feat: instrument HTTP protocol detection metrics

[olix0r]

This change updates the DetectHttp middleware to record metrics about HTTP
protocol detection. Specfically, it records the the counts of results and a very
coarse histogram of the time taken to detect the protocol.

The inbound, outbound, and admin (via inbound) stacks are updated to record
metrics against the main registry.

Example metrics

# HELP inbound_tcp_detect_http_duration_seconds Time taken for protocol detection.
# TYPE inbound_tcp_detect_http_duration_seconds histogram
# UNIT inbound_tcp_detect_http_duration_seconds seconds
inbound_tcp_detect_http_duration_seconds_sum{srv_group="",srv_kind="default",srv_name="all-unauthenticated",srv_port="4191"} 0.0019456109999999997
inbound_tcp_detect_http_duration_seconds_count{srv_group="",srv_kind="default",srv_name="all-unauthenticated",srv_port="4191"} 52
inbound_tcp_detect_http_duration_seconds_bucket{le="0.001",srv_group="",srv_kind="default",srv_name="all-unauthenticated",srv_port="4191"} 52
inbound_tcp_detect_http_duration_seconds_bucket{le="0.1",srv_group="",srv_kind="default",srv_name="all-unauthenticated",srv_port="4191"} 52
inbound_tcp_detect_http_duration_seconds_bucket{le="+Inf",srv_group="",srv_kind="default",srv_name="all-unauthenticated",srv_port="4191"} 52

# HELP inbound_tcp_detect_http_results Protocol detection results.
# TYPE inbound_tcp_detect_http_results counter
inbound_tcp_detect_http_results_total{result="read_timeout",srv_group="",srv_kind="default",srv_name="all-unauthenticated",srv_port="4191"} 0
inbound_tcp_detect_http_results_total{result="not_http",srv_group="",srv_kind="default",srv_name="all-unauthenticated",srv_port="4191"} 0
inbound_tcp_detect_http_results_total{result="http/1",srv_group="",srv_kind="default",srv_name="all-unauthenticated",srv_port="4191"} 52
inbound_tcp_detect_http_results_total{result="h2",srv_group="",srv_kind="default",srv_name="all-unauthenticated",srv_port="4191"} 0
inbound_tcp_detect_http_results_total{result="error",srv_group="",srv_kind="default",srv_name="all-unauthenticated",srv_port="4191"} 0

# HELP outbound_tcp_detect_http_duration_seconds Time taken for protocol detection.
# TYPE outbound_tcp_detect_http_duration_seconds histogram
# UNIT outbound_tcp_detect_http_duration_seconds seconds
outbound_tcp_detect_http_duration_seconds_sum{parent_group="core",parent_kind="Service",parent_namespace="emojivoto",parent_name="voting-svc",parent_port="8080",parent_section_name=""} 0.000010969
outbound_tcp_detect_http_duration_seconds_count{parent_group="core",parent_kind="Service",parent_namespace="emojivoto",parent_name="voting-svc",parent_port="8080",parent_section_name=""} 1
outbound_tcp_detect_http_duration_seconds_bucket{le="0.001",parent_group="core",parent_kind="Service",parent_namespace="emojivoto",parent_name="voting-svc",parent_port="8080",parent_section_name=""} 1
outbound_tcp_detect_http_duration_seconds_bucket{le="0.1",parent_group="core",parent_kind="Service",parent_namespace="emojivoto",parent_name="voting-svc",parent_port="8080",parent_section_name=""} 1
outbound_tcp_detect_http_duration_seconds_bucket{le="+Inf",parent_group="core",parent_kind="Service",parent_namespace="emojivoto",parent_name="voting-svc",parent_port="8080",parent_section_name=""} 1
outbound_tcp_detect_http_duration_seconds_sum{parent_group="core",parent_kind="Service",parent_namespace="emojivoto",parent_name="emoji-svc",parent_port="8080",parent_section_name=""} 0.000008034
outbound_tcp_detect_http_duration_seconds_count{parent_group="core",parent_kind="Service",parent_namespace="emojivoto",parent_name="emoji-svc",parent_port="8080",parent_section_name=""} 1
outbound_tcp_detect_http_duration_seconds_bucket{le="0.001",parent_group="core",parent_kind="Service",parent_namespace="emojivoto",parent_name="emoji-svc",parent_port="8080",parent_section_name=""} 1
outbound_tcp_detect_http_duration_seconds_bucket{le="0.1",parent_group="core",parent_kind="Service",parent_namespace="emojivoto",parent_name="emoji-svc",parent_port="8080",parent_section_name=""} 1
outbound_tcp_detect_http_duration_seconds_bucket{le="+Inf",parent_group="core",parent_kind="Service",parent_namespace="emojivoto",parent_name="emoji-svc",parent_port="8080",parent_section_name=""} 1

# HELP outbound_tcp_detect_http_results Protocol detection results.
# TYPE outbound_tcp_detect_http_results counter
outbound_tcp_detect_http_results_total{result="http/1",parent_group="core",parent_kind="Service",parent_namespace="emojivoto",parent_name="voting-svc",parent_port="8080",parent_section_name=""} 0
outbound_tcp_detect_http_results_total{result="not_http",parent_group="core",parent_kind="Service",parent_namespace="emojivoto",parent_name="voting-svc",parent_port="8080",parent_section_name=""} 0
outbound_tcp_detect_http_results_total{result="not_http",parent_group="core",parent_kind="Service",parent_namespace="emojivoto",parent_name="emoji-svc",parent_port="8080",parent_section_name=""} 0
outbound_tcp_detect_http_results_total{result="read_timeout",parent_group="core",parent_kind="Service",parent_namespace="emojivoto",parent_name="voting-svc",parent_port="8080",parent_section_name=""} 0
outbound_tcp_detect_http_results_total{result="h2",parent_group="core",parent_kind="Service",parent_namespace="emojivoto",parent_name="voting-svc",parent_port="8080",parent_section_name=""} 1
outbound_tcp_detect_http_results_total{result="error",parent_group="core",parent_kind="Service",parent_namespace="emojivoto",parent_name="voting-svc",parent_port="8080",parent_section_name=""} 0
outbound_tcp_detect_http_results_total{result="http/1",parent_group="core",parent_kind="Service",parent_namespace="emojivoto",parent_name="emoji-svc",parent_port="8080",parent_section_name=""} 0
outbound_tcp_detect_http_results_total{result="h2",parent_group="core",parent_kind="Service",parent_namespace="emojivoto",parent_name="emoji-svc",parent_port="8080",parent_section_name=""} 1
outbound_tcp_detect_http_results_total{result="error",parent_group="core",parent_kind="Service",parent_namespace="emojivoto",parent_name="emoji-svc",parent_port="8080",parent_section_name=""} 0
outbound_tcp_detect_http_results_total{result="read_timeout",parent_group="core",parent_kind="Service",parent_namespace="emojivoto",parent_name="emoji-svc",parent_port="8080",parent_section_name=""} 0

[cratelyn]

💐 ✨ nice! i am very excited for how helpful these new metrics will be in debugging various issues related to protocol detection. this will be a great step forward in our observability story, on that front.