[CI/Build] Pin OpenTelemetry versions and make errors clearer (#7266)

[CI/Build] Pin OpenTelemetry versions and make a availability errors clearer (#7266)

vllm/config.py

@@ -12,7 +12,7 @@ from vllm.logger import init_logger
 from vllm.model_executor.layers.quantization import QUANTIZATION_METHODS
 from vllm.model_executor.models import ModelRegistry
 from vllm.platforms import current_platform
-from vllm.tracing import is_otel_installed
+from vllm.tracing import is_otel_available, otel_import_error_traceback
 from vllm.transformers_utils.config import get_config, get_hf_text_config
 from vllm.utils import (STR_NOT_IMPL_ENC_DEC_CUDAGRAPH, GiB_bytes,
                         cuda_device_count_stateless, get_cpu_memory, is_cpu,
@@ -1721,9 +1721,11 @@ class ObservabilityConfig:
     collect_model_execute_time: bool = False
 
     def __post_init__(self):
-        if not is_otel_installed() and self.otlp_traces_endpoint is not None:
-            raise ValueError("OpenTelemetry packages must be installed before "
-                             "configuring 'otlp_traces_endpoint'")
+        if not is_otel_available() and self.otlp_traces_endpoint is not None:
+            raise ValueError(
+                "OpenTelemetry is not available. Unable to configure "
+                "'otlp_traces_endpoint'. Ensure OpenTelemetry packages are "
+                f"installed. Original error:\n{otel_import_error_traceback}")
 
         if ((self.collect_model_forward_time
              or self.collect_model_execute_time)