Streamline README for policy overrides
The appendix in the deploy-guide has recently been refreshed. This is the seventh of the nine charms that support overrides to receive a streamlining in order to cut down on duplication. Some driveby formatting improvements. Added a Bugs section. Change-Id: I8c7c86a0705b22f73a30475f4a5495d7fb40426f
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Peter Matulis
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README.md
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README.md
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# nova-cloud-controller
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# Overview
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Cloud controller node for OpenStack nova. Contains nova-schedule, nova-api, nova-network and nova-objectstore.
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Cloud controller node for OpenStack nova. Contains nova-schedule, nova-api,
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nova-network and nova-objectstore.
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If console access is required then console-proxy-ip should be set to a client accessible IP that resolves
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to the nova-cloud-controller. If running in HA mode then the public vip is used if console-proxy-ip is set
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to local. Note: The console access protocol is baked into a guest when it is created, if you change it then
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console access for existing guests will stop working
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If console access is required then console-proxy-ip should be set to a client
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accessible IP that resolves to the nova-cloud-controller. If running in HA mode
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then the public vip is used if console-proxy-ip is set to local. Note: The
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console access protocol is baked into a guest when it is created, if you change
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it then console access for existing guests will stop working
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# Usage
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## HA/Clustering
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There are two mutually exclusive high availability options: using virtual
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IP(s) or DNS. In both cases, a relationship to hacluster is required which
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provides the corosync back end HA functionality.
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There are two mutually exclusive high availability options: using virtual IP(s)
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or DNS. In both cases, a relationship to hacluster is required which provides
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the corosync back end HA functionality.
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To use virtual IP(s) the clustered nodes must be on the same subnet such that
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the VIP is a valid IP on the subnet for one of the node's interfaces and each
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@ -24,36 +28,45 @@ network, separated by spaces. Optionally, vip_iface or vip_cidr may be
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specified.
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To use DNS high availability there are several prerequisites. However, DNS HA
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does not require the clustered nodes to be on the same subnet.
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Currently the DNS HA feature is only available for MAAS 2.0 or greater
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environments. MAAS 2.0 requires Juju 2.0 or greater. The clustered nodes must
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have static or "reserved" IP addresses registered in MAAS. The DNS hostname(s)
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must be pre-registered in MAAS before use with DNS HA.
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does not require the clustered nodes to be on the same subnet. Currently the
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DNS HA feature is only available for MAAS 2.0 or greater environments. MAAS 2.0
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requires Juju 2.0 or greater. The clustered nodes must have static or
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"reserved" IP addresses registered in MAAS. The DNS hostname(s) must be
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pre-registered in MAAS before use with DNS HA.
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At a minimum, the config option 'dns-ha' must be set to true and at least one
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of 'os-public-hostname', 'os-internal-hostname' or 'os-internal-hostname' must
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be set in order to use DNS HA. One or more of the above hostnames may be set.
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The charm will throw an exception in the following circumstances:
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If neither 'vip' nor 'dns-ha' is set and the charm is related to hacluster
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If both 'vip' and 'dns-ha' are set as they are mutually exclusive
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If 'dns-ha' is set and none of the os-{admin,internal,public}-hostname(s) are
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set
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The charm will throw an exception in the following circumstances: If neither
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'vip' nor 'dns-ha' is set and the charm is related to hacluster If both 'vip'
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and 'dns-ha' are set as they are mutually exclusive If 'dns-ha' is set and none
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of the os-{admin,internal,public}-hostname(s) are set
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## Network Space support
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## Spaces
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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.
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This charm supports the use of Juju Network Spaces, allowing the charm to be
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bound to network space configurations managed directly by Juju. This is only
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supported with Juju 2.0 and above.
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API endpoints can be bound to distinct network spaces supporting the network separation of public, internal and admin endpoints.
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API endpoints can be bound to distinct network spaces supporting the network
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separation of public, internal and admin endpoints.
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Access to the underlying MySQL instance can also be bound to a specific space using the shared-db relation.
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Access to the underlying MySQL instance can also be bound to a specific space
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using the shared-db relation.
