Add config loading and dry-run validation

internal/config/defaults.go

@@ -1,3 +1,50 @@
 package config
 
 const DefaultConfigPath = "/usr/local/etc/distributor/config.yml"
+
+const (
+	BackendLocal = "local"
+	BackendSSH   = "ssh"
+	BackendS3    = "s3"
+)
+
+const (
+	ValidationActionFail = "fail"
+)
+
+const (
+	TransferActionSkip    = "skip"
+	TransferActionReplace = "replace"
+	TransferActionFail    = "fail"
+)
+
+const (
+	TransformModeSidecar = "sidecar"
+)
+
+func ApplyDefaults(cfg *Config) {
+	for pipelineIndex := range cfg.Pipelines {
+		pipeline := &cfg.Pipelines[pipelineIndex]
+		if pipeline.Validation.OnDigestMismatch == "" {
+			pipeline.Validation.OnDigestMismatch = ValidationActionFail
+		}
+		for destinationIndex := range pipeline.Destinations {
+			destination := &pipeline.Destinations[destinationIndex]
+			if destination.Publish == nil {
+				destination.Publish = &PublishPolicy{Source: true}
+			}
+			if destination.Transfer.OnDestinationSame == "" {
+				destination.Transfer.OnDestinationSame = TransferActionSkip
+			}
+			if destination.Transfer.OnDestinationOlder == "" {
+				destination.Transfer.OnDestinationOlder = TransferActionReplace
+			}
+			if destination.Transfer.OnDestinationNewer == "" {
+				destination.Transfer.OnDestinationNewer = TransferActionSkip
+			}
+			if destination.Transfer.OnConflict == "" {
+				destination.Transfer.OnConflict = TransferActionFail
+			}
+		}
+	}
+}