[WIP] K8s update and runtime package changes (#895)

* First commit: outline of K8s runtime package

* Added poller. Added auto-updater into default runtime

* Added build and updated Poller interface

* Added comments and NewRuntime that accepts Options

* DefaultPoller; Runtime options

* First commit to add Kubernetes cruft

* Add comments

* Add micro- prefix to K8s runtime service names

* Get rid of import cycles. Move K8s runtime into main runtime package

* Major refactoring: Poller replaced by Notifier

POller has been replaced by Notifier which returns a channel of events
that can be consumed and acted upon.

* Added runtime configuration options

* K8s runtime is now Kubernetes runtime in dedicated pkg. Naming kung-fu.

* Fix typo in command.

* Fixed typo

* Dont Delete service when runtime stops.

runtime.Stop stops services; no need to double-stop

* Track runtime services

* Parse Unix timestamps properly

* Added deployments into K8s client. Debug logging

runtime/service.go

@@ -0,0 +1,158 @@
+package runtime
+
+import (
+	"io"
+	"strings"
+	"sync"
+
+	packager "github.com/micro/go-micro/runtime/package"
+	"github.com/micro/go-micro/runtime/process"
+	proc "github.com/micro/go-micro/runtime/process/os"
+	"github.com/micro/go-micro/util/log"
+)
+
+type service struct {
+	sync.RWMutex
+
+	running bool
+	closed  chan bool
+	err     error
+
+	// output for logs
+	output io.Writer
+
+	// service to manage
+	*Service
+	// process creator
+	Process *proc.Process
+	// Exec
+	Exec *process.Executable
+	// process pid
+	PID *process.PID
+}
+
+func newService(s *Service, c CreateOptions) *service {
+	var exec string
+	var args []string
+
+	if len(s.Exec) > 0 {
+		parts := strings.Split(s.Exec, " ")
+		exec = parts[0]
+		args = []string{}
+
+		if len(parts) > 1 {
+			args = parts[1:]
+		}
+	} else {
+		// set command
+		exec = c.Command[0]
+		// set args
+		if len(c.Command) > 1 {
+			args = c.Command[1:]
+		}
+	}
+
+	return &service{
+		Service: s,
+		Process: new(proc.Process),
+		Exec: &process.Executable{
+			Binary: &packager.Binary{
+				Name: s.Name,
+				Path: exec,
+			},
+			Env:  c.Env,
+			Args: args,
+		},
+		closed: make(chan bool),
+		output: c.Output,
+	}
+}
+
+func (s *service) streamOutput() {
+	go io.Copy(s.output, s.PID.Output)
+	go io.Copy(s.output, s.PID.Error)
+}
+
+// Running returns true is the service is running
+func (s *service) Running() bool {
+	s.RLock()
+	defer s.RUnlock()
+	return s.running
+}
+
+// Start stars the service
+func (s *service) Start() error {
+	s.Lock()
+	defer s.Unlock()
+
+	if s.running {
+		return nil
+	}
+
+	// reset
+	s.err = nil
+	s.closed = make(chan bool)
+
+	// TODO: pull source & build binary
+	log.Debugf("Runtime service %s forking new process", s.Service.Name)
+	p, err := s.Process.Fork(s.Exec)
+	if err != nil {
+		return err
+	}
+
+	// set the pid
+	s.PID = p
+	// set to running
+	s.running = true
+
+	if s.output != nil {
+		s.streamOutput()
+	}
+
+	// wait and watch
+	go s.Wait()
+
+	return nil
+}
+
+// Stop stops the service
+func (s *service) Stop() error {
+	s.Lock()
+	defer s.Unlock()
+
+	select {
+	case <-s.closed:
+		return nil
+	default:
+		close(s.closed)
+		s.running = false
+		if s.PID == nil {
+			return nil
+		}
+		return s.Process.Kill(s.PID)
+	}
+}
+
+// Error returns the last error service has returned
+func (s *service) Error() error {
+	s.RLock()
+	defer s.RUnlock()
+	return s.err
+}
+
+// Wait waits for the service to finish running
+func (s *service) Wait() {
+	// wait for process to exit
+	err := s.Process.Wait(s.PID)
+
+	s.Lock()
+	defer s.Unlock()
+
+	// save the error
+	if err != nil {
+		s.err = err
+	}
+
+	// no longer running
+	s.running = false
+}