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To use this feature, use the --bind option when deploying the charm:
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juju deploy nova-cloud-controller --bind "public=public-space internal=internal-space admin=admin-space shared-db=internal-space"
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juju deploy nova-cloud-controller --bind \
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"public=public-space \
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internal=internal-space \
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admin=admin-space \
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shared-db=internal-space"
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alternatively these can also be provided as part of a juju native bundle configuration:
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Alternatively, these can also be provided as part of a Juju native bundle
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configuration:
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```yaml
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nova-cloud-controller:
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charm: cs:xenial/nova-cloud-controller
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num_units: 1
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@ -62,110 +75,108 @@ alternatively these can also be provided as part of a juju native bundle configu
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admin: admin-space
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internal: internal-space
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shared-db: internal-space
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```
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NOTE: Spaces must be configured in the underlying provider prior to attempting to use them.
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NOTE: Spaces must be configured in the underlying provider prior to attempting
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to use them.
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NOTE: Existing deployments using os-*-network configuration options will continue to function; these options are preferred over any network space binding provided if set.
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NOTE: Existing deployments using os-*-network configuration options will
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continue to function; these options are preferred over any network space
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binding provided if set.
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## Default Quota Configuration
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This charm supports default quota settings for projects.
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This feature is only available from Openstack Icehouse and later releases.
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This charm supports default quota settings for projects. This feature is only
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available from OpenStack Icehouse and later releases.
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The default quota settings do not overwrite post-deployment CLI quotas set by operators.
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Existing projects whose quotas were not modified will adopt the new defaults when a config-changed hook occurs.
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Newly created projects will also adopt the defaults set in the charm's config.
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The default quota settings do not overwrite post-deployment CLI quotas set by
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operators. Existing projects whose quotas were not modified will adopt the new
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defaults when a config-changed hook occurs. Newly created projects will also
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adopt the defaults set in the charm's config.
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By default, the charm's quota configs are not set and openstack projects have the values below as default:
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quota-instances - 10
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quota-cores - 20
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quota-ram - 51200
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quota-metadata_items - 128
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quota-injected_files - 5
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quota-injected_file_content_bytes - 10240
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quota-injected_file_path_length - 255
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quota-key_pairs - 100
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quota-server_groups - 10 (only available after Icehouse)
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quota-server_group_members - 10 (only available after Icehouse)
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By default, the charm's quota configs are not set and OpenStack projects have
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the below default values:
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quota-instances : 10
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quota-cores : 20
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quota-ram : 51200
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quota-metadata_items : 128
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quota-injected_files : 5
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quota-injected_file_content_bytes : 10240
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quota-injected_file_path_length : 255
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quota-key_pairs : 100
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quota-server_groups : 10 (available since Juno)
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quota-server_group_members : 10 (available since Juno)
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## SSH knownhosts caching
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This section covers the option involving the caching of SSH host lookups
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(knownhosts) on each nova-compute unit. Caching of SSH host lookups speeds up
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(knownhosts) on each nova-compute unit. Caching of SSH host lookups speeds up
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deployment of nova-compute units when first deploying a cloud, and when adding
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a new unit.
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There is a Boolean configuration key `cache-known-hosts` that ensures that any
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given host lookup to be performed just once. The default is `true` which means
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given host lookup to be performed just once. The default is `true` which means
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that caching is performed.
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**Note**: A cloud can be deployed with the `cache-known-hosts` key set to
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`false`, and be set to `true` post-deployment. At that point the hosts
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will have been cached. The key only controls whether the cache is used or
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not.
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> **Note**: A cloud can be deployed with the `cache-known-hosts` key set to
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`false`, and be set to `true` post-deployment. At that point the hosts will
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have been cached. The key only controls whether the cache is used or not.
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If the above key is set, a new Juju action `clear-unit-knownhost-cache` is
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provided to clear the cache. This can be applied to a unit, service, or an
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entire nova-cloud-controller application. This would be needed if DNS
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resolution had changed in an existing cloud or during a cloud deployment.
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Not clearing the cache in such cases could result in an inconsistent set
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of knownhosts files.
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resolution had changed in an existing cloud or during a cloud deployment. Not
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clearing the cache in such cases could result in an inconsistent set of
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knownhosts files.
