OpenEBS for GitLab

    GitLab is a good solution for building On-Premise cloud native CI/CD platforms, it is a single application for the entire software development lifecycle. The helm charts for GitLab are made so simple that the entire infrastructure including the underlying databases and storage needed for GitLab are dynamically provisioned. This solution discusses the use cases of using OpenEBS from a single pool of storage for all the databases required to run GitLab.

    Advantages of using OpenEBS for Gitlab:

    • OpenEBS acts a single storage platform for all stateful applications including Gitaly, Redis, PostgreSQL, Minio and Prometheus

    • OpenEBS volumes are highly available. Node loss, reboots and Kubernetes upgrades will not affect the availability of persistent storage to the stateful applications

    Deployment model

    1. Install OpenEBS

      If OpenEBS is not installed in your K8s cluster, this can done from . If OpenEBS is already installed, go to the next step.

    3. Configure cStor Pool

      After OpenEBS installation, cStor pool has to be configured. If cStor Pool is not configured in your OpenEBS cluster, this can be done from here. During cStor Pool creation, make sure that the maxPools parameter is set to >=3. Sample YAML named openebs-config.yaml for configuring cStor Pool is provided in the Configuration details below. If cStor pool is already configured, go to the next step.

    4. Create Storage Class

      You must configure a StorageClass to provision cStor volume on given cStor pool. StorageClass is the interface through which most of the OpenEBS storage policies are defined. In this solution we are using a StorageClass to consume the cStor Pool which is created using external disks attached on the Nodes. Since GitLab is a StatefulSet application and it requires only single storage replication. So cStor volume is =1. Sample YAML named openebs-sc-disk.yamlto consume cStor pool with cStoveVolume Replica count as 1 is provided in the configuration details below.

    5. Launch and test GitLab

      Patch your StorageClass which is going to be used for the GitLab installation using the following command.

      Use stable Gitlab image with helm to deploy GitLab in your cluster using the following command. In the following command, it will create two PVCs such as 1Gi for storing generated configuration files, keys, and certs and 10Gi is used to store git data and other project files.

      For more information on installation, see GitLab .

    Post deployment Operations

    Monitor OpenEBS Volume size

    It is not seamless to increase the cStor volume size (refer to the roadmap item). Hence, it is recommended that sufficient size is allocated during the initial configuration. However, an alert can be setup for volume size threshold using Kubera.

    Monitor cStor Pool size

    As in most cases, cStor pool may not be dedicated to just GitLab’s databases alone. It is recommended to watch the pool capacity and add more disks to the pool before it hits 80% threshold. See .

    Maintain volume replica quorum during node upgrades

    cStor volume replicas need to be in quorum when applications are deployed as and cStor volume is configured to have . Node reboots may be common during Kubernetes upgrade. Maintain volume replica quorum in such instances. See here for more details.

    openebs-config.yaml

    openebs-sc-disk.yaml

    See Also: