GitLab Geo

GitLab Geo provides the ability to have read-only, geographically distributed application deployments.

While external database services can be used, these documents focus on the use of the Omnibus GitLab for PostgreSQL to provide the most platform agnostic guide, and make use of the automation included in gitlab-ctl.

Requirements

To use GitLab Geo with the GitLab Helm chart, the following requirements must be met:

  • The use of external PostgreSQL services, as the PostgresSQL included with the chart is not exposed to outside networks, and doesn’t have WAL support required for replication.
  • The supplied database must:
    • Support replication.
    • The primary database must reachable by the primary application deployment, and all secondary database nodes (for replication).
    • Secondary databases only need to be reachable by the secondary application deployments.
    • Support SSL between primary and secondary.
  • The primary application instance must be reachable via HTTPS by all secondary instances. Secondary application instances must be accessible to the primary instance via HTTPS.

Overview

This guide uses 2 Omnibus GitLab instances, configuring only the PostgreSQL services needed, and 2 deployments of the GitLab Helm chart. It is intended to be the minimal required configuration. This documentation does not include SSL from application to database, support for other database providers, or promoting a secondary instance to primary.

The outline below should be followed in order:

  1. Setup Omnibus instances
  2. Setup Kubernetes clusters
  3. Collect information
  4. Configure Primary database
  5. Deploy chart as Geo Primary
  6. Set the Geo primary instance
  7. Configure Secondary database
  8. Copy secrets from primary cluster to secondary cluster
  9. Deploy chart as Geo Secondary
  10. Add Secondary Geo instance via Primary
  11. Confirm Operational Status

Set up Omnibus instances

For this process, two instances are required. One is the Primary, the other the Secondary. You may use any provider of machine infrastructure, on-premise or from a cloud provider.

Bear in mind that communication is required:

  • Between the two database instances for replication.
  • Between each database instance and their respective Kubernetes deployments:
    • The primary needs to expose TCP port 5432.
    • The secondary needs to expose TCP ports 5432 & 5431.

Install an operating system supported by Omnibus GitLab, and then install the Omnibus GitLab onto it. Do not provide the EXTERNAL_URL environment variable when installing, as we’ll provide a minimal configuration file before reconfiguring the package.

After you have installed the operating system, and the GitLab package, configuration can be created for the services that will be used. Before we do that, information must be collected.

Set up Kubernetes clusters

For this process, two Kubernetes clusters should be used. These can be from any provider, on-premise or from a cloud provider.

Bear in mind that communication is required:

  • To the respective database instances:
    • Primary outbound to TCP 5432.
    • Secondary outbound to TCP 5432 and 5431.
  • Between both Kubernetes Ingress via HTTPS.

Each cluster that is provisioned should have:

Collect information

To continue with the configuration, the following information needs to be collected from the various sources. Collect these, and make notes for use through the rest of this documentation.

  • Primary database:
    • IP address
    • hostname (optional)
  • Secondary database:
    • IP address
    • hostname (optional)
  • Primary cluster:
    • IP addresses of nodes
  • Secondary cluster:
    • IP addresses of nodes
  • Database Passwords (must pre-decide the passwords):
    • gitlab (used in postgresql['sql_user_password'], global.psql.password)
    • gitlab_geo (used in geo_postgresql['sql_user_password'], global.geo.psql.password)
    • gitlab_replicator (needed for replication)
  • Your GitLab license file

The gitlab and gitlab_geo database user passwords must exist in two forms: bare password, and PostgreSQL hashed password. To obtain the hashed form, perform the following commands on one of the Omnibus instances, which asks you to enter and confirm the password before outputting an appropriate hash value for you to make note of.

  1. gitlab-ctl pg-password-md5 gitlab
  2. gitlab-ctl pg-password-md5 gitlab_geo

Configure Primary database

This section is performed on the Primary Omnibus GitLab instance.

