[Frontend] Support cache_salt in /v1/completions and /v1/responses (#20981)

Signed-off-by: Marko Rosenmueller <5467316+dr75@users.noreply.github.com>

vllm/entrypoints/openai/api_server.py

@@ -1540,6 +1540,7 @@ async def init_app_state(
         state.openai_serving_models,
         request_logger=request_logger,
         return_tokens_as_token_ids=args.return_tokens_as_token_ids,
+        enable_prompt_tokens_details=args.enable_prompt_tokens_details,
         enable_force_include_usage=args.enable_force_include_usage,
     ) if "generate" in model_config.supported_tasks else None
     state.openai_serving_pooling = OpenAIServingPooling(

vllm/entrypoints/openai/protocol.py

@@ -290,6 +290,15 @@ class ResponsesRequest(OpenAIBaseModel):
             "default: 0). Any priority other than 0 will raise an error "
             "if the served model does not use priority scheduling."),
     )
+    cache_salt: Optional[str] = Field(
+        default=None,
+        description=(
+            "If specified, the prefix cache will be salted with the provided "
+            "string to prevent an attacker to guess prompts in multi-user "
+            "environments. The salt should be random, protected from "
+            "access by 3rd parties, and long enough to be "
+            "unpredictable (e.g., 43 characters base64-encoded, corresponding "
+            "to 256 bit). Not supported by vLLM engine V0."))
     # --8<-- [end:responses-extra-params]
 
     _DEFAULT_SAMPLING_PARAMS = {
@@ -351,6 +360,19 @@ class ResponsesRequest(OpenAIBaseModel):
             raise ValueError("prompt template is not supported")
         return data
 
+    @model_validator(mode="before")
+    def check_cache_salt_support(cls, data):
+        if data.get("cache_salt") is not None:
+            if not envs.VLLM_USE_V1:
+                raise ValueError(
+                    "Parameter 'cache_salt' is not supported with "
+                    "this instance of vLLM, which uses engine V0.")
+            if not isinstance(data["cache_salt"],
+                              str) or not data["cache_salt"]:
+                raise ValueError("Parameter 'cache_salt' must be a "
+                                 "non-empty string if provided.")
+        return data
+
 
 class ChatCompletionRequest(OpenAIBaseModel):
     # Ordered by official OpenAI API documentation
@@ -1004,6 +1026,16 @@ class CompletionRequest(OpenAIBaseModel):
             " as strings of the form 'token_id:{token_id}' so that tokens "
             "that are not JSON-encodable can be identified."))
 
+    cache_salt: Optional[str] = Field(
+        default=None,
+        description=(
+            "If specified, the prefix cache will be salted with the provided "
+            "string to prevent an attacker to guess prompts in multi-user "
+            "environments. The salt should be random, protected from "
+            "access by 3rd parties, and long enough to be "
+            "unpredictable (e.g., 43 characters base64-encoded, corresponding "
+            "to 256 bit). Not supported by vLLM engine V0."))
+
     kv_transfer_params: Optional[dict[str, Any]] = Field(
         default=None,
         description="KVTransfer parameters used for disaggregated serving.")
@@ -1180,6 +1212,20 @@ class CompletionRequest(OpenAIBaseModel):
                 "At least one of `prompt` or `prompt_embeds` must be set.")
         return data
 
+    @model_validator(mode="before")
+    @classmethod
+    def check_cache_salt_support(cls, data):
+        if data.get("cache_salt") is not None:
+            if not envs.VLLM_USE_V1:
+                raise ValueError(
+                    "Parameter 'cache_salt' is not supported with "
+                    "this instance of vLLM, which uses engine V0.")
+            if not isinstance(data["cache_salt"],
+                              str) or not data["cache_salt"]:
+                raise ValueError("Parameter 'cache_salt' must be a "
+                                 "non-empty string if provided.")
+        return data
+
 
 class EmbeddingCompletionRequest(OpenAIBaseModel):
     # Ordered by official OpenAI API documentation

