If multiple AttributeGene configurations produce the same attribute, the
result of the last configuration will be visible to downstream filters.
AttributeGeneration define generation of one attribute.
The name of the attribute that is populated on a successful match.
An attribute name SHOULD NOT contain a .. You may use underscores for
istio_ attribute namespace is reserved by Istio.
AttributeGeneration may fail to evaluate when an attribute is not
available. For example, response.code may not be available when a request
ends abruptly. When attribute generation fails, it will not populate the
If the generated attribute is used by an authz plugin, it should account
for the possibility that the attribute may be missing. Use
has(attribute_name) function to check for presence of an attribute before
using its value, and provide appropriate defaults. For example the
following is a safe use of response.code