To configure the Primary database instance’s Omnibus GitLab, work from this example configuration:

### Geo Primary
external_url 'http://gitlab-primary.example.com'
roles ['geo_primary_role']
# The unique identifier for the Geo node.
gitlab_rails['geo_node_name'] = 'gitlab-primary.example.com'
gitlab_rails['auto_migrate'] = false
## turn off everything but the DB
sidekiq['enable']=false
puma['enable']=false
gitlab_workhorse['enable']=false
nginx['enable']=false
geo_logcursor['enable']=false
grafana['enable']=false
gitaly['enable']=false
redis['enable']=false
prometheus_monitoring['enable'] = false
## Configure the DB for network
postgresql['enable'] = true
postgresql['listen_address'] = '0.0.0.0'
postgresql['sql_user_password'] = 'gitlab_user_password_hash'
# !! CAUTION !!
# This list of CIDR addresses should be customized
# - primary application deployment
# - secondary database instance(s)
postgresql['md5_auth_cidr_addresses'] = ['0.0.0.0/0']

We must replace several items:

  • external_url must be updated to reflect the host name of our Primary instance.
  • gitlab_rails['geo_node_name'] must be replaced with a unique name for your node.
  • gitlab_user_password_hash must be replaced with the hashed form of the gitlab password.
  • postgresql['md5_auth_cidr_addresses'] can be update to be a list of explicit IP addresses, or address blocks in CIDR notation.

The md5_auth_cidr_addresses should be in the form of [ '127.0.0.1/24', '10.41.0.0/16']. It is important to include 127.0.0.1 in this list, as the automation in Omnibus GitLab connects using this. The addresses in this list should include the IP address (not hostname) of your Secondary database, and all nodes of your primary Kubernetes cluster. This can be left as ['0.0.0.0/0'], however it is not best practice.

After the configuration above is prepared:

  1. Place the content into /etc/gitlab/gitlab.rb
  2. Run gitlab-ctl reconfigure. If you experience any issues in regards to the service not listening on TCP, try directly restarting it with gitlab-ctl restart postgresql.
  3. Run gitlab-ctl set-replication-password to set the password for the gitlab_replicator user.
  4. Retrieve the Primary database server’s public certificate, this is needed for the Secondary database to be able to replicate (save this output):

    cat ~gitlab-psql/data/server.crt
    

Deploy chart as Geo Primary

This section is performed on the Primary Kubernetes cluster.

To deploy this chart as a Geo Primary, start from this example configuration:

  1. Create a secret containing the database password for the chart to consume. Replace PASSWORD below with the password for the gitlab database user:

    kubectl --namespace gitlab create secret generic geo --from-literal=postgresql-password=PASSWORD
    
  2. Create a primary.yaml file based on the example configuration and update the configuration to reflect the correct values:

    ### Geo Primary
    global:
      # See docs.gitlab.com/charts/charts/globals
      # Configure host & domain
      hosts:
        domain: example.com
      # configure DB connection
      psql:
        host: geo-1.db.example.com
        port: 5432
        password:
          secret: geo
          key: postgresql-password
      # configure geo (primary)
      geo:
        nodeName: primary.example.com
        enabled: true
        role: primary
    # External DB, disable
    postgresql:
      install: false
    
  3. Deploy the chart using this configuration:

    helm upgrade --install gitlab-geo gitlab/gitlab --namespace gitlab -f primary.yaml
    
    note
    This assumes you are using the gitlab namespace. If you want to use a different namespace, you should also replace it in --namespace gitlab throughout the rest of this document.
  4. Wait for the deployment to complete, and the application to come online. When the application is reachable, log in.

  5. Log in to GitLab, and upload your GitLab license file by navigating to /admin/license. This step is required for Geo to function.

Set the Geo Primary instance

Now that the chart has been deployed, and a license uploaded, we can configure this as the Primary instance. We will do this via the Toolbox Pod.

  1. Find the Toolbox Pod

    kubectl --namespace gitlab get pods -lapp=toolbox
    
  2. Run gitlab-rake geo:set_primary_node with kubectl exec:

    kubectl --namespace gitlab exec -ti gitlab-geo-toolbox-XXX -- gitlab-rake geo:set_primary_node
    
  3. Check the status of Geo configuration:

    kubectl --namespace gitlab exec -ti gitlab-geo-toolbox-XXX -- gitlab-rake gitlab:geo:check
    

    You should see output similar to below:

    WARNING: This version of GitLab depends on gitlab-shell 10.2.0, but you're running Unknown. Please update gitlab-shell.
    Checking Geo ...
    
