Storage

Brigade utilizes storage in the following ways:

Shared Worker storage wherein a Brigade Worker’s workspace may be shared with and among its Jobs
Artemis storage for Brigade’s Messaging/Queue component
MongoDB storage for Brigade’s backing data store

Shared Worker storage

The workspace for a Brigade Worker can be shared among all Worker Jobs. This is an opt-in feature and isn’t enabled by default. When enabled, Brigade will create a PersistentVolume on the underlying Kubernetes cluster and automatically add the corresponding volume mount to each Worker Job created.

Note: As this volume may be accessed by more than one pod, and each pod may need both read and write access to the shared volume, its access mode is ReadWriteMany, which may not be supported by the default storage class configured on your Kubernetes cluster. See the Access Modes matrix for compatibility. Brigade is well-tested using NFS and Azure File on AKS. (Azure Disk does not support this required access mode.)

For Brigade Worker storage, it is often convenient to use storage backends that are optimized for short-term ephemeral storage. To that end, Brigade ships with its default configured as NFS (Network File System). Therefore, NFS will need to be deployed on the same Kubernetes cluster as Brigade. You can use the NFS Server Provisioner chart for this purpose:

$ helm repo add stable ttps://charts.helm.sh/stable
$ helm install nfs stable/nfs-server-provisioner \
  --create-namespace --namespace nfs

By default, the NFS chart installs with persistance disabled. For various methods on enabling, as well as configuring other aspects of the installation, see the README.

This chart installs a StorageClass named nfs. As mentioned, Brigade already has worker.storageClass set to nfs in its Helm chart values file. To configure an alternate storage class, set this field’s value to the preferred storage class name. For example, to use the Azure File storage class, the appropriate configuration would be:

worker:
  workspaceStorageClass: azurefile

Enabling Worker storage

To enable shared Worker storage, set useWorkspace to true under the workerTemplate section on the project configuration file (usually project.yaml) for a Project. For example, here is the relevant bit of configuration from the 08-shared-workspace example project:

spec:
  workerTemplate:
    useWorkspace: true

Each Worker Job requiring access to this workspace must then be configured with a filepath value designating where the workspace should be mounted within the Job’s container. (Note that this may be the Job’s primaryContainer and/or one or more of a Job’s sidecarContainer(s)). This filepath value is assigned to the workspaceMountPath field on each applicable Job container.

In the example brigade.js script below, the both Jobs are configured with the workspaceMountPath value set to /share. Thus, second-job is able to read (and display) the message that first-job emits, via the shared workspace mount:

const { events, Job } = require("@brigadecore/brigadier");

events.on("brigade.sh/cli", "exec", async event => {
  let job1 = new Job("first-job", "debian:latest", event);
  job1.primaryContainer.workspaceMountPath = "/share";
  job1.primaryContainer.command = ["bash"];
  job1.primaryContainer.arguments = ["-c", "echo 'Hello!' > /share/message"];
  await job1.run();

  let job2 = new Job("second-job", "debian:latest", event);
  job2.primaryContainer.workspaceMountPath = "/share";
  job2.primaryContainer.command = ["cat"];
  job2.primaryContainer.arguments = ["/share/message"];
  await job2.run();
});

events.process();

Artemis storage

Brigade uses ActiveMQ Artemis as its messaging queue component. For more details on its function in Brigade, see the Design doc.

Messages (i.e. work to be scheduled on Kubernetes) should be persisted even if/when Artemis itself goes down or is restarted. Therefore, by default, persistence is enabled via the appropriate configuration on the Brigade Helm Chart. The default access mode for the backing PersistentVolume is ReadWriteOnce. This mode, although configurable, should not need changing.

There are, however, other persistence options that may be useful to customize, such as volume size and storage class type. Regarding volume size, the default is a fairly small 8Gi, which is not considered adequate for a production deployment and should be updated accordingly. All configuration options can be seen under the artemis.persistence section of the Brigade chart.

As the access mode is ReadWriteOnce, nearly all storage class types should function correctly for this PersistentVolume. By default, no storage class is specified in the chart, which means the default storage class on the Kubernetes cluster will be employed.

MongoDB storage

Brigade uses MongoDB as its backing data store. For more details on its function in Brigade, see the Design doc.

Data should be persisted even when/if MongoDB itself goes down or is restarted. Therefore, by default, persistence is enabled via the appropriate configuration on the Brigade Helm Chart. The default access mode for the backing PersistentVolume is ReadWriteOnce. This mode, although configurable, should not need changing.