Move the network resolver out (#1944)

resolver/http/http.go

@@ -0,0 +1,78 @@
+// Package http resolves names to network addresses using a http request
+package http
+
+import (
+	"encoding/json"
+	"errors"
+	"io/ioutil"
+	"net/http"
+	"net/url"
+
+	"github.com/micro/go-micro/v3/resolver"
+)
+
+// Resolver is a HTTP network resolver
+type Resolver struct {
+	// If not set, defaults to http
+	Proto string
+
+	// Path sets the path to lookup. Defaults to /network
+	Path string
+
+	// Host url to use for the query
+	Host string
+}
+
+type Response struct {
+	Nodes []*resolver.Record `json:"nodes,omitempty"`
+}
+
+// Resolve assumes ID is a domain which can be converted to a http://name/network request
+func (r *Resolver) Resolve(name string) ([]*resolver.Record, error) {
+	proto := "http"
+	host := "localhost:8080"
+	path := "/network/nodes"
+
+	if len(r.Proto) > 0 {
+		proto = r.Proto
+	}
+
+	if len(r.Path) > 0 {
+		path = r.Path
+	}
+
+	if len(r.Host) > 0 {
+		host = r.Host
+	}
+
+	uri := &url.URL{
+		Scheme: proto,
+		Path:   path,
+		Host:   host,
+	}
+	q := uri.Query()
+	q.Set("name", name)
+	uri.RawQuery = q.Encode()
+
+	rsp, err := http.Get(uri.String())
+	if err != nil {
+		return nil, err
+	}
+	defer rsp.Body.Close()
+	if rsp.StatusCode != 200 {
+		return nil, errors.New("non 200 response")
+	}
+	b, err := ioutil.ReadAll(rsp.Body)
+	if err != nil {
+		return nil, err
+	}
+
+	// encoding format is assumed to be json
+	var response *Response
+
+	if err := json.Unmarshal(b, &response); err != nil {
+		return nil, err
+	}
+
+	return response.Nodes, nil
+}