[MISC] Make vllm version configurable (#651)

Sometimes, user install a dev/editable version of vllm. In this case, we
should make sure vllm-ascend works as well.

This PR add a new env `VLLM_VERSION`. It's used for developers who edit
vllm. In this case, developers should set thie env to make sure which
vllm version is installed and used.

Signed-off-by: wangxiyuan <wangxiyuan1007@gmail.com>

vllm_ascend/utils.py

@@ -18,7 +18,7 @@
 #
 import torch
 import torch_npu  # noqa: F401
-from packaging.version import Version
+from packaging.version import InvalidVersion, Version
 from vllm.logger import logger
 
 import vllm_ascend.envs as envs
@@ -86,6 +86,17 @@ def adapt_patch(is_global_patch: bool = False):
         from vllm_ascend.patch import worker  # noqa: F401
 
 
-def vllm_version_is(version: str):
-    import vllm
-    return Version(vllm.__version__) == Version(version)
+def vllm_version_is(target_vllm_version: str):
+    if envs.VLLM_VERSION is not None:
+        vllm_version = envs.VLLM_VERSION
+    else:
+        import vllm
+        vllm_version = vllm.__version__
+    try:
+        return Version(vllm_version) == Version(target_vllm_version)
+    except InvalidVersion:
+        raise ValueError(
+            f"Invalid vllm version {vllm_version} found. A dev version of vllm "
+            "is installed probably. Set the environment variable VLLM_VERSION "
+            "to control it by hand. And please make sure the vaule follows the "
+            "format of x.y.z.")