Add support for multiple executor backends. Create Executor interface and allow executors to register themselves with the application. Update README (Todo list).

executors/abstract.go

@@ -0,0 +1,47 @@
+package executors
+
+import (
+	"fmt"
+)
+
+type Job struct {
+	Command       []string
+	Args          []string
+}
+
+type Executor interface {
+	Start() error
+	Stop() error
+	WaitForState(ExecutorPhase) error
+	String() string
+}
+
+type AbstractExecutor struct {
+	Job        Job
+}
+
+type ExecutorPhase string
+
+const (
+	ExecutorPreparing    ExecutorPhase = "Preparing"
+	ExecutorRunning      ExecutorPhase = "Running"
+	ExecutorSucceeded    ExecutorPhase = "Succeeded"
+	ExecutorFailed       ExecutorPhase = "Failed"
+	ExecutorUnknown      ExecutorPhase = "Unknown"
+)
+
+func (e *AbstractExecutor) Start() error {
+	return nil
+}
+
+func (e *AbstractExecutor) Stop() error {
+	return nil
+}
+
+func (e *AbstractExecutor) WaitForState(p ExecutorPhase) error {
+	return nil
+}
+
+func (e *AbstractExecutor) String() string {
+	return fmt.Sprintf("%s %s", e.Job.Command, e.Job.Args)
+}