL client authentication from the primary and secondary IPs. These IPs may be
# public or VPC addresses in CIDR format, for example ['198.51.100.1/32', '198.51.100.2/32']
##
postgresql['md5_auth_cidr_addresses'] = ['<primary_node_ip>/32', '<secondary_node_ip>/32']

# Every secondary server needs to have its own slot so specify the number of secondary nodes you're going to have
postgresql['max_replication_slots'] = 1

##
## Disable automatic database migrations temporarily
## (until PostgreSQL is restarted and listening on the private address).
##
gitlab_rails['auto_migrate'] = false

(For more details about these settings you can read Configure the primary server)

Save the file and reconfigure GitLab for the database listen changes and the replication slot changes to be applied.
```
gitlab-ctl reconfigure
```
Restart PostgreSQL for its changes to take effect:
```
gitlab-ctl restart postgresql
```
Re-enable migrations now that PostgreSQL is restarted and listening on the private address.

Edit /etc/gitlab/gitlab.rb and change the configuration to true:
```
gitlab_rails['auto_migrate'] = true
```
Save the file and reconfigure GitLab:
```
gitlab-ctl reconfigure
```

Step 2. Initiate the replication process

Now we need to make each secondary node listen to changes on the new primary node. To do that you need to initiate the replication process again but this time for another primary node. All the old replication settings will be overwritten.

Troubleshooting

I followed the disaster recovery instructions and now two-factor auth is broken!

The setup instructions for Geo prior to 10.5 failed to replicate the otp_key_base secret, which is used to encrypt the two-factor authentication secrets stored in the database. If it differs between primary and secondary nodes, users with two-factor authentication enabled won't be able to log in after a failover.

If you still have access to the old primary node, you can follow the instructions in the Upgrading to GitLab 10.5 section to resolve the error. Otherwise, the secret is lost and you'll need to reset two-factor authentication for all users.

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