Merge pull request #32 from bcwaldon/etcd-name

feat(etcd): Default etcd name to /etc/machine-id

initialize/etcd.go

@@ -1,6 +1,7 @@
 package initialize
 
 import (
+	"errors"
 	"fmt"
 	"os"
 	"path"
@@ -31,11 +32,22 @@ func (ec EtcdEnvironment) String() (out string) {
 
 		out += fmt.Sprintf("Environment=\"ETCD_%s=%s\"\n", key, val)
 	}
+
 	return
 }
 
 // Write an EtcdEnvironment to the appropriate path on disk for etcd.service
 func WriteEtcdEnvironment(env EtcdEnvironment, root string) error {
+	if _, ok := env["name"]; !ok {
+		if machineID := system.MachineID(root); machineID != "" {
+			env["name"] = machineID
+		} else if hostname, err := system.Hostname(); err == nil {
+			env["name"] = hostname
+		} else {
+			return errors.New("Unable to determine default etcd name")
+		}
+	}
+
 	file := system.File{
 		Path: path.Join(root, "run", "systemd", "system", "etcd.service.d", "20-cloudinit.conf"),
 		RawFilePermissions: "0644",

initialize/etcd_test.go

@@ -46,6 +46,7 @@ Environment="ETCD_PEER_BIND_ADDR=192.0.2.13:7001"
 
 func TestEtcdEnvironmentWrittenToDisk(t *testing.T) {
 	ec := EtcdEnvironment{
+		"name": "node001",
 		"discovery_url": "http://disco.example.com/foobar",
 		"peer-bind-addr": "127.0.0.1:7002",
 	}
@@ -76,6 +77,7 @@ func TestEtcdEnvironmentWrittenToDisk(t *testing.T) {
 	}
 
 	expect := `[Service]
+Environment="ETCD_NAME=node001"
 Environment="ETCD_DISCOVERY_URL=http://disco.example.com/foobar"
 Environment="ETCD_PEER_BIND_ADDR=127.0.0.1:7002"
 `
@@ -84,6 +86,39 @@ Environment="ETCD_PEER_BIND_ADDR=127.0.0.1:7002"
 	}
 }
 
+func TestEtcdEnvironmentWrittenToDiskDefaultToMachineID(t *testing.T) {
+	ec := EtcdEnvironment{}
+	dir, err := ioutil.TempDir(os.TempDir(), "coreos-cloudinit-")
+	if err != nil {
+		t.Fatalf("Unable to create tempdir: %v", err)
+	}
+	defer syscall.Rmdir(dir)
+
+	os.Mkdir(path.Join(dir, "etc"), os.FileMode(0755))
+	err = ioutil.WriteFile(path.Join(dir, "etc", "machine-id"), []byte("node007"), os.FileMode(0444))
+	if err != nil {
+		t.Fatalf("Failed writing out /etc/machine-id: %v", err)
+	}
+
+	if err := WriteEtcdEnvironment(ec, dir); err != nil {
+		t.Fatalf("Processing of EtcdEnvironment failed: %v", err)
+	}
+
+	fullPath := path.Join(dir, "run", "systemd", "system", "etcd.service.d", "20-cloudinit.conf")
+
+	contents, err := ioutil.ReadFile(fullPath)
+	if err != nil {
+		t.Fatalf("Unable to read expected file: %v", err)
+	}
+
+	expect := `[Service]
+Environment="ETCD_NAME=node007"
+`
+	if string(contents) != expect {
+		t.Fatalf("File has incorrect contents")
+	}
+}
+
 func rmdir(path string) error {
     cmd := exec.Command("rm", "-rf", path)
     return cmd.Run()

system/systemd.go

@@ -2,6 +2,7 @@ package system
 
 import (
 	"fmt"
+	"io/ioutil"
 	"log"
 	"os"
 	"os/exec"
@@ -12,6 +13,10 @@ import (
 	"github.com/coreos/coreos-cloudinit/third_party/github.com/coreos/go-systemd/dbus"
 )
 
+// fakeMachineID is placed on non-usr CoreOS images and should
+// never be used as a true MachineID
+const fakeMachineID = "42000000000000000000000000000042"
+
 type Unit struct {
 	Name    string
 	Runtime bool
@@ -161,3 +166,18 @@ func ExecuteScript(scriptPath string) (string, error) {
 func SetHostname(hostname string) error {
 	return exec.Command("hostnamectl", "set-hostname", hostname).Run()
 }
+
+func Hostname() (string, error) {
+	return os.Hostname()
+}
+
+func MachineID(root string) string {
+	contents, _ := ioutil.ReadFile(path.Join(root, "etc", "machine-id"))
+	id := strings.TrimSpace(string(contents))
+
+	if id == fakeMachineID {
+		id = ""
+	}
+
+	return id
+}

system/systemd_test.go

@@ -100,3 +100,17 @@ Where=/media/state
 	}
 }
 
+func TestMachineID(t *testing.T) {
+	dir, err := ioutil.TempDir(os.TempDir(), "coreos-cloudinit-")
+	if err != nil {
+		t.Fatalf("Unable to create tempdir: %v", err)
+	}
+	defer syscall.Rmdir(dir)
+
+	os.Mkdir(path.Join(dir, "etc"), os.FileMode(0755))
+	ioutil.WriteFile(path.Join(dir, "etc", "machine-id"), []byte("node007\n"), os.FileMode(0444))
+
+	if MachineID(dir) != "node007" {
+		t.Fatalf("File has incorrect contents")
+	}
+}

test.yaml

@@ -1,7 +0,0 @@
-#cloud-config
-
-coreos:
-    etcd:
-        discovery_url: https://discovery.etcd.io/0022cb5027f8f5167a874794c3a13e0d
-        bind-addr: $public_ipv4:4001
-        name: polvi