Add documentation for resolver LB cfg

agent/structs/config_entry_discoverychain.go

@@ -1028,10 +1028,10 @@ func (l LoadBalancer) IsHashBased() bool {
 
 // RingHashConfig contains configuration for the "ring_hash" policy type
 type RingHashConfig struct {
-	// MinimumRingSize determines the minimum number of hashes per destination host
+	// MinimumRingSize determines the minimum number of entries in the hash ring
 	MinimumRingSize uint64 `json:",omitempty" alias:"minimum_ring_size"`
 
-	// MaximumRingSize determines the maximum number of hashes per destination host
+	// MaximumRingSize determines the maximum number of entries in the hash ring
 	MaximumRingSize uint64 `json:",omitempty" alias:"maximum_ring_size"`
 }
 
@@ -1058,7 +1058,7 @@ type HashPolicy struct {
 	FieldMatchValue string `json:",omitempty" alias:"field_value"`
 
 	// SourceAddress determines whether the hash should be of the source IP rather than of a field and field value.
-	// Cannot be specified along with Field and FieldMatchValue.
+	// Cannot be specified along with Field or FieldMatchValue.
 	SourceAddress bool `json:",omitempty" alias:"source_address"`
 
 	// Terminal will short circuit the computation of the hash when multiple hash policies are present.

api/config_entry_discoverychain.go

@@ -228,10 +228,10 @@ type LoadBalancer struct {
 
 // RingHashConfig contains configuration for the "ring_hash" policy type
 type RingHashConfig struct {
-	// MinimumRingSize determines the minimum number of hashes per destination host
+	// MinimumRingSize determines the minimum number of entries in the hash ring
 	MinimumRingSize uint64 `json:",omitempty" alias:"minimum_ring_size"`
 
-	// MaximumRingSize determines the maximum number of hashes per destination host
+	// MaximumRingSize determines the maximum number of entries in the hash ring
 	MaximumRingSize uint64 `json:",omitempty" alias:"maximum_ring_size"`
 }
 

website/pages/docs/agent/config-entries/service-resolver.mdx

@@ -72,6 +72,23 @@ Kind = "service-resolver"
 Name = "web"
 ```
 
+Apply consistent load balancing for requests based on `x-user-id` header:
+
+```hcl
+Kind = "service-resolver"
+Name = "web"
+
+LoadBalancer = {
+  Policy = "maglev"
+  HashPolicies = [
+    {
+      Field = "header"
+      FieldMatchValue = "x-user-id"
+    }
+  ]
+}
+```
+
 ## Available Fields
 
 - `Kind` - Must be set to `service-resolver`
@@ -117,8 +134,8 @@ Name = "web"
     resolve instead of one defined as that service's DefaultSubset If empty the
     default subset is used.
 
-        If this is specified at least one of Service, Datacenter, or Namespace
-        should be configured.
+    If this is specified at least one of Service, Datacenter, or Namespace
+    should be configured.
 
   - `Namespace` `(string: "")` - The namespace to resolve the service from
     instead of the current one.
@@ -149,6 +166,53 @@ Name = "web"
 
   - `Datacenters` `(array<string>)` - A fixed list of datacenters to try during
     failover.
+    
+- `LoadBalancer` `(LoadBalancer`) - Determines the load balancing policy and 
+   configuration for services issuing requests to this upstream.
+   This option is available in Consul versions 1.8.4 and newer.
+   
+   **Note:** The options below are specific to Envoy proxy.
+   
+  - `Policy` `(string: "")` - The load balancing policy used to select a host.
+    One of: `random`, `round_robin`, `least_request`, `ring_hash`, `maglev`.
+  
+  - `RingHashConfig` `(RingHashConfig)` - Configuration for the `ring_hash`
+    policy type.
+    
+    - `MinimumRingRize` `(int: 1024)` - Determines the minimum number of entries
+       in the hash ring.
+    
+    - `MaximumRingRize` `(int: 8192)` - Determines the maximum number of entries
+       in the hash ring.
+
+  - `LeastRequestConfig` `(LeastRequestConfig)` - Configuration for the `least_request`
+     policy type.
+    
+    - `ChoiceCount` `(int: 2)` - Determines the number of random healthy hosts
+       from which to select the one with the least requests.
+
+  - `HashPolicies` `(array<HashPolicies>)` - a list of hash policies to use for
+     hashing load balancing algorithms. Hash policies are evaluated individually
+     and combined such that identical lists result in the same hash.
+     If no hash policies are present, or none are successfully evaluated,
+     then a random backend host will be selected.
+    
+     - `Field` `(string: "")` - The attribute type to hash on.
+        Must be one of `header`,`cookie`, or `query_parameter`.
+        Cannot be specified along with `SourceAddress`.
+        
+     - `FieldMatchValue` `(string: "")` - The value to hash. 
+        ie. header name, cookie name, URL query parameter name.
+        Cannot be specified along with `SourceAddress`.
+        
+     - `SourceAddress` `(bool: false)` - Determines whether the hash should be of the source IP
+        address rather than of a field and field value.
+        Cannot be specified along with `Field` or `FieldMatchValue`.
+        
+     - `Terminal` `(bool: false)` - Will short circuit the computation of the hash
+        when multiple hash policies are present. If a hash is computed when a
+        Terminal policy is evaluated, then that hash will be used and subsequent
+        hash policies will be ignored.
 
 ## Service Subsets