feat: opentelemetry and prometheus

[zzzming]

This PR introduces as the first phase of OpenTelemetry implementation.

• Opentelemetry in the existing TelemetryService
• Optionally Prometheus can be enabled
• Prometheus port is configured. The default is 9090.
• Metrics collected by OpenTelemetry can be exposed through Prometheus
• A FastAPI middleware that collects all http related metrics

What's not implemented in this PR

• Other exporters such as Console, Jaeger, Zipkin, or any other customer exporters.

An example of prometheus scraping

$curl localhost:9090/metrics
# HELP python_gc_objects_collected_total Objects collected during gc
# TYPE python_gc_objects_collected_total counter
python_gc_objects_collected_total{generation="0"} 59153.0
python_gc_objects_collected_total{generation="1"} 31939.0
python_gc_objects_collected_total{generation="2"} 4232.0
# HELP python_gc_objects_uncollectable_total Uncollectable objects found during GC
# TYPE python_gc_objects_uncollectable_total counter
python_gc_objects_uncollectable_total{generation="0"} 0.0
python_gc_objects_uncollectable_total{generation="1"} 0.0
python_gc_objects_uncollectable_total{generation="2"} 0.0
# HELP python_gc_collections_total Number of times this generation was collected
# TYPE python_gc_collections_total counter
python_gc_collections_total{generation="0"} 1881.0
python_gc_collections_total{generation="1"} 171.0
python_gc_collections_total{generation="2"} 10.0
# HELP python_info Python platform information
# TYPE python_info gauge
python_info{implementation="CPython",major="3",minor="11",patchlevel="9",version="3.11.9"} 1.0
# HELP target_info Target metadata
# TYPE target_info gauge
target_info{service_name="langflow",telemetry_sdk_language="python",telemetry_sdk_name="opentelemetry",telemetry_sdk_version="1.25.0"} 1.0
# HELP requests_bytes_total The number of requests
# TYPE requests_bytes_total counter
requests_bytes_total 1.0
# HELP http_server_active_requests measures the number of concurrent HTTP requests that are currently in-flight
# TYPE http_server_active_requests gauge
http_server_active_requests{http_flavor="1.1",http_host="127.0.0.1:7860",http_method="GET",http_scheme="http",http_server_name="localhost:7860"} 0.0
# HELP http_server_duration_milliseconds Duration of HTTP client requests.
# TYPE http_server_duration_milliseconds histogram
http_server_duration_milliseconds_bucket{http_flavor="1.1",http_host="127.0.0.1:7860",http_method="GET",http_scheme="http",http_server_name="localhost:7860",http_target="/health_check",le="0.0",net_host_port="7860"} 0.0
http_server_duration_milliseconds_bucket{http_flavor="1.1",http_host="127.0.0.1:7860",http_method="GET",http_scheme="http",http_server_name="localhost:7860",http_target="/health_check",le="5.0",net_host_port="7860"} 0.0
http_server_duration_milliseconds_bucket{http_flavor="1.1",http_host="127.0.0.1:7860",http_method="GET",http_scheme="http",http_server_name="localhost:7860",http_target="/health_check",le="10.0",net_host_port="7860"} 0.0
http_server_duration_milliseconds_bucket{http_flavor="1.1",http_host="127.0.0.1:7860",http_method="GET",http_scheme="http",http_server_name="localhost:7860",http_target="/health_check",le="25.0",net_host_port="7860"} 1.0
http_server_duration_milliseconds_bucket{http_flavor="1.1",http_host="127.0.0.1:7860",http_method="GET",http_scheme="http",http_server_name="localhost:7860",http_target="/health_check",le="50.0",net_host_port="7860"} 2.0
