In designate we have a pluggable scheduler filter interface.
You can set an ordered list of filters to run on each zone create api request.
We provide a few basic filters below, and creating custom filters follows a similar pattern to schedulers.
You can create your own by extending
designate.scheduler.filters.base.Filter
and registering a new entry point in the designate.scheduler.filters
namespace like so in your setup.cfg
file:
[entry_points]
designate.scheduler.filters =
my_custom_filter = my_extension.filters.my_custom_filter:MyCustomFilter
The new filter can be added to the
scheduler_filters
list in the [service:central]
section like so:
[service:central]
scheduler_filters = attribute, pool_id_attribute, fallback, random, my_custom_filter
The filters list is ran from left to right, so if the list is set to:
[service:central]
scheduler_filters = attribute, random
There will be two filters ran,
the designate.scheduler.filters.attribute_filter.AttributeFilter
followed by designate.scheduler.filters.random_filter.RandomFilter
designate.scheduler.filters.base.
Filter
(storage)[source]¶This is the base class used for filtering Pools.
This class should implement a single public function
filter()
which accepts
a designate.objects.pool.PoolList
and returns a
designate.objects.pool.PoolList
filter
(context, pools, zone)[source]¶Filter list of supplied pools based on attributes in the request
Parameters: |
|
---|---|
Returns: |
|
designate.scheduler.filters.attribute_filter.
AttributeFilter
(storage)[source]¶Bases: designate.scheduler.filters.base.Filter
This allows users to choose the pool by supplying hints to this filter. These are provided as attributes as part of the zone object provided at zone create time.
{
"attributes": {
"pool_level": "gold",
"fast_ttl": "true",
"pops": "global",
},
"email": "user@example.com",
"name": "example.com."
}
The zone attributes are matched against the potential pool candidates, and any pools that do not match all hints are removed.
Warning
This should be uses in conjunction with the
designate.scheduler.impl_filter.filters.random_filter.RandomFilter
in case of multiple Pools matching the filters, as without it, we will
raise an error to the user.
name
= 'attribute'¶Name to enable in the [designate:central:scheduler].filters
option
list
designate.scheduler.filters.pool_id_attribute_filter.
PoolIDAttributeFilter
(storage)[source]¶Bases: designate.scheduler.filters.base.Filter
This allows users with the correct role to specify the exact pool_id to schedule the supplied zone to.
This is supplied as an attribute on the zone
{
"attributes": {
"pool_id": "794ccc2c-d751-44fe-b57f-8894c9f5c842"
},
"email": "user@example.com",
"name": "example.com."
}
The pool is loaded to ensure it exists, and then a policy check is performed to ensure the user has the correct role.
Warning
This should only be enabled if required, as it will raise a 403 Forbidden if a user without the correct role uses it.
filter
(context, pools, zone)[source]¶Attempt to load and set the pool to the one provided in the Zone attributes.
Parameters: |
|
---|---|
Returns: |
|
Raises: | Forbidden, PoolNotFound |
name
= 'pool_id_attribute'¶Name to enable in the [designate:central:scheduler].filters
option
list
designate.scheduler.filters.random_filter.
RandomFilter
(storage)[source]¶Bases: designate.scheduler.filters.base.Filter
Randomly chooses one of the input pools if there is multiple supplied.
Note
This should be used as one of the last filters, as it reduces the supplied pool list to one.
name
= 'random'¶Name to enable in the [designate:central:scheduler].filters
option
list
designate.scheduler.filters.fallback_filter.
FallbackFilter
(storage)[source]¶Bases: designate.scheduler.filters.base.Filter
If there is no zones available to schedule to, this filter will insert the default_pool_id.
Note
This should be used as one of the last filters, if you want to preserve behavior from before the scheduler existed.
name
= 'fallback'¶Name to enable in the [designate:central:scheduler].filters
option
list
designate.scheduler.filters.default_pool_filter.
DefaultPoolFilter
(storage)[source]¶Bases: designate.scheduler.filters.base.Filter
This filter will always return the default pool specified in the designate config file
Warning
This should be used as the only filter, as it will always return the
same thing - a designate.objects.pool.PoolList
with a single
designate.objects.pool.Pool
name
= 'default_pool'¶Name to enable in the [designate:central:scheduler].filters
option
list
designate.scheduler.filters.in_doubt_default_pool_filter.
InDoubtDefaultPoolFilter
(storage)[source]¶Bases: designate.scheduler.filters.base.Filter
If the previous filter(s) didn’t make a clear selection of one pool and if the default pool is in the set of multiple pools, this filter will select the default pool.
This filter will pass through the pool list, if there are one or less pools available to schedule to, or if the default pool is not in the set of multiple pools.
Note
This should be used as one of the last filters.
name
= 'in_doubt_default_pool'¶Name to enable in the [designate:central:scheduler].filters
option
list
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