doc: add doc for infernecemodelrewrites.

crd-ref-docs.yaml

@@ -4,7 +4,7 @@
 
 processor:
   ignoreTypes:
-    - "(InferencePool|InferenceObjective|InferencePoolImport)List$"
+    - "(InferencePool|InferenceObjective|InferencePoolImport|InferenceModelRewrite)List$"
   # RE2 regular expressions describing type fields that should be excluded from the generated documentation.
   ignoreFields:
     - "TypeMeta$"

mkdocs.yml

@@ -98,6 +98,7 @@ nav:
       - InferencePool: api-types/inferencepool.md
       - InferenceObjective: api-types/inferenceobjective.md
       - InferencePoolImport: api-types/inferencepoolimport.md
+      - InferenceModelRewrite: api-types/inferencemodelrewrite.md
   - Enhancements:
     - Overview: enhancements/overview.md
   - Contributing:

site-src/api-types/inferencemodelrewrite.md

@@ -0,0 +1,95 @@
+# Inference Model Rewrite
+
+??? example "Alpha since v1.2.1"
+
+    The `InferenceModelRewrite` resource is alpha and may have breaking changes in
+    future releases of the API.
+
+## Background
+
+The **InferenceModelRewrite** resource allows platform administrators and model owners to control how inference requests are routed to specific models within an Inference Pool.
+This capability is essential for managing model lifecycles without disrupting client applications.
+
+## Usages
+
+*   **Model Aliasing**: Map a model name in the request body (e.g., `food-review`) to a specific version (e.g., `food-review-v1`).
+*   **Generic Fallbacks**: Redirect unknown model requests to a default model.
+*   **Traffic Splitting**: Gradually roll out new model versions (Canary deployment) by splitting traffic between two models based on percentage weights.
+
+## Spec
+
+The full spec of the InferenceModelRewrite is defined [here](/reference/x-v1a2-spec/#inferencemodelrewrite).
+
+## Usage Examples
+
+### Model Aliasing
+
+Map a virtual model name (e.g., `food-review`) to a specific backend model version (e.g., `food-review-v1`).
+
+```yaml
+apiVersion: inference.networking.x-k8s.io/v1alpha2
+kind: InferenceModelRewrite
+metadata:
+  name: food-review-alias
+spec:
+  poolRef:
+    group: inference.networking.k8s.io
+    name: vllm-llama3-8b-instruct
+  rules:
+    - matches:
+        - model:
+            type: Exact
+            value: food-review
+      targets:
+        - modelRewrite: "food-review-v1"
+```
+
+### Generic (Wildcard) Rewrites
+
+Redirect any request with an unrecognized or unspecified model name to a default safe model. An empty `matches` list implies that the rule applies to **all** requests not matched by previous rules.
+
+```yaml
+apiVersion: inference.networking.k8s.io/v1alpha2
+kind: InferenceModelRewrite
+metadata:
+  name: generic-fallback
+spec:
+  poolRef:
+    group: inference.networking.k8s.io
+    name: vllm-llama3-8b-instruct
+  rules:
+    - matches: [] # Empty means this rule matches everything
+      targets: 
+        - modelRewrite: "meta-llama/Llama-3.1-8B-Instruct"
+```
+
+### Traffic Splitting (Canary Rollout)
+
+Divide incoming traffic for a single model name across multiple backend models. This is useful for A/B testing or gradual rollouts.
+
+```yaml
+apiVersion: inference.networking.k8s.io/v1alpha2
+kind: InferenceModelRewrite
+metadata:
+  name: food-review-canary
+spec:
+  poolRef:
+    group: inference.networking.k8s.io
+    name: vllm-llama3-8b-instruct
+  rules:
+    - matches:
+        - model:
+            type: Exact
+            value: food-review
+      targets:
+        - modelRewrite: "food-review-v1"
+          weight: 90
+        - modelRewrite: "food-review-v2"
+          weight: 10
+```
+
+## Limitations
+
+1.  **Status Reporting**: Currently, `InferenceModelRewrite` is simply a config read-only CR. It does not report status conditions (e.g., Valid or Ready) in the CRD status field.
+2.  **Scheduler Assumptions**: Traffic splitting occurs before the scheduling algorithm. The system assumes that all model servers within the referenced `InferencePool` are capable of serving the target models. If a model is missing from a specific server in the pool, requests routed to it may fail.
+3.  **Splitting algorithm**: The current traffic split is weighted-random.