http_server_duration_milliseconds_bucket{http_flavor="1.1",http_host="127.0.0.1:7860",http_method="GET",http_scheme="http",http_server_name="localhost:7860",http_target="/health_check",le="75.0",net_host_port="7860"} 2.0
http_server_duration_milliseconds_bucket{http_flavor="1.1",http_host="127.0.0.1:7860",http_method="GET",http_scheme="http",http_server_name="localhost:7860",http_target="/health_check",le="100.0",net_host_port="7860"} 2.0
http_server_duration_milliseconds_bucket{http_flavor="1.1",http_host="127.0.0.1:7860",http_method="GET",http_scheme="http",http_server_name="localhost:7860",http_target="/health_check",le="250.0",net_host_port="7860"} 2.0
http_server_duration_milliseconds_bucket{http_flavor="1.1",http_host="127.0.0.1:7860",http_method="GET",http_scheme="http",http_server_name="localhost:7860",http_target="/health_check",le="500.0",net_host_port="7860"} 2.0
http_server_duration_milliseconds_bucket{http_flavor="1.1",http_host="127.0.0.1:7860",http_method="GET",http_scheme="http",http_server_name="localhost:7860",http_target="/health_check",le="750.0",net_host_port="7860"} 2.0
http_server_duration_milliseconds_bucket{http_flavor="1.1",http_host="127.0.0.1:7860",http_method="GET",http_scheme="http",http_server_name="localhost:7860",http_target="/health_check",le="1000.0",net_host_port="7860"} 2.0
http_server_duration_milliseconds_bucket{http_flavor="1.1",http_host="127.0.0.1:7860",http_method="GET",http_scheme="http",http_server_name="localhost:7860",http_target="/health_check",le="2500.0",net_host_port="7860"} 2.0
http_server_duration_milliseconds_bucket{http_flavor="1.1",http_host="127.0.0.1:7860",http_method="GET",http_scheme="http",http_server_name="localhost:7860",http_target="/health_check",le="5000.0",net_host_port="7860"} 2.0
http_server_duration_milliseconds_bucket{http_flavor="1.1",http_host="127.0.0.1:7860",http_method="GET",http_scheme="http",http_server_name="localhost:7860",http_target="/health_check",le="7500.0",net_host_port="7860"} 2.0
http_server_duration_milliseconds_bucket{http_flavor="1.1",http_host="127.0.0.1:7860",http_method="GET",http_scheme="http",http_server_name="localhost:7860",http_target="/health_check",le="10000.0",net_host_port="7860"} 2.0
http_server_duration_milliseconds_bucket{http_flavor="1.1",http_host="127.0.0.1:7860",http_method="GET",http_scheme="http",http_server_name="localhost:7860",http_target="/health_check",le="+Inf",net_host_port="7860"} 2.0
http_server_duration_milliseconds_count{http_flavor="1.1",http_host="127.0.0.1:7860",http_method="GET",http_scheme="http",http_server_name="localhost:7860",http_target="/health_check",net_host_port="7860"} 2.0
http_server_duration_milliseconds_sum{http_flavor="1.1",http_host="127.0.0.1:7860",http_method="GET",http_scheme="http",http_server_name="localhost:7860",http_target="/health_check",net_host_port="7860"} 52.0
# HELP http_server_response_size_bytes measures the size of HTTP response messages (compressed).
# TYPE http_server_response_size_bytes histogram
http_server_response_size_bytes_bucket{http_flavor="1.1",http_host="127.0.0.1:7860",http_method="GET",http_scheme="http",http_server_name="localhost:7860",http_target="/health_check",le="0.0",net_host_port="7860"} 0.0
http_server_response_size_bytes_bucket{http_flavor="1.1",http_host="127.0.0.1:7860",http_method="GET",http_scheme="http",http_server_name="localhost:7860",http_target="/health_check",le="5.0",net_host_port="7860"} 0.0
http_server_response_size_bytes_bucket{http_flavor="1.1",http_host="127.0.0.1:7860",http_method="GET",http_scheme="http",http_server_name="localhost:7860",http_target="/health_check",le="10.0",net_host_port="7860"} 0.0