    GitLab Geo is available ... yes
    GitLab Geo is enabled ... yes
    GitLab Geo secondary database is correctly configured ... not a secondary node
    Database replication enabled? ... not a secondary node
    Database replication working? ... not a secondary node
    GitLab Geo HTTP(S) connectivity ... not a secondary node
    HTTP/HTTPS repository cloning is enabled ... yes
    Machine clock is synchronized ... Exception: getaddrinfo: Servname not supported for ai_socktype
    Git user has default SSH configuration? ... yes
    OpenSSH configured to use AuthorizedKeysCommand ... no
      Reason:
      Cannot find OpenSSH configuration file at: /assets/sshd_config
      Try fixing it:
      If you are not using our official docker containers,
      make sure you have OpenSSH server installed and configured correctly on this system
      For more information see:
      doc/administration/operations/fast_ssh_key_lookup.md
    GitLab configured to disable writing to authorized_keys file ... yes
    GitLab configured to store new projects in hashed storage? ... yes
    All projects are in hashed storage? ... yes
    
    Checking Geo ... Finished
    
    • Don’t worry about Exception: getaddrinfo: Servname not supported for ai_socktype, as Kubernetes containers don’t have access to the host clock. This is OK.
    • OpenSSH configured to use AuthorizedKeysCommand ... no is expected. This Rake task is checking for a local SSH server, which is actually present in the gitlab-shell chart, deployed elsewhere, and already configured appropriately.

Configure Secondary database

This section is performed on the Secondary Omnibus GitLab instance.

To configure the Secondary database instance’s Omnibus GitLab, work from this example configuration:

### Geo Secondary
external_url 'http://gitlab-secondary.example.com'
roles ['geo_secondary_role']
gitlab_rails['enable'] = true
# The unique identifier for the Geo node.
gitlab_rails['geo_node_name'] = 'gitlab-secondary.example.com'
gitlab_rails['auto_migrate'] = false
geo_secondary['auto_migrate'] = false
## turn off everything but the DB
sidekiq['enable']=false
puma['enable']=false
gitlab_workhorse['enable']=false
nginx['enable']=false
geo_logcursor['enable']=false
grafana['enable']=false
gitaly['enable']=false
redis['enable']=false
prometheus_monitoring['enable'] = false
## Configure the DBs for network
postgresql['enable'] = true
postgresql['listen_address'] = '0.0.0.0'
postgresql['sql_user_password'] = 'gitlab_user_password_hash'
# !! CAUTION !!
# This list of CIDR addresses should be customized
# - secondary application deployment
# - secondary database instance(s)
postgresql['md5_auth_cidr_addresses'] = ['0.0.0.0/0']
geo_postgresql['listen_address'] = '0.0.0.0'
geo_postgresql['sql_user_password'] = 'gitlab_geo_user_password_hash'
# !! CAUTION !!
# This list of CIDR addresses should be customized
# - secondary application deployment
# - secondary database instance(s)
geo_postgresql['md5_auth_cidr_addresses'] = ['0.0.0.0/0']
gitlab_rails['db_password']='gitlab_user_password'

We must replace several items:

  • external_url must be updated to reflect the host name of our Secondary instance.
  • gitlab_rails['geo_node_name'] must be replaced with a unique name for your node.
  • gitlab_user_password_hash must be replaced with the hashed form of the gitlab password.
  • postgresql['md5_auth_cidr_addresses'] should be updated to be a list of explicit IP addresses, or address blocks in CIDR notation.
  • gitlab_geo_user_password_hash must be replaced with the hashed form of the gitlab_geo password.
  • geo_postgresql['md5_auth_cidr_addresses'] should be updated to be a list of explicit IP addresses, or address blocks in CIDR notation.
  • gitlab_user_password must be updated, and is used here to allow Omnibus GitLab to automate the PostgreSQL configuration.

