Add table-style rate-limiting capability (#15)

* add tableActions to proto
* add descriptor rules stuff to proto, change 'table' to 'set'
* Merge branch 'master' of https://github.com/solo-io/solo-apis into table-rate-limiting
* make generate-code
* run ci/check-code-gen.sh

api/rate-limiter/v1alpha1/ratelimit.proto

@@ -26,6 +26,9 @@ message RateLimitConfigSpec {
     // Actions specify how the client (Envoy) will compose the descriptors that
     // will be sent to the server to make a rate limiting decision.
     repeated RateLimitActions rate_limits = 2;
+
+    // The set descriptors that will be applied to the server.
+    repeated SetDescriptor set_descriptors = 3;
   }
 
   // Each `RateLimitConfig` is an instance of one specific configuration type.
@@ -63,7 +66,7 @@ message RateLimitConfigStatus {
 // Each configuration contains a top level descriptor list and potentially multiple nested lists beneath that.
 // The format is:
 //
-// ```yaml
+// ```
 // descriptors:
 //   - key: <rule key: required>
 //     value: <rule value: optional>
@@ -80,7 +83,7 @@ message RateLimitConfigStatus {
 // Otherwise, nested descriptors allow more complex matching and rate limiting scenarios.
 message Descriptor {
 
-  // The key of the descriptor. Ths field is required.
+  // The key of the descriptor. This field is required.
   string key = 1;
 
   // Optional value for the descriptor. If omitted, the server will create a rate limit for
@@ -115,9 +118,80 @@ message Descriptor {
   bool always_apply = 6;
 }
 
-// Each action in the list maps part of the request (or its context) to a descriptor. The tuple of descriptors
+// A setDescriptor is a list of key/value pairs that the rate limit server uses to select
+// the correct rate limit to use when limiting with the set style. Descriptors are case-sensitive.
+//
+// Each configuration contains a simpleDescriptor list and a rateLimit.
+// The format is:
+//
+// ```
+// set_descriptors:
+//  - simple_descriptors: (optional block)
+//      - key: <rule key: required>
+//        value: <rule value: optional>
+//      - ... (repetition of above)
+//    rate_limit:
+//      requests_per_unit: <see below: required>
+//      unit: <see below: required>
+//    always_apply: <bool value: optional>
+//  - ... (repetition of above)
+// ```
+//
+// Each SetDescriptor defines a new Rate Limit "rule". When a request comes in, rate limit
+// actions are applied to the request to generate descriptor tuples that are sent to the rate limit
+// server. If any rule is triggered then the entire request returns HTTP 429 Too Many Requests.
+//
+// The `rate_limit` block sets up an actual rate limit rule.
+message SetDescriptor {
+
+  // Simple descriptor key/value pairs.
+  repeated SimpleDescriptor simple_descriptors = 1;
+
+  // Rate limit rule for the descriptor.
+  RateLimit rate_limit = 2;
+
+  // Typically, rule priority is signalled by rule ordering, as the first rule match for
+  // the descriptor tuple generated by the rate limit actions is used.
+  //
+  // In some cases this is too restrictive; A boolean override can be specified. Any rule with `alwaysApply` set to `true` will
+  // always be considered for rate limiting, regardless of the rule's place in the ordered list of rules.
+  // The first rule to match will still be considered. (This can be a rule that also has `alwaysApply` set to `true`.)
+  //
+  // If any of these rules trigger rate limiting then the entire request will return a 429.
+  // Rules that are not considered for rate limiting are ignored in the
+  // rate limit server, and their request count is not incremented in the rate limit server cache.
+  //
+  // Defaults to false.
+  bool always_apply = 3;
+}
+
+// A simpleDescriptor is a list of key/value pairs that the rate limit server uses to select
+// the correct rate limit to use when limiting with the set style. Descriptors are case-sensitive.
+//
+// The format is:
+//
+// ```
+//  simple_descriptors:
+//    - key: <rule key: required>
+//      value: <rule value: optional>
+//    - ... (repetition of above)
+// ```
+//
+// Each simpleDescriptor in a simpleDescriptor list must have a key. It can also optionally have a value to enable
+// a more specific match.
+message SimpleDescriptor {
+
+  // The key of the descriptor. This field is required.
+  string key = 1;
+
+  // Optional value for the descriptor. If omitted, the server will create a rate limit for
+  // each value that is provided for this descriptor in rate limit requests.
+  string value = 2;
+}
+
+// Each action and setAction in the lists maps part of the request (or its context) to a descriptor. The tuple or set of descriptors
 // generated by the provided actions is sent to the rate limit server and matched against rate limit rules.
-// Order matters on the provided actions, e.g. the following actions:
+// Order matters on provided actions but not on setActions, e.g. the following actions:
 // - actions:
 //   - requestHeaders:
 //      descriptorKey: account_id
@@ -142,8 +216,30 @@ message Descriptor {
 //    rateLimit:
 //      requestsPerUnit: 20
 //      unit: MINUTE
+//
+// Similarly, the following setActions:
+// - setActions:
+//   - requestHeaders:
+//      descriptorKey: account_id
+//      headerName: x-account-id
+//   - requestHeaders:
+//      descriptorKey: plan
+//      headerName: x-plan
+// define an unordered descriptor set like so: {('account_id', '<x-account-id value>'), ('plan', '<x-plan value>')}
+//
+// This set would match the following setDescriptor:
+//
+// setDescriptors:
+// - simpleDescriptors:
+//   - key: plan
+//     value: BASIC
+//   - key: account_id
+//  rateLimit:
+//    requestsPerUnit: 20
+//    unit: MINUTE
 message RateLimitActions {
   repeated Action actions = 1;
+  repeated Action set_actions = 2;
 }
 
 // A `RateLimit` specifies the actual rate limit that will be used when there is a match.