Initial public commit of mgmt

This is a prototype that i'm attempting to "release early". Expect a lot
of changes! It is intended to be a config management tool that will:

* be event based
* execute actions in parallel
* function as a distributed system

There are a bunch more design ideas going into this, please stay tuned!

main.go

@@ -0,0 +1,147 @@
+// Mgmt
+// Copyright (C) 2013-2015+ James Shubin and the project contributors
+// Written by James Shubin <james@shubin.ca> and the project contributors
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package main
+
+import (
+	"fmt"
+	"github.com/codegangsta/cli"
+	"log"
+	"os"
+	"os/signal"
+	"sync"
+	"syscall"
+	"time"
+)
+
+// set at compile time
+var (
+	version string
+	program string
+)
+
+const (
+	DEBUG = false
+)
+
+// signal handler
+func waitForSignal(exit chan bool) {
+	signals := make(chan os.Signal, 1)
+	signal.Notify(signals, os.Interrupt) // catch ^C
+	//signal.Notify(signals, os.Kill) // catch signals
+	signal.Notify(signals, syscall.SIGTERM)
+
+	select {
+	case e := <-signals: // any signal will do
+		if e == os.Interrupt {
+			fmt.Println() // put ^C char from terminal on its own line
+			log.Println("Interrupted by ^C")
+		} else {
+			log.Println("Interrupted by signal")
+		}
+	case <-exit: // or a manual signal
+		log.Println("Interrupted by exit signal")
+	}
+}
+
+func run(c *cli.Context) {
+	var start int64 = time.Now().UnixNano()
+	var wg sync.WaitGroup
+	exit := make(chan bool) // exit signal
+	log.Printf("This is: %v, version: %v\n", program, version)
+
+	// exit after `exittime` seconds for no reason at all...
+	if i := c.Int("exittime"); i > 0 {
+		go func() {
+			time.Sleep(time.Duration(i) * time.Second)
+			exit <- true
+		}()
+	}
+
+	// build the graph from a config file
+	G := GraphFromConfig(c.String("file"))
+	log.Printf("Graph: %v\n", G) // show graph
+
+	log.Printf("Start: %v\n", start)
+
+	for x := range G.GetVerticesChan() { // XXX ?
+		log.Printf("Main->Starting[%v]\n", x.Name)
+
+		wg.Add(1)
+		// must pass in value to avoid races...
+		// see: https://ttboj.wordpress.com/2015/07/27/golang-parallelism-issues-causing-too-many-open-files-error/
+		go func(v *Vertex) {
+			defer wg.Done()
+			v.Start()
+			log.Printf("Main->Finish[%v]\n", v.Name)
+		}(x)
+
+		// generate a startup "poke" so that an initial check happens
+		go func(v *Vertex) {
+			v.Events <- fmt.Sprintf("Startup(%v)", v.Name)
+		}(x)
+	}
+
+	log.Println("Running...")
+
+	waitForSignal(exit) // pass in exit channel to watch
+
+	G.Exit() // tell all the children to exit
+
+	if DEBUG {
+		for i := range G.GetVerticesChan() {
+			fmt.Printf("Vertex: %v\n", i)
+		}
+		fmt.Printf("Graph: %v\n", G)
+	}
+
+	wg.Wait() // wait for primary go routines to exit
+
+	// TODO: wait for each vertex to exit...
+	log.Println("Goodbye!")
+}
+
+func main() {
+	app := cli.NewApp()
+	app.Name = program
+	app.Usage = "next generation config management"
+	app.Version = version
+	//app.Action = ... // without a default action, help runs
+
+	app.Commands = []cli.Command{
+		{
+			Name:    "run",
+			Aliases: []string{"r"},
+			Usage:   "run",
+			Action:  run,
+			Flags: []cli.Flag{
+				cli.StringFlag{
+					Name:  "file, f",
+					Value: "",
+					Usage: "graph definition to run",
+				},
+				cli.IntFlag{
+					Name:  "exittime",
+					Value: 0,
+					Usage: "exit after a maximum of approximately this many seconds",
+				},
+			},
+		},
+	}
+	app.EnableBashCompletion = true
+	app.Run(os.Args)
+}