Piraeus Datastore - HA Datastore for Kubernetes

Piraeus is a high performance (i.e., in Linux kernel), highly-available, simple, secure, and cloud agnostic data store for Kubernetes.

Getting started

Requirements

Using a Kubernetes cluster with at least 4 worker nodes is recommended. Due to CSI compatibility, kubelet version must be one of:

• v1.14.x
• v1.15.x
• v1.16.x
• v1.17.x

The hosts should use Docker as their container runtime and be running one of the following distributions to enable automatic DRBD kernel module injection:

• CentOS/RHEL 7
• CentOS/RHEL 8
• Ubuntu 16
• Ubuntu 18

Node selection

The nodes on which piraeus should provide or consume storage should be labelled as follows:

kubectl label nodes $NODE_NAME piraeus/node=true

These nodes must also have the appropriate kernel development package installed unless DRBD is already present. This is kernel-devel for CentOS based distributions and linux-headers-`uname -r` for Ubuntu.

Installation

Install as follows:

kubectl apply -f https://raw.githubusercontent.com/piraeusdatastore/piraeus/master/deploy/all.yaml

This may take several minutes. Once the pods have started, the status of Piraeus can be checked with:

kubectl -n kube-system exec piraeus-controller-0 -- linstor node list

This should show that the selected nodes are Online at the LINSTOR level.

Using storage (demo)

Piraeus preconfigures a DfltStorPool by using LINSTOR's FileThin backend, which is ready to use after yaml deployment.

The demo directory contains examples of how to use DfltStorPool. For instance:

kubectl apply -f https://raw.githubusercontent.com/piraeusdatastore/piraeus/master/demo/demo-sts.yaml

This demo statefulset is a 3-node MySQL cluster. Demo pods and pvcs are under piraeus namespace.

Storage configuration

Piraeus can use storage that is local to the application as well as storage on other nodes. On the nodes that should provide storage, backing devices must be available. Assuming the hosts have empty storage devices of at least 1GB capacity, they can be listed as follows:

kubectl -n kube-system exec piraeus-controller-0 -- linstor physical-storage list

Piraeus can then configure LVM on these devices and create a storage pool. Use the following steps for each node:

kubectl -n kube-system exec piraeus-controller-0 -- linstor physical-storage create-device-pool --pool-name pool0 LVM $NODE_NAME /dev/$DEVICE
kubectl -n kube-system exec piraeus-controller-0 -- linstor storage-pool create lvm $NODE_NAME DfltStorPool pool0

Components

Piraeus consists of a number of open source components.

DRBD

DRBD is used as the underlying storage replication mechanism. Documentation is provided by LINBIT.

LINSTOR

LINSTOR is used for storage management. Documentation is provided by LINBIT.

LINSTOR CSI Plugin

The LINSTOR CSI plugin integrates LINSTOR with the Container Storage Interface. Documentation is included with the LINSTOR documentation.

Structure of this repository

dockerfiles

This directory contains Dockerfiles and shell scripts for Piraeus components. Each of the subdirectories has a README.md with more information.

• drbd-driver-loader contains is a collection of Piraeus container images containing the DRBD kernel source code that can be used to compile DRBD kernel modules from source and load them into the host kernel.
• piraeus-server combines LINBIT's linstor-controller and linstor-satellite components, as well as the linstor-client which can be used for cluster setup. It also contains some useful debugging tools.
• piraeus-client is a stand alone version of the linstor-client.