/
chi.go
141 lines (129 loc) · 3.64 KB
/
chi.go
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
package otelchi
import (
"fmt"
"go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp"
"net/http"
"sync"
"github.com/felixge/httpsnoop"
"github.com/go-chi/chi/v5"
otelcontrib "go.opentelemetry.io/contrib"
"go.opentelemetry.io/otel"
"go.opentelemetry.io/otel/propagation"
"go.opentelemetry.io/otel/semconv/v1.7.0"
oteltrace "go.opentelemetry.io/otel/trace"
)
const (
tracerName = "github.com/yacchi/otelchi"
)
// Middleware sets up a handler to start tracing the incoming
// requests. The service parameter should describe the name of the
// (virtual) server handling the request.
func Middleware(service string, opts ...Option) func(http.Handler) http.Handler {
cfg := config{}
for _, opt := range opts {
opt(&cfg)
}
if cfg.TracerProvider == nil {
cfg.TracerProvider = otel.GetTracerProvider()
}
tracer := cfg.TracerProvider.Tracer(
tracerName,
oteltrace.WithInstrumentationVersion(otelcontrib.SemVersion()),
)
if cfg.Propagators == nil {
cfg.Propagators = otel.GetTextMapPropagator()
}
return func(handler http.Handler) http.Handler {
return traceware{
service: service,
tracer: tracer,
propagators: cfg.Propagators,
handler: handler,
filters: cfg.Filters,
}
}
}
type traceware struct {
service string
tracer oteltrace.Tracer
propagators propagation.TextMapPropagator
handler http.Handler
filters []otelhttp.Filter
}
type recordingResponseWriter struct {
writer http.ResponseWriter
written bool
status int
}
var rrwPool = &sync.Pool{
New: func() interface{} {
return &recordingResponseWriter{}
},
}
func getRRW(writer http.ResponseWriter) *recordingResponseWriter {
rrw := rrwPool.Get().(*recordingResponseWriter)
rrw.written = false
rrw.status = 0
rrw.writer = httpsnoop.Wrap(writer, httpsnoop.Hooks{
Write: func(next httpsnoop.WriteFunc) httpsnoop.WriteFunc {
return func(b []byte) (int, error) {
if !rrw.written {
rrw.written = true
rrw.status = http.StatusOK
}
return next(b)
}
},
WriteHeader: func(next httpsnoop.WriteHeaderFunc) httpsnoop.WriteHeaderFunc {
return func(statusCode int) {
if !rrw.written {
rrw.written = true
rrw.status = statusCode
}
next(statusCode)
}
},
})
return rrw
}
func putRRW(rrw *recordingResponseWriter) {
rrw.writer = nil
rrwPool.Put(rrw)
}
// ServeHTTP implements the http.Handler interface. It does the actual
// tracing of the request.
func (t traceware) ServeHTTP(w http.ResponseWriter, r *http.Request) {
for _, f := range t.filters {
if !f(r) {
// Simply pass through to the handler if a filter rejects the request
t.handler.ServeHTTP(w, r)
return
}
}
ctx := t.propagators.Extract(r.Context(), propagation.HeaderCarrier(r.Header))
spanName := ""
route := chi.RouteContext(ctx)
if route != nil {
spanName = route.RoutePattern()
}
routeStr := spanName
if spanName == "" {
spanName = fmt.Sprintf("HTTP %s route not found", r.Method)
}
opts := []oteltrace.SpanStartOption{
oteltrace.WithAttributes(semconv.NetAttributesFromHTTPRequest("tcp", r)...),
oteltrace.WithAttributes(semconv.EndUserAttributesFromHTTPRequest(r)...),
oteltrace.WithAttributes(semconv.HTTPServerAttributesFromHTTPRequest(t.service, routeStr, r)...),
oteltrace.WithSpanKind(oteltrace.SpanKindServer),
}
ctx, span := t.tracer.Start(ctx, spanName, opts...)
defer span.End()
r2 := r.WithContext(ctx)
rrw := getRRW(w)
defer putRRW(rrw)
t.handler.ServeHTTP(rrw.writer, r2)
attrs := semconv.HTTPAttributesFromHTTPStatusCode(rrw.status)
spanStatus, spanMessage := semconv.SpanStatusFromHTTPStatusCode(rrw.status)
span.SetAttributes(attrs...)
span.SetStatus(spanStatus, spanMessage)
}