kolla/doc/architecture-guide.rst

Production architecture guide

This guide will help with configuring Kolla to suit production needs. It is meant to answer some questions regarding basic configuration options that Kolla requires. This document also contains other useful pointers.

Node types and services running on them

A basic Kolla inventory consists of several types of nodes, known in Ansible as groups.

• Controller - This is the cloud controller node. It hosts control services like APIs and databases. This group should have odd number of nodes for quorum.
• Network - This is the network node. It will host Neutron agents along with haproxy / keepalived. These nodes will have a floating ip defined in Kolla_internal_vip_address.
• Compute - These are servers for compute services. This is where guest VMs live.
• Storage - Storage servers, for cinder-volume, LVM or ceph-osd.

Network configuration

Interface configuration

In Kolla operators should configure following network interfaces:

• network_interface - While it is not used on it's own, this provides the required default for other interfaces below.
• api_interface - This interface is used for the management network. The management network is the network OpenStack services uses to communicate to each other and the databases. There are know security risks here, so it's recommended to make this network internal, not accessible from outside. Defaults to network_interface.
• kolla_external_vip_interface - This interface is public-facing one. It's used when you want HAProxy public endpoints to be exposed in different network than internal ones. It is mandatory to set this option when kolla_enable_tls_external is set to yes. Defaults to network_interface.
• storage_interface - This is the interface that is used by virtual machines to communicate to Ceph. This can be heavily utilized so it's recommended to put this network on 10Gig networking. Defaults to network_interface.
• cluster_interface - This is another interface used by Ceph. It's used for data replication. It can be heavily utilized also and if it becomes a bottleneck it can affect data consistency and performance of whole cluster. Defaults to network_interface.
• tunnel_interface - This interface is used by Neutron for vm-to-vm traffic over tunneled networks (like VxLan). Defaults to network_interface.
• Neutron_external_interface - This interface is required by Neutron. Neutron will put br-ex on it. It will be used for flat networking as well as tagged vlan networks. Has to be set separately.

Docker configuration

Because Docker is core dependency of Kolla, proper configuration of Docker can change the experience of Kolla significantly. Following section will highlight several Docker configuration details relevant to Kolla operators.

Storage driver

In certain distributions Docker storage driver defaults to devicemapper, which can heavily hit performance of builds and deploys. We suggest to use btrfs or aufs as driver. More details on which storage driver to use in Docker documentation.

Volumes

Kolla puts nearly all of persistent data in Docker volumes. These volumes are created in Docker working directory, which defaults to

/var/lib/docker

We recommend to ensure that this directory has enough space and is placed on fast disk as it will affect performance of builds, deploys as well as database commits and rabbitmq.

This becomes especially relevant when enable_central_logging and openstack_logging_debug are both set to true, as fully loaded 130 node cluster produced 30-50GB of logs daily.