add config

config/loader/loader.go

@@ -0,0 +1,63 @@
+// package loader manages loading from multiple sources
+package loader
+
+import (
+	"context"
+
+	"github.com/micro/go-micro/config/reader"
+	"github.com/micro/go-micro/config/source"
+)
+
+// Loader manages loading sources
+type Loader interface {
+	// Stop the loader
+	Close() error
+	// Load the sources
+	Load(...source.Source) error
+	// A Snapshot of loaded config
+	Snapshot() (*Snapshot, error)
+	// Force sync of sources
+	Sync() error
+	// Watch for changes
+	Watch(...string) (Watcher, error)
+	// Name of loader
+	String() string
+}
+
+// Watcher lets you watch sources and returns a merged ChangeSet
+type Watcher interface {
+	// First call to next may return the current Snapshot
+	// If you are watching a path then only the data from
+	// that path is returned.
+	Next() (*Snapshot, error)
+	// Stop watching for changes
+	Stop() error
+}
+
+// Snapshot is a merged ChangeSet
+type Snapshot struct {
+	// The merged ChangeSet
+	ChangeSet *source.ChangeSet
+	// Deterministic and comparable version of the snapshot
+	Version string
+}
+
+type Options struct {
+	Reader reader.Reader
+	Source []source.Source
+
+	// for alternative data
+	Context context.Context
+}
+
+type Option func(o *Options)
+
+// Copy snapshot
+func Copy(s *Snapshot) *Snapshot {
+	cs := *(s.ChangeSet)
+
+	return &Snapshot{
+		ChangeSet: &cs,
+		Version:   s.Version,
+	}
+}