/
httpclient.go
125 lines (104 loc) · 3.04 KB
/
httpclient.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
// +build go1.7
package svc1
import (
"context"
"fmt"
"io/ioutil"
"net/http"
"net/url"
"strconv"
opentracing "github.com/opentracing/opentracing-go"
"github.com/openzipkin-contrib/zipkin-go-opentracing/examples/middleware"
)
// client is our actual client implementation
type client struct {
baseURL string
httpClient *http.Client
tracer opentracing.Tracer
traceRequest middleware.RequestFunc
}
// Concat implements our Service interface.
func (c *client) Concat(ctx context.Context, a, b string) (string, error) {
// create new span using span found in context as parent (if none is found,
// our span becomes the trace root).
span, ctx := opentracing.StartSpanFromContext(ctx, "Concat")
defer span.Finish()
// assemble URL query
url := fmt.Sprintf(
"%s/concat/?a=%s&b=%s", c.baseURL, url.QueryEscape(a), url.QueryEscape(b),
)
// create the HTTP request
req, err := http.NewRequest("GET", url, nil)
if err != nil {
return "", err
}
// use our middleware to propagate our trace
req = c.traceRequest(req.WithContext(ctx))
// execute the HTTP request
resp, err := c.httpClient.Do(req)
if err != nil {
// annotate our span with the error condition
span.SetTag("error", err.Error())
return "", err
}
defer resp.Body.Close()
// read the http response body
data, err := ioutil.ReadAll(resp.Body)
if err != nil {
// annotate our span with the error condition
span.SetTag("error", err.Error())
return "", err
}
// return the result
return string(data), nil
}
// Sum implements our Service interface.
func (c *client) Sum(ctx context.Context, a, b int64) (int64, error) {
// create new span using span found in context as parent (if none is found,
// our span becomes the trace root).
span, ctx := opentracing.StartSpanFromContext(ctx, "Sum")
defer span.Finish()
// assemble URL query
url := fmt.Sprintf("%s/sum/?a=%d&b=%d", c.baseURL, a, b)
// create the HTTP request
req, err := http.NewRequest("GET", url, nil)
if err != nil {
return 0, err
}
// use our middleware to propagate our trace
req = c.traceRequest(req.WithContext(ctx))
// execute the HTTP request
resp, err := c.httpClient.Do(req)
if err != nil {
// annotate our span with the error condition
span.SetTag("error", err.Error())
return 0, err
}
defer resp.Body.Close()
// read the http response body
data, err := ioutil.ReadAll(resp.Body)
if err != nil {
// annotate our span with the error condition
span.SetTag("error", err.Error())
return 0, err
}
// convert html response to expected result type (int64)
result, err := strconv.ParseInt(string(data), 10, 64)
if err != nil {
// annotate our span with the error condition
span.SetTag("error", err.Error())
return 0, err
}
// return the result
return result, nil
}
// NewHTTPClient returns a new client instance to our svc1 using the HTTP
// transport.
func NewHTTPClient(tracer opentracing.Tracer, baseURL string) Service {
return &client{
baseURL: baseURL,
httpClient: &http.Client{},
tracer: tracer,
traceRequest: middleware.ToHTTPRequest(tracer),
}
}