Add domain-source config flag

This is an incremental step for adding `-domain-source`
as described in https://gitlab.com/gitlab-org/gitlab/-/issues/217912.
We are only adding the flag here but it's not doing anything at the
moment.

Add TODO for implementation

3 files changed, 11 insertions, 2 deletions

diff --git a/internal/source/domains.go b/internal/source/domains.go
index 8de7c574..e2d24a67 100644
--- a/internal/source/domains.go
+++ b/internal/source/domains.go
@@ -41,6 +41,9 @@ type Domains struct {
 // not initialize `dm` as we later check the readiness by comparing it with a
 // nil value.
 func NewDomains(config Config) (*Domains, error) {
+	// TODO: choose domain source config via config.DomainSourceConfig()
+	// https://gitlab.com/gitlab-org/gitlab/-/issues/217912
+
 	if len(config.InternalGitLabServerURL()) == 0 || len(config.GitlabAPISecret()) == 0 {
 		return &Domains{disk: disk.New()}, nil
 	}
diff --git a/internal/source/domains_test.go b/internal/source/domains_test.go
index ebafb6fc..4a328a3c 100644
--- a/internal/source/domains_test.go
+++ b/internal/source/domains_test.go
@@ -12,8 +12,9 @@ import (
 )
 
 type sourceConfig struct {
-	api    string
-	secret string
+	api          string
+	secret       string
+	domainSource string
 }
 
 func (c sourceConfig) InternalGitLabServerURL() string {
@@ -31,6 +32,10 @@ func (c sourceConfig) GitlabJWTTokenExpiry() time.Duration {
 	return 30 * time.Second
 }
 
+func (c sourceConfig) DomainSourceConfig() string {
+	return c.domainSource
+}
+
 func TestDomainSources(t *testing.T) {
 	t.Run("when GitLab API URL has been provided", func(t *testing.T) {
 		domains, err := NewDomains(sourceConfig{api: "https://gitlab.com", secret: "abc"})
diff --git a/internal/source/gitlab/client/config.go b/internal/source/gitlab/client/config.go
index 19a87452..51b75025 100644
--- a/internal/source/gitlab/client/config.go
+++ b/internal/source/gitlab/client/config.go
@@ -9,4 +9,5 @@ type Config interface {
 	GitlabAPISecret() []byte
 	GitlabClientConnectionTimeout() time.Duration
 	GitlabJWTTokenExpiry() time.Duration
+	DomainSourceConfig() string
 }