The md5_auth_cidr_addresses should be in the form of [ '127.0.0.1/24', '10.41.0.0/16']. It is important to include 127.0.0.1 in this list, as the automation in Omnibus GitLab connects using this. The addresses in this list should include the IP addresses of all nodes of your Secondary Kubernetes cluster. This can be left as ['0.0.0.0/0'], however it is not best practice.

After configuration above is prepared:

  1. Check TCP connectivity to the primary node’s PostgreSQL server:

    openssl s_client -connect <primary_node_ip>:5432 </dev/null
    

    The output should show the following:

    CONNECTED(00000003)
    write:errno=0
    
    note
    If this step fails, you may be using the wrong IP address, or a firewall may be preventing access to the server. Check the IP address, paying close attention to the difference between public and private addresses and ensure that, if a firewall is present, the secondary node is permitted to connect to the primary node on port 5432.
  2. Place the content into /etc/gitlab/gitlab.rb
  3. Run gitlab-ctl reconfigure. If you experience any issues in regards to the service not listening on TCP, try directly restarting it with gitlab-ctl restart postgresql.
  4. Place the Primary database’s certificate content from above into primary.crt
  5. Set up PostgreSQL TLS verification on the secondary node:

    Install the primary.crt file:

    install \
       -D \
       -o gitlab-psql \
       -g gitlab-psql \
       -m 0400 \
       -T primary.crt ~gitlab-psql/.postgresql/root.crt
    

    PostgreSQL will now only recognize that exact certificate when verifying TLS connections. The certificate can only be replicated by someone with access to the private key, which is only present on the primary node.

  6. Test that the gitlab-psql user can connect to the primary node’s database (the default Omnibus database name is gitlabhq_production):

    sudo \
       -u gitlab-psql /opt/gitlab/embedded/bin/psql \
       --list \
       -U gitlab_replicator \
       -d "dbname=gitlabhq_production sslmode=verify-ca" \
       -W \
       -h <primary_node_ip>
    

    When prompted enter the password collected earlier for the gitlab_replicator user. If all worked correctly, you should see the list of primary node’s databases.

    A failure to connect here indicates that the TLS configuration is incorrect. Ensure that the contents of ~gitlab-psql/data/server.crt on the primary node match the contents of ~gitlab-psql/.postgresql/root.crt on the secondary node.

  7. Replicate the databases. Replace PRIMARY_DATABASE_HOST with the IP or hostname of your Primary database instance:

    gitlab-ctl replicate-geo-database --slot-name=geo_2 --host=PRIMARY_DATABASE_HOST
    
  8. After replication has finished, we must reconfigure the Omnibus GitLab one last time to ensure pg_hba.conf is correct for the secondary:

    gitlab-ctl reconfigure
    

Copy secrets from the primary cluster to the secondary cluster

Now copy a few secrets from the Primary Kubernetes deployment to the Secondary Kubernetes deployment:

  • gitlab-geo-gitlab-shell-host-keys
  • gitlab-geo-rails-secret
  • gitlab-geo-registry-secret, if Registry replication is enabled.
  1. Change your kubectl context to that of your Primary.
  2. Collect these secrets from the Primary deployment:

    kubectl get --namespace gitlab -o yaml secret gitlab-geo-gitlab-shell-host-keys > ssh-host-keys.yaml
    kubectl get --namespace gitlab -o yaml secret gitlab-geo-rails-secret > rails-secrets.yaml
    kubectl get --namespace gitlab -o yaml secret gitlab-geo-registry-secret > registry-secrets.yaml
    
  3. Change your kubectl context to that of your Secondary.
  4. Apply these secrets:

    kubectl --namespace gitlab apply -f ssh-host-keys.yaml
    kubectl --namespace gitlab apply -f rails-secrets.yaml
    kubectl --namespace gitlab apply -f registry-secrets.yaml
    

Next create a secret containing the database passwords. Replace the passwords below with the appropriate values:

kubectl --namespace gitlab create secret generic geo \
   --from-literal=postgresql-password=gitlab_user_password \
   --from-literal=geo-postgresql-password=gitlab_geo_user_password

Deploy chart as Geo Secondary

This section is performed on the Secondary Kubernetes cluster.

