Predicates

A predicate is a condition on the incoming request. A route carries a list of them and takes the request only when every one of them accepts it: predicates are ANDed, never ORed. A route with no predicate at all takes everything.

To express an OR, write two routes - or use a predicate that already accepts a list. Several patterns, hosts, methods or values inside one predicate act as OR.

routes:
  - id: orders
    name: Orders API
    enabled: true
    order: 100
    upstream: http://orders.internal:8080
    predicates:
      - type: path
        args:
          patterns:
            - /orders/**
      - type: method
        args:
          methods:
            - GET
            - POST

That route answers a GET or a POST under /orders, and nothing else.

Which route answers

Routes are tried in ascending order (ties broken by name) and the first route whose predicates all match answers. Nothing matched at all is a plain 404.

A route's access rule takes part in the choice: a caller the rule turns away falls through to the next route that matches, and is refused by the first route that turned them away only if no other one answers. A rule set to deny is the exception - a closed door stays closed.

A disabled route is not loaded, so it never matches.

The catch-all

A catch-all is not a setting: it is an ordinary route whose path predicate is /**, ordered last. It catches what no other route claimed, which is how an installation answers something better than a bare 404.

Trying it before shipping

The console's route tester composes a fictitious request (method, path, host, header, cookie, query, client address, clock) and shows each predicate's verdict, one line per predicate, rather than a single yes or no. The clock is part of it, so a time-window can be tried on a date that has not arrived yet.

The eleven predicates

Anything a route does to the request once it has matched is a filter.