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This action will cause DNS resolution to be performed (for
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unit/service/application), thus potentially triggering a relation-set on
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the nova-cloud-controller unit(s) and subsequent changed hook on the
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related nova-compute units.
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unit/service/application), thus potentially triggering a relation-set on the
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nova-cloud-controller unit(s) and subsequent changed hook on the related
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nova-compute units.
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The action is used as follows, based on unit, service, or application,
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respectively:
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```
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juju run-action nova-cloud-controller/0 clear-unit-knownhost-cache target=nova-compute/2
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juju run-action nova-cloud-controller/0 clear-unit-knownhost-cache target=nova-compute
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juju run-action nova-cloud-controller/0 clear-unit-knownhost-cache
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```
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juju run-action nova-cloud-controller/0 clear-unit-knownhost-cache target=nova-compute/2
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juju run-action nova-cloud-controller/0 clear-unit-knownhost-cache target=nova-compute
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juju run-action nova-cloud-controller/0 clear-unit-knownhost-cache
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In a high-availability setup, the action must be run on all
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`nova-cloud-controller` units.
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# Policy Overrides
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## Policy Overrides
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This feature allows for policy overrides using the `policy.d` directory. This
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is an **advanced** feature and the policies that the OpenStack service supports
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should be clearly understood before trying to override, or add to, the default
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policies that the service uses. The charm also has some policy defaults. They
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should also be understood before being overridden.
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Policy overrides is an **advanced** feature that allows an operator to override
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the default policy of an OpenStack service. The policies that the service
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supports, the defaults it implements in its code, and the defaults that a charm
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may include should all be clearly understood before proceeding.
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> **Caution**: It is possible to break the system (for tenants and other
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services) if policies are incorrectly applied to the service.
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Policy overrides are YAML files that contain rules that will add to, or
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override, existing policy rules in the service. The `policy.d` directory is
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a place to put the YAML override files. This charm owns the
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`/etc/nova/policy.d` directory, and as such, any manual changes to it will
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be overwritten on charm upgrades.
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Policy statements are placed in a YAML file. This file (or files) is then (ZIP)
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compressed into a single file and used as an application resource. The override
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is then enabled via a Boolean charm option.
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Overrides are provided to the charm using a Juju resource called
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`policyd-override`. The resource is a ZIP file. This file, say
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`overrides.zip`, is attached to the charm by:
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Here are the essential commands (filenames are arbitrary):
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zip overrides.zip override-file.yaml
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juju attach-resource nova-cloud-controller policyd-override=overrides.zip
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The policy override is enabled in the charm using:
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juju config nova-cloud-controller use-policyd-override=true
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When `use-policyd-override` is `True` the status line of the charm will be
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prefixed with `PO:` indicating that policies have been overridden. If the
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installation of the policy override YAML files failed for any reason then the
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status line will be prefixed with `PO (broken):`. The log file for the charm
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will indicate the reason. No policy override files are installed if the `PO
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(broken):` is shown. The status line indicates that the overrides are broken,
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not that the policy for the service has failed. The policy will be the defaults
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for the charm and service.
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See appendix [Policy Overrides][cdg-appendix-n] in the [OpenStack Charms
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Deployment Guide][cdg] for a thorough treatment of this feature.
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Policy overrides on one service may affect the functionality of another
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service. Therefore, it may be necessary to provide policy overrides for
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multiple service charms to achieve a consistent set of policies across the
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OpenStack system. The charms for the other services that may need overrides
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should be checked to ensure that they support overrides before proceeding.
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# Bugs
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Please report bugs on [Launchpad][lp-bugs-charm-nova-cloud-controller].
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For general charm questions refer to the OpenStack [Charm Guide][cg].
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<!-- LINKS -->
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[cg]: https://docs.openstack.org/charm-guide
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[cdg]: https://docs.openstack.org/project-deploy-guide/charm-deployment-guide
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[cdg-appendix-n]: https://docs.openstack.org/project-deploy-guide/charm-deployment-guide/latest/app-policy-overrides.html
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[lp-bugs-charm-nova-cloud-controller]: https://bugs.launchpad.net/charm-nova-cloud-controller/+filebug
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