add otel module based on uptrace-go

Signed-off-by: Adphi <philippe.adrien.nousse@gmail.com>

otel/dsn.go

@@ -0,0 +1,103 @@
+package otel
+
+import (
+	"encoding/base64"
+	"fmt"
+	"net"
+	"net/url"
+)
+
+type DSN struct {
+	original string
+
+	Scheme   string
+	Host     string
+	HTTPPort string
+	User     string
+	Password string
+	Token    string
+}
+
+func (dsn *DSN) String() string {
+	return dsn.original
+}
+
+func (dsn *DSN) SiteURL() string {
+	return dsn.Scheme + "://" + joinHostPort(dsn.Host, dsn.HTTPPort)
+}
+
+func (dsn *DSN) OTLPHttpEndpoint() string {
+	return joinHostPort(dsn.Host, dsn.HTTPPort)
+}
+
+func (dsn *DSN) Headers() map[string]string {
+	if dsn.Token != "" {
+		return map[string]string{
+			"Authorization": "Bearer " + dsn.Token,
+		}
+	}
+	if dsn.User != "" && dsn.Password != "" {
+		return map[string]string{
+			"Authorization": "Basic " + base64.StdEncoding.EncodeToString([]byte(dsn.User+":"+dsn.Password)),
+		}
+	}
+	return nil
+}
+
+func ParseDSN(dsnStr string) (*DSN, error) {
+	if dsnStr == "" {
+		return nil, fmt.Errorf("DSN is empty (use WithDSN or OTEL_DSN env var)")
+	}
+
+	u, err := url.Parse(dsnStr)
+	if err != nil {
+		return nil, fmt.Errorf("can't parse DSN=%q: %s", dsnStr, err)
+	}
+
+	switch u.Scheme {
+	case "http", "https":
+	case "":
+		return nil, fmt.Errorf("DSN=%q does not have a scheme", dsnStr)
+	default:
+		return nil, fmt.Errorf("DSN=%q has unsupported scheme %q", dsnStr, u.Scheme)
+	}
+
+	if u.Host == "" {
+		return nil, fmt.Errorf("DSN=%q does not have a host", dsnStr)
+	}
+
+	dsn := DSN{
+		original: dsnStr,
+		Scheme:   u.Scheme,
+		Host:     u.Host,
+	}
+	if p, ok := u.User.Password(); ok {
+		dsn.User = u.User.Username()
+		dsn.Password = p
+	} else {
+		dsn.Token = u.User.Username()
+	}
+
+	if host, port, err := net.SplitHostPort(u.Host); err == nil {
+		dsn.Host = host
+		dsn.HTTPPort = port
+	}
+
+	if dsn.HTTPPort == "" {
+		switch dsn.Scheme {
+		case "http":
+			dsn.HTTPPort = "80"
+		case "https":
+			dsn.HTTPPort = "443"
+		}
+	}
+
+	return &dsn, nil
+}
+
+func joinHostPort(host, port string) string {
+	if port == "" {
+		return host
+	}
+	return net.JoinHostPort(host, port)
+}