Add kpod logs command

Signed-off-by: Ryan Cole <rcyoalne@gmail.com>

cmd/kpod/logs.go

@@ -0,0 +1,88 @@
+package main
+
+import (
+	"fmt"
+	"time"
+
+	"github.com/kubernetes-incubator/cri-o/libkpod"
+	"github.com/pkg/errors"
+	"github.com/urfave/cli"
+)
+
+var (
+	logsFlags = []cli.Flag{
+		cli.BoolFlag{
+			Name:   "details",
+			Usage:  "Show extra details provided to the logs",
+			Hidden: true,
+		},
+		cli.BoolFlag{
+			Name:  "follow, f",
+			Usage: "Follow log output.  The default is false",
+		},
+		cli.StringFlag{
+			Name:  "since",
+			Usage: "Show logs since TIMESTAMP",
+		},
+		cli.Uint64Flag{
+			Name:  "tail",
+			Usage: "Output the specified number of LINES at the end of the logs.  Defaults to 0, which prints all lines",
+		},
+	}
+	logsDescription = "The kpod logs command batch-retrieves whatever logs are present for a container at the time of execution.  This does not guarantee execution" +
+		"order when combined with kpod run (i.e. your run may not have generated any logs at the time you execute kpod logs"
+	logsCommand = cli.Command{
+		Name:        "logs",
+		Usage:       "Fetch the logs of a container",
+		Description: logsDescription,
+		Flags:       logsFlags,
+		Action:      logsCmd,
+		ArgsUsage:   "CONTAINER",
+	}
+)
+
+func logsCmd(c *cli.Context) error {
+	args := c.Args()
+	if len(args) != 1 {
+		return errors.Errorf("'kpod logs' requires exactly one container name/ID")
+	}
+	container := args[0]
+	var opts libkpod.LogOptions
+	opts.Details = c.Bool("details")
+	opts.Follow = c.Bool("follow")
+	opts.SinceTime = time.Time{}
+	if c.IsSet("since") {
+		// parse time, error out if something is wrong
+		since, err := time.Parse("2006-01-02T15:04:05.999999999-07:00", c.String("since"))
+		if err != nil {
+			return errors.Wrapf(err, "could not parse time: %q", c.String("since"))
+		}
+		opts.SinceTime = since
+	}
+	opts.Tail = c.Uint64("tail")
+
+	config, err := getConfig(c)
+	if err != nil {
+		return errors.Wrapf(err, "could not get config")
+	}
+	server, err := libkpod.New(config)
+	if err != nil {
+		return errors.Wrapf(err, "could not create container server")
+	}
+	err = server.Update()
+	if err != nil {
+		return errors.Wrapf(err, "could not update list of containers")
+	}
+	logs := make(chan string)
+	go func() {
+		err = server.GetLogs(container, logs, opts)
+	}()
+	printLogs(logs)
+	return err
+}
+
+func printLogs(logs chan string) {
+	for line := range logs {
+		fmt.Println(line)
+	}
+}