etcd: refactor config

- Explicitly specify all of the valid options for etcd
- Remove the default name generation (ETCD_NAME is set by its unit file now)
- Seperate the etcd config from Units()
- Remove support for DISCOVERY_URL
- Add YAML tags for the fields

system/env.go

@@ -0,0 +1,26 @@
+package system
+
+import (
+	"fmt"
+	"reflect"
+)
+
+// dropinContents generates the contents for a drop-in unit given the config.
+// The argument must be a struct from the 'config' package.
+func dropinContents(e interface{}) string {
+	et := reflect.TypeOf(e)
+	ev := reflect.ValueOf(e)
+
+	var out string
+	for i := 0; i < et.NumField(); i++ {
+		if val := ev.Field(i).String(); val != "" {
+			key := et.Field(i).Tag.Get("env")
+			out += fmt.Sprintf("Environment=\"%s=%s\"\n", key, val)
+		}
+	}
+
+	if out == "" {
+		return ""
+	}
+	return "[Service]\n" + out
+}

system/etcd.go

@@ -0,0 +1,25 @@
+package system
+
+import (
+	"github.com/coreos/coreos-cloudinit/config"
+)
+
+// Etcd is a top-level structure which embeds its underlying configuration,
+// config.Etcd, and provides the system-specific Unit().
+type Etcd struct {
+	config.Etcd
+}
+
+// Units creates a Unit file drop-in for etcd, using any configured options.
+func (ee Etcd) Units(_ string) ([]Unit, error) {
+	content := dropinContents(ee.Etcd)
+	if content == "" {
+		return nil, nil
+	}
+	return []Unit{{
+		Name:    "etcd.service",
+		Runtime: true,
+		DropIn:  true,
+		Content: content,
+	}}, nil
+}

system/etcd_test.go

@@ -0,0 +1,60 @@
+package system
+
+import (
+	"reflect"
+	"testing"
+
+	"github.com/coreos/coreos-cloudinit/config"
+)
+
+func TestEtcdUnits(t *testing.T) {
+	for _, tt := range []struct {
+		config config.Etcd
+		units  []Unit
+	}{
+		{
+			config.Etcd{},
+			nil,
+		},
+		{
+			config.Etcd{
+				Discovery:    "http://disco.example.com/foobar",
+				PeerBindAddr: "127.0.0.1:7002",
+			},
+			[]Unit{{
+				Name:    "etcd.service",
+				Runtime: true,
+				DropIn:  true,
+				Content: `[Service]
+Environment="ETCD_DISCOVERY=http://disco.example.com/foobar"
+Environment="ETCD_PEER_BIND_ADDR=127.0.0.1:7002"
+`,
+			}},
+		},
+		{
+			config.Etcd{
+				Name:         "node001",
+				Discovery:    "http://disco.example.com/foobar",
+				PeerBindAddr: "127.0.0.1:7002",
+			},
+			[]Unit{{
+				Name:    "etcd.service",
+				Runtime: true,
+				DropIn:  true,
+				Content: `[Service]
+Environment="ETCD_DISCOVERY=http://disco.example.com/foobar"
+Environment="ETCD_NAME=node001"
+Environment="ETCD_PEER_BIND_ADDR=127.0.0.1:7002"
+`,
+			}},
+		},
+	} {
+		units, err := Etcd{tt.config}.Units("")
+		if err != nil {
+			t.Errorf("bad error (%q): want %q, got %q", tt.config, nil, err)
+		}
+		if !reflect.DeepEqual(tt.units, units) {
+			t.Errorf("bad units (%q): want %#v, got %#v", tt.config, tt.units, units)
+		}
+	}
+}