Tungsten Fabric cluster components

This section describes the Tungsten Fabric services and their distribution across the Mirantis OpenStack for Kubernetes (MOSK) deployment.

The Tungsten Fabric services run mostly as DaemonSets in separate containers for each service. The deployment and update processes are managed by the Tungsten Fabric Operator. However, Kubernetes manages the probe checks and restart of broken containers.

Configuration and control services

All configuration and control services run on the Tungsten Fabric Controller nodes.

Service name	Service description
`config-api`	Exposes a REST-based interface for the Tungsten Fabric API.
`config-provisioner`	Provisions the node for execution of configuration services.
`control`	Communicates with the cluster gateways using BGP and with the vRouter agents using XMPP, as well as redistributes appropriate networking information.
`control-provisioner`	Provisions the node for execution of configuration services.
`device-manager`	Manages physical networking devices using `netconf` or `ovsdb`. In multi-node deployments, it operates in the active-backup mode.
`dns`	Using the `named` service, provides the DNS service to the VMs spawned on different compute nodes. Each vRouter node connects to two Tungsten Fabric Controller containers that run the `dns` process.
`named`	The customized Berkeley Internet Name Domain (BIND) daemon of Tungsten Fabric that manages DNS zones for the `dns` service.
`schema`	Listens to configuration changes performed by a user and generates corresponding system configuration objects. In multi-node deployments, it works in the active-backup mode.
`svc-monitor`	Listens to configuration changes of `service-template` and `service-instance`, as well as spawns and monitors virtual machines for the firewall, analyzer services, and so on. In multi-node deployments, it works in the active-backup mode.
`webui`	Consists of the `webserver` and `jobserver` services. Provides the Tungsten Fabric web UI.

vRouter

The Tungsten Fabric vRouter provides data forwarding to an OpenStack tenant instance and reports statistics to the Tungsten Fabric analytics service. The Tungsten Fabric vRouter is installed on all OpenStack compute nodes. Mirantis OpenStack for Kubernetes (MOSK) supports the kernel-based deployment of the Tungsten Fabric vRouter.

vRouter services on the OpenStack compute nodes
Service name	Service description
`vrouter-agent`	Connects to the Tungsten Fabric Controller container and the Tungsten Fabric DNS system using the Extensible Messaging and Presence Protocol (XMPP). The vRouter Agent acts as a local control plane. Each Tungsten Fabric vRouter Agent is connected to at least two Tungsten Fabric controllers in an active-active redundancy mode. The Tungsten Fabric vRouter Agent is responsible for all networking-related functions including routing instances, routes, and others. The Tungsten Fabric vRouter uses different gateways for the control and data planes. For example, the Linux system gateway is located on the management network, and the Tungsten Fabric gateway is located on the data plane network.
`vrouter-provisioner`	Provisions the node for the vRouter agent execution.

The following diagram illustrates the Tungsten Fabric kernel vRouter set up by the TF operator:

On the diagram above, the following types of networks interfaces are used:

eth0 - for the management (PXE) network (eth1 and eth2 are the slave interfaces of Bond0)
Bond0.x - for the MKE control plane network
Bond0.y - for the MKE data plane network

Third-party services

Service name	Service description
`cassandra`	On the Tungsten Fabric control plane nodes, maintains the configuration data of the Tungsten Fabric cluster. On the Tungsten Fabric analytics nodes, stores the `collector` service data.
`cassandra-operator`	The Kubernetes operator that enables the Cassandra clusters creation and management.
`redis`	Stores the physical router UVE storage and serves as a messaging bus for event notifications.
`redis-operator`	The Kubernetes operator that enables Redis clusters creation and management.
`zookeeper`	Holds the active-backup status for the `device-manager`, `svc-monitor`, and the `schema-transformer` services. This service is also used for mapping of the Tungsten Fabric resources names to UUIDs.
`zookeeper-operator`	The Kubernetes operator that enables ZooKeeper clusters creation and management.
`rabbitmq`	Exchanges messages between API servers and original request senders.
`rabbitmq-operator`	The Kubernetes operator that enables RabbitMQ clusters creation and management.

Plugin services

All Tungsten Fabric plugin services are installed on the OpenStack Controller (Rockoon) nodes.

Service name	Service description
`neutron-server`	The Neutron server that includes the Tungsten Fabric plugin.
`octavia-api`	The Octavia API that includes the Tungsten Fabric Octavia driver.
`heat-api`	The Heat API that includes the Tungsten Fabric Heat resources and templates.

Image precaching DaemonSets

Along with the Tungsten Fabric services, MOSK deploys and updates special image precaching DaemonSets when the kind TFOperator resource is created or image references in it get updated. These DaemonSets precache container images on Kubernetes nodes minimizing possible downtime when updating container images. Cloud operator can disable image precaching through the TFOperator resource.