For filters that need to act on a per-route basis, it would be useful to support a per-route configuration mechanism. This config would be opaque to the envoy server itself but accessible to filters through an 'options' array of key-value pairs defined on route:

For example:

{
"prefix": "/my/route",
"cluster": "mycluster",
"options": [
"my_filter_specific_confing": "some value"
]
}