kpod attach

Attach to a running container

Signed-off-by: baude <bbaude@redhat.com>

Closes: #95
Approved by: rhatdan

2 files changed, 87 insertions, 0 deletions

diff --git a/cmd/kpod/attach.go b/cmd/kpod/attach.go
new file mode 100644
index 000000000..d319ff70d
--- /dev/null
+++ b/cmd/kpod/attach.go
@@ -0,0 +1,86 @@
+package main
+
+import (
+	"sync"
+
+	"github.com/pkg/errors"
+	"github.com/projectatomic/libpod/libpod"
+	"github.com/sirupsen/logrus"
+	"github.com/urfave/cli"
+)
+
+var (
+	attachFlags = []cli.Flag{
+		cli.StringFlag{
+			Name:  "detach-keys",
+			Usage: "Override the key sequence for detaching a container. Format is a single character [a-Z] or ctrl-<value> where <value> is one of: a-z, @, ^, [, , or _.",
+		},
+		cli.BoolFlag{
+			Name:  "no-stdin",
+			Usage: "Do not attach STDIN. The default is false.",
+		},
+	}
+	attachDescription = "The kpod attach command allows you to attach to a running container using the container's ID or name, either to view its ongoing output or to control it interactively."
+	attachCommand     = cli.Command{
+		Name:        "attach",
+		Usage:       "Attach to a running container",
+		Description: attachDescription,
+		Flags:       attachFlags,
+		Action:      attachCmd,
+		ArgsUsage:   "",
+	}
+)
+
+func attachCmd(c *cli.Context) error {
+	args := c.Args()
+	if err := validateFlags(c, attachFlags); err != nil {
+		return err
+	}
+
+	if len(c.Args()) < 1 || len(c.Args()) > 1 {
+		return errors.Errorf("attach requires the name or id of one running container")
+	}
+
+	runtime, err := getRuntime(c)
+	if err != nil {
+		return errors.Wrapf(err, "error creating libpod runtime")
+	}
+	defer runtime.Shutdown(false)
+
+	ctr, err := runtime.LookupContainer(args[0])
+
+	if err != nil {
+		return errors.Wrapf(err, "unable to exec into %s", args[0])
+	}
+
+	conState, err := ctr.State()
+	if err != nil {
+		return errors.Wrapf(err, "unable to determine state of %s", args[0])
+	}
+	if conState != libpod.ContainerStateRunning {
+		return errors.Errorf("you can only attach to running containers")
+	}
+	// Create a bool channel to track that the console socket attach
+	// is successful.
+	attached := make(chan bool)
+	// Create a waitgroup so we can sync and wait for all goroutines
+	// to finish before exiting main
+	var wg sync.WaitGroup
+
+	// We increment the wg counter because we need to do the attach
+	wg.Add(1)
+	// Attach to the running container
+	go func() {
+		logrus.Debug("trying to attach to the container %s", ctr.ID())
+		defer wg.Done()
+		if err := ctr.Attach(c.Bool("no-stdin"), c.String("detach-keys"), attached); err != nil {
+			logrus.Errorf("unable to attach to container %s: %q", ctr.ID(), err)
+		}
+	}()
+	if !<-attached {
+		return errors.Errorf("unable to attach to container %s", ctr.ID())
+	}
+	wg.Wait()
+
+	return nil
+}
diff --git a/cmd/kpod/main.go b/cmd/kpod/main.go
index a4bb12475..dfa57d689 100644
--- a/cmd/kpod/main.go
+++ b/cmd/kpod/main.go
@@ -34,6 +34,7 @@ func main() {
 	app.Version = v
 
 	app.Commands = []cli.Command{
+		attachCommand,
 		createCommand,
 		diffCommand,
 		exportCommand,