Overview

This charm provides the Glance image service for OpenStack. It is intended to be used alongside the other OpenStack components.

Usage

Glance may be deployed in a number of ways. This charm focuses on 3 main configurations. All require the existence of the other core OpenStack services deployed via Juju charms, specifically: mysql, keystone and nova-cloud-controller. The following assumes these services have already been deployed.

Local Storage

In this configuration, Glance uses the local storage available on the server to store image data:

juju deploy glance
juju add-relation glance keystone
juju add-relation glance mysql
juju add-relation glance nova-cloud-controller

Swift backed storage

Glance can also use Swift Object storage for image storage. Swift is often deployed as part of an OpenStack cloud and provides increased resilience and scale when compared to using local disk storage. This configuration assumes that you have already deployed Swift using the swift-proxy and swift-storage charms:

juju deploy glance
juju add-relation glance keystone
juju add-relation glance mysql
juju add-relation glance nova-cloud-controller
juju add-relation glance swift-proxy

This configuration can be used to support Glance in HA/Scale-out deployments.

Ceph backed storage

In this configuration, Glance uses Ceph based object storage to provide scalable, resilient storage of images. This configuration assumes that you have already deployed Ceph using the ceph charm:

juju deploy glance
juju add-relation glance keystone
juju add-relation glance mysql
juju add-relation glance nova-cloud-controller
juju add-relation glance ceph

This configuration can also be used to support Glance in HA/Scale-out deployments.

NOTE: Glance acts as a Ceph client in this case which requires IP (L3) connectivity to ceph monitors and OSDs. For MAAS-based deployments this can be addressed with network spaces (see the relevant section below).

HA/Clustering

There are two mutually exclusive high availability options: using virtual IP(s) or DNS. In both cases, a relationship to hacluster is required which provides the corosync back end HA functionality.

To use virtual IP(s) the clustered nodes must be on the same subnet such that the VIP is a valid IP on the subnet for one of the node's interfaces and each node has an interface in said subnet. The VIP becomes a highly-available API endpoint.

At a minimum, the config option 'vip' must be set in order to use virtual IP HA. If multiple networks are being used, a VIP should be provided for each network, separated by spaces. Optionally, vip_iface or vip_cidr may be specified.

To use DNS high availability there are several prerequisites. However, DNS HA does not require the clustered nodes to be on the same subnet. Currently the DNS HA feature is only available for MAAS 2.0 or greater environments. MAAS 2.0 requires Juju 2.0 or greater. The clustered nodes must have static or "reserved" IP addresses registered in MAAS. The DNS hostname(s) must be pre-registered in MAAS before use with DNS HA.

At a minimum, the config option 'dns-ha' must be set to true and at least one of 'os-public-hostname', 'os-internal-hostname' or 'os-internal-hostname' must be set in order to use DNS HA. One or more of the above hostnames may be set.

The charm will throw an exception in the following circumstances: If neither 'vip' nor 'dns-ha' is set and the charm is related to hacluster If both 'vip' and 'dns-ha' are set as they are mutually exclusive If 'dns-ha' is set and none of the os-{admin,internal,public}-hostname(s) are set

Note that Glance in HA configuration must be used with either Ceph or Swift providing backing image storage.

Glance metering

In order to do Glance metering with Ceilometer, an AMQP relation is required e.g.

juju deploy glance
juju deploy rabbitmq-server
juju deploy ceilometer-agent
...
juju add-relation glance rabbitmq-server
juju add-relation glance ceilometer-agent
...

Network Space support

This charm supports the use of Juju Network Spaces, allowing the charm to be bound to network space configurations managed directly by Juju. This is only supported with Juju 2.0 and above.

API endpoints can be bound to distinct network spaces supporting the network separation of public, internal and admin endpoints.

Glance acts as a Ceph client and needs IP connectivity to Ceph monitors and OSDs. Binding the ceph endpoint to a space can solve this problem in case monitors and OSDs are located on a single L2 broadcast domain (if they are not, static or dynamic routes need to be used in addition to spaces).

Access to the underlying MySQL instance can also be bound to a specific space using the shared-db relation.

To use this feature, use the --bind option when deploying the charm:

juju deploy glance --bind "public=public-space internal=internal-space admin=admin-space shared-db=internal-spacec ceph=ceph-access-space"

Alternatively, these can also be provided as part of a juju native bundle configuration:

glance:
  charm: cs:xenial/glance
  num_units: 1
  bindings:
    public: public-space
    admin: admin-space
    internal: internal-space
    shared-db: internal-space
    ceph: ceph-access-space

NOTE: Spaces must be configured in the underlying provider prior to attempting to use them.

NOTE: Existing deployments using os-*-network configuration options will continue to function; these options are preferred over any network space binding provided if set.

Policy Overrides

This feature allows for policy overrides using the policy.d directory. This is an advanced feature and the policies that the OpenStack service supports should be clearly and unambiguously understood before trying to override, or add to, the default policies that the service uses. The charm also has some policy defaults. They should also be understood before being overridden.

Caution

: It is possible to break the system (for tenants and other services) if policies are incorrectly applied to the service.

Policy overrides are YAML files that contain rules that will add to, or override, existing policy rules in the service. The policy.d directory is a place to put the YAML override files. This charm owns the /etc/keystone/policy.d directory, and as such, any manual changes to it will be overwritten on charm upgrades.

Overrides are provided to the charm using a Juju resource called policyd-override. The resource is a ZIP file. This file, say overrides.zip, is attached to the charm by:

juju attach-resource glance policyd-override=overrides.zip

The policy override is enabled in the charm using:

juju config glance use-policyd-override=true

When use-policyd-override is True the status line of the charm will be prefixed with PO: indicating that policies have been overridden. If the installation of the policy override YAML files failed for any reason then the status line will be prefixed with PO (broken):. The log file for the charm will indicate the reason. No policy override files are installed if the PO (broken): is shown. The status line indicates that the overrides are broken, not that the policy for the service has failed. The policy will be the defaults for the charm and service.

Policy overrides on one service may affect the functionality of another service. Therefore, it may be necessary to provide policy overrides for multiple service charms to achieve a consistent set of policies across the OpenStack system. The charms for the other services that may need overrides should be checked to ensure that they support overrides before proceeding.