Fix versioning for planetscale-go headers (#218)

* Fix user agents for planetscale-go

* Get version from dependency path, rather than from main module

planetscale/client.go

@@ -8,6 +8,7 @@ import (
 	"io"
 	"net/http"
 	"net/url"
+	"runtime/debug"
 	"strconv"
 
 	"github.com/hashicorp/go-cleanhttp"
@@ -20,11 +21,6 @@ const (
 	jsonMediaType  = "application/json"
 )
 
-const (
-	libraryVersion = "v0.67.0"
-	userAgent      = "planetscale-go/" + libraryVersion
-)
-
 // ErrorCode defines the code of an error.
 type ErrorCode string
 
@@ -133,6 +129,21 @@ func WithPerPage(perPage int) ListOption {
 // ClientOption provides a variadic option for configuring the client
 type ClientOption func(c *Client) error
 
+func defaultUserAgent() string {
+	libraryVersion := "unknown"
+	buildInfo, ok := debug.ReadBuildInfo()
+	if ok {
+		for _, dep := range buildInfo.Deps {
+			if dep.Path == "github.com/planetscale/planetscale-go" {
+				libraryVersion = dep.Version
+				break
+			}
+		}
+	}
+
+	return "planetscale-go/" + libraryVersion
+}
+
 // WithUserAgent overrides the User-Agent header.
 func WithUserAgent(userAgent string) ClientOption {
 	return func(c *Client) error {
@@ -223,7 +234,7 @@ func NewClient(opts ...ClientOption) (*Client, error) {
 	c := &Client{
 		client:    cleanhttp.DefaultClient(),
 		baseURL:   baseURL,
-		UserAgent: userAgent,
+		UserAgent: defaultUserAgent(),
 		headers:   make(map[string]string, 0),
 	}
 

planetscale/client_test.go

@@ -28,7 +28,7 @@ func TestDo(t *testing.T) {
 			response:   `{}`,
 			method:     http.MethodGet,
 			wantHeaders: map[string]string{
-				"User-Agent": "planetscale-go/v0.67.0",
+				"User-Agent": "planetscale-go/unknown",
 			},
 		},
 		{
@@ -39,7 +39,7 @@ func TestDo(t *testing.T) {
 			clientOptions: []ClientOption{WithUserAgent("test-user-agent"), WithRequestHeaders(map[string]string{"Test-Header": "test-value"})},
 			wantHeaders: map[string]string{
 				"Test-Header": "test-value",
-				"User-Agent":  "test-user-agent planetscale-go/v0.67.0",
+				"User-Agent":  "test-user-agent planetscale-go/unknown",
 			},
 		},
 		{