vllm/entrypoints/openai/serving_completion.py

@@ -23,6 +23,7 @@ from vllm.entrypoints.openai.protocol import (CompletionLogProbs,
                                               CompletionResponseStreamChoice,
                                               CompletionStreamResponse,
                                               ErrorResponse,
+                                              PromptTokenUsageInfo,
                                               RequestResponseMetadata,
                                               UsageInfo)
 from vllm.entrypoints.openai.serving_engine import (
@@ -56,6 +57,7 @@ class OpenAIServingCompletion(OpenAIServing):
         *,
         request_logger: Optional[RequestLogger],
         return_tokens_as_token_ids: bool = False,
+        enable_prompt_tokens_details: bool = False,
         enable_force_include_usage: bool = False,
     ):
         super().__init__(engine_client=engine_client,
@@ -64,6 +66,7 @@ class OpenAIServingCompletion(OpenAIServing):
                          request_logger=request_logger,
                          return_tokens_as_token_ids=return_tokens_as_token_ids,
                          enable_force_include_usage=enable_force_include_usage)
+        self.enable_prompt_tokens_details = enable_prompt_tokens_details
         self.default_sampling_params = (
             self.model_config.get_diff_sampling_param())
         if self.default_sampling_params:
@@ -313,6 +316,8 @@ class OpenAIServingCompletion(OpenAIServing):
         previous_num_tokens = [0] * num_choices * num_prompts
         has_echoed = [False] * num_choices * num_prompts
         num_prompt_tokens = [0] * num_prompts
+        num_cached_tokens = None
+        first_iteration = True
 
         stream_options = request.stream_options
         if stream_options:
@@ -328,6 +333,10 @@ class OpenAIServingCompletion(OpenAIServing):
                 prompt_token_ids = res.prompt_token_ids
                 prompt_logprobs = res.prompt_logprobs
 
+                if first_iteration:
+                    num_cached_tokens = res.num_cached_tokens
+                    first_iteration = False
+
                 if res.prompt is not None:
                     prompt_text = res.prompt
                 else:
@@ -431,6 +440,10 @@ class OpenAIServingCompletion(OpenAIServing):
                 completion_tokens=total_completion_tokens,
                 total_tokens=total_prompt_tokens + total_completion_tokens)
 
+            if self.enable_prompt_tokens_details and num_cached_tokens:
+                final_usage_info.prompt_tokens_details = PromptTokenUsageInfo(
+                    cached_tokens=num_cached_tokens)
+
             if include_usage:
                 final_usage_chunk = CompletionStreamResponse(
                     id=request_id,
@@ -535,6 +548,10 @@ class OpenAIServingCompletion(OpenAIServing):
             total_tokens=num_prompt_tokens + num_generated_tokens,
         )
 
+        if self.enable_prompt_tokens_details and final_res.num_cached_tokens:
+            usage.prompt_tokens_details = PromptTokenUsageInfo(
+                cached_tokens=final_res.num_cached_tokens)
+
         request_metadata.final_usage_info = usage
 
         return CompletionResponse(

vllm/entrypoints/openai/serving_engine.py

@@ -811,6 +811,12 @@ class OpenAIServing:
                 prompt_token_ids=request_prompt_text["prompt_token_ids"])
             for request_prompt_text in request_prompts_text
         ]
+        cache_salt = request.cache_salt if (
+            hasattr(request, "cache_salt")
+            and request.cache_salt is not None) else None
+        if cache_salt:
+            for prompt_text in engine_prompts_text:
+                prompt_text["cache_salt"] = cache_salt
 
         # This check is equivalent to simply checking if
         # `request_prompts_embeds` is empty, but it's difficult to propagate
@@ -828,6 +834,9 @@ class OpenAIServing:
                 prompt_embeds=request_prompt_embeds["prompt_embeds"])
             for request_prompt_embeds in request_prompts_embeds
         ]
+        if cache_salt:
+            for prompt_embed in engine_prompts_embeds:
+                prompt_embed["cache_salt"] = cache_salt
 
         request_prompts = request_prompts_embeds + request_prompts_text
         engine_prompts = engine_prompts_embeds + engine_prompts_text