SigLIP example add chat_template (#29902)

Signed-off-by: piood <2477084691@qq.com>

examples/pooling/embed/openai_chat_embedding_client_for_multimodal.py

@@ -150,7 +150,8 @@ def run_siglip(client: OpenAI, model: str):
     Start the server using:
 
     vllm serve google/siglip-base-patch16-224 \
-        --runner pooling
+        --runner pooling \
+        --chat-template template_basic.jinja
     """
 
     response = create_chat_embeddings(

vllm/entrypoints/chat_utils.py

@@ -1139,11 +1139,19 @@ def validate_chat_template(chat_template: Path | str | None):
             not any(c in chat_template for c in JINJA_CHARS)
             and not Path(chat_template).exists()
         ):
-            raise ValueError(
-                f"The supplied chat template string ({chat_template}) "
-                f"appears path-like, but doesn't exist!"
+            # Try to find the template in the built-in templates directory
+            from vllm.transformers_utils.chat_templates.registry import (
+                CHAT_TEMPLATES_DIR,
             )
 
+            builtin_template_path = CHAT_TEMPLATES_DIR / chat_template
+            if not builtin_template_path.exists():
+                raise ValueError(
+                    f"The supplied chat template string ({chat_template}) "
+                    f"appears path-like, but doesn't exist! "
+                    f"Tried: {chat_template} and {builtin_template_path}"
+                )
+
     else:
         raise TypeError(f"{type(chat_template)} is not a valid chat template type")
 
@@ -1173,12 +1181,23 @@ def _load_chat_template(
 
         JINJA_CHARS = "{}\n"
         if not any(c in chat_template for c in JINJA_CHARS):
-            msg = (
-                f"The supplied chat template ({chat_template}) "
-                f"looks like a file path, but it failed to be "
-                f"opened. Reason: {e}"
+            # Try to load from the built-in templates directory
+            from vllm.transformers_utils.chat_templates.registry import (
+                CHAT_TEMPLATES_DIR,
             )
-            raise ValueError(msg) from e
+
+            builtin_template_path = CHAT_TEMPLATES_DIR / chat_template
+            try:
+                with open(builtin_template_path) as f:
+                    return f.read()
+            except OSError:
+                msg = (
+                    f"The supplied chat template ({chat_template}) "
+                    f"looks like a file path, but it failed to be opened. "
+                    f"Tried: {chat_template} and {builtin_template_path}. "
+                    f"Reason: {e}"
+                )
+                raise ValueError(msg) from e
 
         # If opening a file fails, set chat template to be args to
         # ensure we decode so our escape are interpreted correctly