To deploy this chart as a Geo Secondary, start from this example configuration.

  1. Create a secondary.yaml file based on the example configuration and update the configuration to reflect the correct values:

    ## Geo Secondary
    global:
      # See docs.gitlab.com/charts/charts/globals
      # Configure host & domain
      hosts:
        hostSuffix: secondary
        domain: example.com
      # configure DB connection
      psql:
        host: geo-2.db.example.com
        port: 5432
        password:
          secret: geo
          key: postgresql-password
      # configure geo (secondary)
      geo:
        enabled: true
        role: secondary
        nodeName: secondary.example.com
        psql:
          host: geo-2.db.example.com
          port: 5431
          password:
            secret: geo
            key: geo-postgresql-password
    # External DB, disable
    postgresql:
      install: false
    
  2. Deploy the chart using this configuration:

    helm upgrade --install gitlab-geo gitlab/gitlab --namespace gitlab -f secondary.yaml
    
  3. Wait for the deployment to complete, and the application to come online.

Add Secondary Geo instance via Primary

Now that both databases are configured and applications are deployed, we must tell the Primary that the Secondary exists:

  1. Visit the primary instance, and on the top bar, select Menu > Admin.
  2. On the left sidebar, select Geo.
  3. Select New node.
  4. Add the secondary instance. Use the full URL for the URL. Do not select the This is a primary node checkbox.
  5. Enter a Name with the global.geo.nodeName. These values must always match exactly, character for character.
  6. Optionally, choose which groups or storage shards should be replicated by the secondary instance. Leave blank to replicate all.
  7. Select Add node.

After the secondary instance is added to the administration panel, it automatically starts replicating missing data from the primary instance. This process is known as “backfill”. Meanwhile, the primary instance starts to notify each secondary instance of any changes, so that the secondary instance can act on those notifications immediately.

Use Geo proxying for secondary sites

To serve read-write traffic by proxying to the primary site, you can enable Geo secondary proxying and use a single, unified URL for all Geo sites.

Confirm Operational Status

The final step is to verify the Geo replication status on the secondary instance once fully configured, via the Toolbox Pod.

  1. Find the Toolbox Pod:

    kubectl --namespace gitlab get pods -lapp=toolbox
    
  2. Attach to the Pod with kubectl exec:

    kubectl --namespace gitlab exec -ti gitlab-geo-toolbox-XXX -- bash -l
    
  3. Check the status of Geo configuration:

    gitlab-rake gitlab:geo:check
    

    You should see output similar to below:

    WARNING: This version of GitLab depends on gitlab-shell 10.2.0, but you're running Unknown. Please update gitlab-shell.
    Checking Geo ...
    
    GitLab Geo is available ... yes
    GitLab Geo is enabled ... yes
    GitLab Geo secondary database is correctly configured ... yes
    Database replication enabled? ... yes
    Database replication working? ... yes
    GitLab Geo HTTP(S) connectivity ...
    * Can connect to the primary node ... yes
    HTTP/HTTPS repository cloning is enabled ... yes
    Machine clock is synchronized ... Exception: getaddrinfo: Servname not supported for ai_socktype
    Git user has default SSH configuration? ... yes
    OpenSSH configured to use AuthorizedKeysCommand ... no
      Reason:
      Cannot find OpenSSH configuration file at: /assets/sshd_config
      Try fixing it:
      If you are not using our official docker containers,
      make sure you have OpenSSH server installed and configured correctly on this system
      For more information see:
      doc/administration/operations/fast_ssh_key_lookup.md
    GitLab configured to disable writing to authorized_keys file ... yes
    GitLab configured to store new projects in hashed storage? ... yes
    All projects are in hashed storage? ... yes
    
    Checking Geo ... Finished
    
    • Don’t worry about Exception: getaddrinfo: Servname not supported for ai_socktype, as Kubernetes containers do not have access to the host clock. This is OK.
    • OpenSSH configured to use AuthorizedKeysCommand ... no is expected. This Rake task is checking for a local SSH server, which is actually present in the gitlab-shell chart, deployed elsewhere, and already configured appropriately.