feat: fail on startup if instance uri is invalid (#210)

cmd/root.go

@@ -534,13 +534,15 @@ func parseConfig(cmd *Command, conf *proxy.Config, args []string) error {
 
 	var ics []proxy.InstanceConnConfig
 	for _, a := range args {
-		// Assume no query params initially
-		ic := proxy.InstanceConnConfig{
-			Name: a,
+		// split into instance uri and query parameters
+		res := strings.SplitN(a, "?", 2)
+		_, _, _, _, err := proxy.ParseInstanceURI(res[0])
+		if err != nil {
+			return newBadCommandError(fmt.Sprintf("could not parse instance uri: %q", res[0]))
 		}
+		ic := proxy.InstanceConnConfig{Name: res[0]}
 		// If there are query params, update instance config.
-		if res := strings.SplitN(a, "?", 2); len(res) > 1 {
-			ic.Name = res[0]
+		if len(res) > 1 {
 			q, err := url.ParseQuery(res[1])
 			if err != nil {
 				return newBadCommandError(fmt.Sprintf("could not parse query: %q", res[1]))

cmd/root_test.go

@@ -637,6 +637,10 @@ func TestNewCommandWithErrors(t *testing.T) {
 			desc: "basic invocation missing instance connection name",
 			args: []string{},
 		},
+		{
+			desc: "when the instance uri is bogus",
+			args: []string{"projects/proj/locations/region/clusters/clust/"},
+		},
 		{
 			desc: "when the query string is bogus",
 			args: []string{"projects/proj/locations/region/clusters/clust/instances/inst?%=foo"},
@@ -832,7 +836,7 @@ func TestPrometheusMetricsEndpoint(t *testing.T) {
 	// Keep the test output quiet
 	c.SilenceUsage = true
 	c.SilenceErrors = true
-	c.SetArgs([]string{"--prometheus", "my-project:my-region:my-instance"})
+	c.SetArgs([]string{"--prometheus", "projects/my-project/locations/my-region/clusters/my-cluster/instances/my-instance"})
 
 	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
 	defer cancel()

internal/proxy/proxy.go

@@ -235,24 +235,29 @@ var (
 	unixRegex = regexp.MustCompile(`([^:]+(?:-[^:]+)?)\.(.+)\.(.+)\.(.+)`)
 )
 
+// ParseInstanceURI validates the instance uri is in the proper format and
+// returns the project, region, cluster, and instance name.
+func ParseInstanceURI(inst string) (string, string, string, string, error) {
+	m := instURIRegex.FindSubmatch([]byte(inst))
+	if m == nil {
+		return "", "", "", "", fmt.Errorf("invalid instance name: %v", inst)
+	}
+	return string(m[1]), string(m[2]), string(m[3]), string(m[4]), nil
+}
+
 // UnixSocketDir returns a shorted instance connection name to prevent
 // exceeding the Unix socket length, e.g., project.region.cluster.instance
 func UnixSocketDir(dir, inst string) (string, error) {
-	inst = strings.ToLower(inst)
-	m := instURIRegex.FindSubmatch([]byte(inst))
-	if m == nil {
-		return "", fmt.Errorf("invalid instance name: %v", inst)
+	project, region, cluster, name, err := ParseInstanceURI(strings.ToLower(inst))
+	if err != nil {
+		return "", err
 	}
-	project := string(m[1])
 	// Colons are not allowed on Windows, but are present in legacy project
 	// names (e.g., google.com:myproj). Replace any colon with an underscore to
 	// support Windows. Underscores are not allowed in project names. So use an
 	// underscore to have a Windows-friendly delimitor that can serve as a
 	// marker to recover the legacy project name when necessary (e.g., FUSE).
 	project = strings.ReplaceAll(project, ":", "_")
-	region := string(m[2])
-	cluster := string(m[3])
-	name := string(m[4])
 	shortName := strings.Join([]string{project, region, cluster, name}, ".")
 	return filepath.Join(dir, shortName), nil
 }