http_server_response_size_bytes_bucket{http_flavor="1.1",http_host="127.0.0.1:7860",http_method="GET",http_scheme="http",http_server_name="localhost:7860",http_target="/health_check",le="25.0",net_host_port="7860"} 0.0
http_server_response_size_bytes_bucket{http_flavor="1.1",http_host="127.0.0.1:7860",http_method="GET",http_scheme="http",http_server_name="localhost:7860",http_target="/health_check",le="50.0",net_host_port="7860"} 0.0
http_server_response_size_bytes_bucket{http_flavor="1.1",http_host="127.0.0.1:7860",http_method="GET",http_scheme="http",http_server_name="localhost:7860",http_target="/health_check",le="75.0",net_host_port="7860"} 2.0
http_server_response_size_bytes_bucket{http_flavor="1.1",http_host="127.0.0.1:7860",http_method="GET",http_scheme="http",http_server_name="localhost:7860",http_target="/health_check",le="100.0",net_host_port="7860"} 2.0
http_server_response_size_bytes_bucket{http_flavor="1.1",http_host="127.0.0.1:7860",http_method="GET",http_scheme="http",http_server_name="localhost:7860",http_target="/health_check",le="250.0",net_host_port="7860"} 2.0
http_server_response_size_bytes_bucket{http_flavor="1.1",http_host="127.0.0.1:7860",http_method="GET",http_scheme="http",http_server_name="localhost:7860",http_target="/health_check",le="500.0",net_host_port="7860"} 2.0
http_server_response_size_bytes_bucket{http_flavor="1.1",http_host="127.0.0.1:7860",http_method="GET",http_scheme="http",http_server_name="localhost:7860",http_target="/health_check",le="750.0",net_host_port="7860"} 2.0
http_server_response_size_bytes_bucket{http_flavor="1.1",http_host="127.0.0.1:7860",http_method="GET",http_scheme="http",http_server_name="localhost:7860",http_target="/health_check",le="1000.0",net_host_port="7860"} 2.0
http_server_response_size_bytes_bucket{http_flavor="1.1",http_host="127.0.0.1:7860",http_method="GET",http_scheme="http",http_server_name="localhost:7860",http_target="/health_check",le="2500.0",net_host_port="7860"} 2.0
http_server_response_size_bytes_bucket{http_flavor="1.1",http_host="127.0.0.1:7860",http_method="GET",http_scheme="http",http_server_name="localhost:7860",http_target="/health_check",le="5000.0",net_host_port="7860"} 2.0
http_server_response_size_bytes_bucket{http_flavor="1.1",http_host="127.0.0.1:7860",http_method="GET",http_scheme="http",http_server_name="localhost:7860",http_target="/health_check",le="7500.0",net_host_port="7860"} 2.0
http_server_response_size_bytes_bucket{http_flavor="1.1",http_host="127.0.0.1:7860",http_method="GET",http_scheme="http",http_server_name="localhost:7860",http_target="/health_check",le="10000.0",net_host_port="7860"} 2.0
http_server_response_size_bytes_bucket{http_flavor="1.1",http_host="127.0.0.1:7860",http_method="GET",http_scheme="http",http_server_name="localhost:7860",http_target="/health_check",le="+Inf",net_host_port="7860"} 2.0
http_server_response_size_bytes_count{http_flavor="1.1",http_host="127.0.0.1:7860",http_method="GET",http_scheme="http",http_server_name="localhost:7860",http_target="/health_check",net_host_port="7860"} 2.0
http_server_response_size_bytes_sum{http_flavor="1.1",http_host="127.0.0.1:7860",http_method="GET",http_scheme="http",http_server_name="localhost:7860",http_target="/health_check",net_host_port="7860"} 136.0

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_{Last Modified at 04 Jul 24 21:19 UTC}

[ogabrielluiz]

This is awesome. Thanks, @zzzming

LGTM