General Architecture Overview

This document outlines the main aspects of Kublr’s general architecture. Kublr is a Kubernetes management platform which accelerates and controls the deployment, scaling, monitoring and management of Kubernetes clusters.

The diagram below describes two main Kublr deployment types:

  1. Kublr Platform (centralized management platform for Kubernetes clusters)
  2. Kublr Cluster

Kublr Control Plane

The Kublr Platform (at the top-left) is the main management portal for your Kubernetes clusters.

It runs on a Kublr cluster which is basically a standard Kubernetes cluster but with additional components.

The Kublr Platform provides an integrated set of the applications running in a Kublr cluster. They include:

  1. Control Plane / UI: the management interface from which users create, view, edit, and delete clusters. Additionally, it provides access to other user interfaces, like backup, KeyCloak, Grafana and Kibana.
  2. Centralized Monitoring: based on Prometheus and Grafana it collects metrics from all clusters deployed with Kublr, including cloud, hardware, OS, kubernetes, and applications metrics.
  3. Centralized Logging: based on the standard ELK (Elasticsearch, LogStash Kibana) stack, Kublr centrally collects logs from all clusters, including hardware, OS, Kubernetes, and containers metrics. Additionally, it collects audit logs components ensuring traceability and audit of all user actions.
  4. IAM, JBoss Keycloak: open source identity and access management (IAM) provides user management. Additionally, Kublr integrates with LDAP/AD, 2FA and other enterprise authentication tools. The identity broker is responsible for user management, brokering integration with external users and identity providers (SAML, OIDC, LDAP, AD) as well as authenticating users in Kublr and Kublr managed Kubernetes clusters.
  5. Backup Controller: is the component responsible for cluster backups, purging old backups and restoration of the clusters from backup snapshots. Cluster backup snapshots include both Kubernetes metadata and application data.

The Kublr cluster is the main management object for the Kublr Platform. Kublr configures four architectural layers. After being correctly setup and configured (usually by a higher layer), each layer is self-sufficient, self-healing and self-reliant. As long as the underlying infrastructure and layers are functional, each layer functions without interruptions.

Kublr Control Plane

Layers at play:

The infrastructure layer includes virtual and/or physical machines/servers hosted in a datacenter or in a cloud (e.g. AWS, Azure). Kublr sets up and manages Kubernetes on top of virtually any infrastructure and multiple OS’s, though some types of infrastructure providers allow for better automation than others. When setting up instances on any environment—whether a Kubernetes master or node—Kublr ensures they are fully replaceable should an instance failure occur.

In AWS and Azure, Kublr enables self-healing on an infrastructure level via AWS’ auto-scaling groups and Azure’s VM auto-restart. On premise virtual and physical machines, can easily be replaced manually or through infrastructure automation tools of choice in case of a failure.

The Kubernetes layer includes all standard Kubernetes components - etcd cluster, Kubernetes master components (API, scheduler, controller manager etc.), kubelet, kube-proxy, various Kubernetes add-ons, such as DNS, dashboard, overlay network provider, auto scaler etc.

Kublr sets up and connects Kubernetes components on each instance so that communication between them is secure, reliable, and able to recover from failures as long as and as soon as the underlying infrastructure is recovered.

Kublr uses unmodified standard Kubernetes components and Kubernetes configuration best practices ensuring secure, reliable, and standard conformant Kubernetes setup.

The Kublr Agent is a single binary running as a service on every Kublr instance, both masters and nodes, managed the Kubernetes cluster.

The Kublr Agent is then responsible for configuring Kubernetes components on the machines and connecting them into a Kubernetes cluster as described above.

As a result, a new Kubernetes cluster is started on the provisioned infrastructure and connected to the Kublr Control Plane with centralized authentication, monitoring, and logging.

The Kublr agent’s responsibilities include:

  1. Setup and configuration of auxiliary software packages on instances and infrastructure resources for the instances, such as etcd EBS volume attachment and initialization on AWS environment;
  2. Initialization, distribution (through secret store, such as private S3 bucket or Azure storage), and rotation of shared configuration and security data, such as various certificates, keys, tokens etc. required for a secure Kubernetes setup;
  3. Initial setup and configuration of Kubernetes components including Docker, etcd, Kubernetes master components, kubelet, kube-proxy, essential add-ons, and overlay network provider components;

In addition, Kublr provides: Local logging component - responsible for collecting Kubernetes and pods logs to pass them further to Kublr Platform.

Diagram below depicts main components of Kublr Cluster and Kubernetes:

Kublr Control Plane

Centralized Monitoring

Kublr’s centralized monitoring capabilitiy is built on top of the Prometheus and Grafana. Each cluster is registered as a metrics source in Prometheus. Kubernetes provides cloud, hardware, OS, Kubernetes, and applications metrics using the Kubernetes API of each cluster respectively. Kublr manages metrics source lists in Prometheus, and Grafana’s single sign-on integration with the Kublr Control Plane, provides easy access to key dashboards. The centralized monitoring component is deployed as a Helm package.

Centralized Monitoring

Centralized Log Collection

Kublr’s centralized log collection capability is built on top of the Elasticsearch, Logstash, and Kibana stack. In addition, for better resilience RabbitMQ is used to accamulate the remaining log entries between sync up sessions. On a Kublr cluster level, Helm package with RabbitMQ, FluentD and haproxy are deployed. FluentD collects log entries from all levels: hardware, OS, pods, Kubernetes and Kublr core components. RabbitMQ is configured to be the primary destination for all collected logs and haproxy used for data channels between the Kublr Platform and Kublr clusters through Kubernetes port-forwarding feature.

On the Kublr Platform side, the kublr-central-logging helm package includes Elasticsearch, Kibana, Logstash with RabbitMQ and the RabbitMQ Shovel plugin. The latter transfers messages to the centralized RabbitMQ where they are digested by Logstash and stored in Elasticsearch. Kibana, integrated with Kublr through single sign-on, provides a convenient UI to access and search log entries from all clusters.

In addition to centralized log collection, local Elasticsearch and Kibana may be installed by the user. They act in parallel with centralized log collection mechanism.

Centralized Log Collection

Kublr Backup Controller

The Kublr Backup Controller is deployed as a Kubernetes application. It’s main responsibility is making volume snapshots from all volumes attached to the clusters as specified in the backup schedule. Additionally, the Backup Controller is also responsible for purging old backup snapshots and cluster restoration logic from provided snapshot.