add leveldb store

1. switch to viper for filer store configuration
2. simplify FindEntry() return values, removing “found”
3. add leveldb store

weed/filer2/configuration.go

@@ -0,0 +1,87 @@
+package filer2
+
+import (
+	"os"
+
+	"github.com/spf13/viper"
+	"github.com/chrislusf/seaweedfs/weed/glog"
+)
+
+const (
+	FILER_TOML_EXAMPLE = `
+# A sample TOML config file for SeaweedFS filer store
+
+# local in memory, mostly for testing purpose
+[memory]
+enabled = false
+
+[leveldb]
+enabled = false
+dir = "."					# directory to store level db files
+
+[mysql]
+enabled = true
+server = "192.168.1.1"
+port = 8080
+username = ""
+password = ""
+database = ""
+connection_max_idle = 100
+connection_max_open = 100
+
+[postgres]
+enabled = false
+server = "192.168.1.1"
+port = 8080
+username = ""
+password = ""
+database = ""
+connection_max_idle = 100
+connection_max_open = 100
+
+`
+)
+
+var (
+	Stores []FilerStore
+)
+
+func (f *Filer) LoadConfiguration() {
+
+	// find a filer store
+	viper.SetConfigName("filer")            // name of config file (without extension)
+	viper.AddConfigPath(".")                // optionally look for config in the working directory
+	viper.AddConfigPath("$HOME/.seaweedfs") // call multiple times to add many search paths
+	viper.AddConfigPath("/etc/seaweedfs/")  // path to look for the config file in
+	if err := viper.ReadInConfig(); err != nil { // Handle errors reading the config file
+		glog.Fatalf("Failed to load filer.toml file from current directory, or $HOME/.seaweedfs/, or /etc/seaweedfs/" +
+			"\n\nPlease follow this example and add a filer.toml file to " +
+			"current directory, or $HOME/.seaweedfs/, or /etc/seaweedfs/:\n" + FILER_TOML_EXAMPLE)
+	}
+
+	glog.V(0).Infof("Reading filer configuration from %s", viper.ConfigFileUsed())
+	for _, store := range Stores {
+		if viper.GetBool(store.GetName() + ".enabled") {
+			viperSub := viper.Sub(store.GetName())
+			if err := store.Initialize(viperSub); err != nil {
+				glog.Fatalf("Failed to initialize store for %s: %+v",
+					store.GetName(), err)
+			}
+			f.SetStore(store)
+			glog.V(0).Infof("Configure filer for %s from %s", store.GetName(), viper.ConfigFileUsed())
+			return
+		}
+	}
+
+	println()
+	println("Supported filer stores are:")
+	for _, store := range Stores {
+		println("    " + store.GetName())
+	}
+
+	println()
+	println("Please configure a supported filer store in", viper.ConfigFileUsed())
+	println()
+
+	os.Exit(-1)
+}