Adapt for Enterprise version - respect GITHUB ENV variables (#52)

Co-authored-by: wojciech.sielski <wojciech.sielski@adevinta.com>

main.go

@@ -96,13 +96,23 @@ func newCommentLoopChannel(ctx context.Context, apprv *approvalEnvironment, clie
 	return channel
 }
 
-func newGithubClient(ctx context.Context) *github.Client {
+func newGithubClient(ctx context.Context) (*github.Client, error) {
 	token := os.Getenv(envVarToken)
 	ts := oauth2.StaticTokenSource(
 		&oauth2.Token{AccessToken: token},
 	)
 	tc := oauth2.NewClient(ctx, ts)
-	return github.NewClient(tc)
+
+	serverUrl, serverUrlPresent := os.LookupEnv("GITHUB_SERVER_URL")
+	apiUrl, apiUrlPresent := os.LookupEnv("GITHUB_API_URL")
+
+	if serverUrlPresent {
+		if ! apiUrlPresent {
+			apiUrl = serverUrl
+		}
+		return github.NewEnterpriseClient(apiUrl, serverUrl, tc)
+	}
+	return github.NewClient(tc), nil
 }
 
 func validateInput() error {
@@ -148,7 +158,11 @@ func main() {
 	repoOwner := os.Getenv(envVarRepoOwner)
 
 	ctx := context.Background()
-	client := newGithubClient(ctx)
+	client, err := newGithubClient(ctx)
+	if err != nil {
+		fmt.Printf("error connecting to server: %v\n", err)
+		os.Exit(1)
+	}
 
 	approvers, err := retrieveApprovers(client, repoOwner)
 	if err != nil {