Added dry run flag to agentctl config-sync cmd (#68)

* Added dry run flag to agentctl config-sync cmd

* Simplify test, replace print with logger

cmd/agentctl/main.go

@@ -33,6 +33,7 @@ func main() {
 func configSyncCmd() *cobra.Command {
 	var (
 		agentAddr string
+		dryRun    bool
 	)
 
 	cmd := &cobra.Command{
@@ -55,7 +56,7 @@ source-of-truth directory.`,
 
 			logger := log.NewLogfmtLogger(log.NewSyncWriter(os.Stdout))
 
-			err := agentctl.ConfigSync(logger, cli.PrometheusClient, directory)
+			err := agentctl.ConfigSync(logger, cli.PrometheusClient, directory, dryRun)
 			if err != nil {
 				level.Error(logger).Log("msg", "failed to sync config", "err", err)
 				os.Exit(1)
@@ -64,6 +65,7 @@ source-of-truth directory.`,
 	}
 
 	cmd.Flags().StringVarP(&agentAddr, "addr", "a", "http://localhost:12345", "address of the agent to connect to")
+	cmd.Flags().BoolVarP(&dryRun, "dry-run", "d", false, "use the dry run option to validate config files without attempting to upload")
 	must(cmd.MarkFlagRequired("addr"))
 	return cmd
 }

pkg/agentctl/sync.go

@@ -25,22 +25,22 @@ import (
 // ConfigSync will completely overwrite the set of active configs
 // present in the provided PrometheusClient - configs present in the
 // API but not in the directory will be deleted.
-func ConfigSync(logger log.Logger, cli client.PrometheusClient, dir string) error {
+func ConfigSync(logger log.Logger, cli client.PrometheusClient, dir string, dryRun bool) error {
 	if logger == nil {
 		logger = log.NewNopLogger()
 	}
 
 	ctx := context.Background()
-	existing, err := cli.ListConfigs(ctx)
-	if err != nil {
-		return fmt.Errorf("could not list configs: %w", err)
-	}
-
 	cfgs, err := ConfigsFromDirectory(dir)
 	if err != nil {
 		return err
 	}
 
+	if dryRun {
+		level.Info(logger).Log("msg", "config files validated successfully")
+		return nil
+	}
+
 	uploaded := make(map[string]struct{}, len(cfgs))
 	var hadErrors bool
 
@@ -54,6 +54,11 @@ func ConfigSync(logger log.Logger, cli client.PrometheusClient, dir string) erro
 		uploaded[cfg.Name] = struct{}{}
 	}
 
+	existing, err := cli.ListConfigs(ctx)
+	if err != nil {
+		return fmt.Errorf("could not list configs: %w", err)
+	}
+
 	// Delete configs from the existing API list that we didn't upload.
 	for _, existing := range existing.Configs {
 		if _, existsLocally := uploaded[existing]; !existsLocally {

pkg/agentctl/sync_test.go

@@ -22,7 +22,7 @@ func TestConfigSync_EmptyStore(t *testing.T) {
 		return nil
 	}
 
-	err := ConfigSync(nil, cli, "./testdata")
+	err := ConfigSync(nil, cli, "./testdata", false)
 	require.NoError(t, err)
 
 	expect := []string{
@@ -53,7 +53,7 @@ func TestConfigSync_PrepopulatedStore(t *testing.T) {
 		return nil
 	}
 
-	err := ConfigSync(nil, cli, "./testdata")
+	err := ConfigSync(nil, cli, "./testdata", false)
 	require.NoError(t, err)
 
 	expectUpdated := []string{
@@ -71,6 +71,28 @@ func TestConfigSync_PrepopulatedStore(t *testing.T) {
 	require.Equal(t, expectDeleted, deletedConfigs)
 }
 
+func TestConfigSync_DryRun(t *testing.T) {
+	cli := &mockFuncPromClient{}
+	cli.ListConfigsFunc = func(_ context.Context) (*configapi.ListConfigurationsResponse, error) {
+		return &configapi.ListConfigurationsResponse{
+			Configs: []string{"delete-a", "agent-1", "delete-b", "delete-c"},
+		}, nil
+	}
+
+	cli.PutConfigurationFunc = func(_ context.Context, name string, _ *instance.Config) error {
+		t.FailNow()
+		return nil
+	}
+
+	cli.DeleteConfigurationFunc = func(_ context.Context, name string) error {
+		t.FailNow()
+		return nil
+	}
+
+	err := ConfigSync(nil, cli, "./testdata", true)
+	require.NoError(t, err)
+}
+
 type mockFuncPromClient struct {
 	InstancesFunc           func(ctx context.Context) ([]string, error)
 	ListConfigsFunc         func(ctx context.Context) (*configapi.ListConfigurationsResponse, error)