Shortcut for most recent container

It is desirable to have a shortcut for the most
recently created container.  We can now use "**latest"
to represent the most recent container instead of its
container ID or name.  For example:

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

Closes: #179
Approved by: baude

11 files changed, 144 insertions, 38 deletions

diff --git a/cmd/podman/attach.go b/cmd/podman/attach.go
index 8c2c99fd5..e468964f6 100644
--- a/cmd/podman/attach.go
+++ b/cmd/podman/attach.go
@@ -19,6 +19,7 @@ var (
 			Name:  "no-stdin",
 			Usage: "Do not attach STDIN. The default is false.",
 		},
+		LatestFlag,
 	}
 	attachDescription = "The podman 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{
@@ -33,12 +34,12 @@ var (
 
 func attachCmd(c *cli.Context) error {
 	args := c.Args()
+	var ctr *libpod.Container
 	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")
+	if len(c.Args()) > 1 || (len(c.Args()) == 0 && !c.Bool("latest")) {
+		return errors.Errorf("attach requires the name or id of one running container or the latest flag")
 	}
 
 	runtime, err := getRuntime(c)
@@ -47,7 +48,11 @@ func attachCmd(c *cli.Context) error {
 	}
 	defer runtime.Shutdown(false)
 
-	ctr, err := runtime.LookupContainer(args[0])
+	if c.Bool("latest") {
+		ctr, err = runtime.GetLatestContainer()
+	} else {
+		ctr, err = runtime.LookupContainer(args[0])
+	}
 
 	if err != nil {
 		return errors.Wrapf(err, "unable to exec into %s", args[0])
diff --git a/cmd/podman/common.go b/cmd/podman/common.go
index 5e670dcc8..e3997539a 100644
--- a/cmd/podman/common.go
+++ b/cmd/podman/common.go
@@ -14,6 +14,14 @@ import (
 	"github.com/urfave/cli"
 )
 
+var (
+	stores     = make(map[storage.Store]struct{})
+	LatestFlag = cli.BoolFlag{
+		Name:  "latest, l",
+		Usage: "act on the latest container podman is aware of",
+	}
+)
+
 const crioConfigPath = "/etc/crio/crio.conf"
 
 func getRuntime(c *cli.Context) (*libpod.Runtime, error) {
diff --git a/cmd/podman/exec.go b/cmd/podman/exec.go
index 7a0bab617..07ef3a0cd 100644
--- a/cmd/podman/exec.go
+++ b/cmd/podman/exec.go
@@ -27,6 +27,7 @@ var (
 			Name:  "user, u",
 			Usage: "Sets the username or UID used and optionally the groupname or GID for the specified command",
 		},
+		LatestFlag,
 	}
 	execDescription = `
 	podman exec
@@ -48,20 +49,30 @@ var (
 func execCmd(c *cli.Context) error {
 	var envs []string
 	args := c.Args()
-	if len(args) < 1 {
+	var ctr *libpod.Container
+	var err error
+	argStart := 1
+	if len(args) < 1 && !c.Bool("latest") {
 		return errors.Errorf("you must provide one container name or id")
 	}
-	if len(args) < 2 {
+	if len(args) < 2 && !c.Bool("latest") {
 		return errors.Errorf("you must provide a command to exec")
 	}
-	cmd := args[1:]
+	if c.Bool("latest") {
+		argStart = 0
+	}
+	cmd := args[argStart:]
 	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 c.Bool("latest") {
+		ctr, err = runtime.GetLatestContainer()
+	} else {
+		ctr, err = runtime.LookupContainer(args[0])
+	}
 	if err != nil {
 		return errors.Wrapf(err, "unable to exec into %s", args[0])
 	}
diff --git a/cmd/podman/inspect.go b/cmd/podman/inspect.go
index 869d16911..dc5810492 100644
--- a/cmd/podman/inspect.go
+++ b/cmd/podman/inspect.go
@@ -33,6 +33,7 @@ var (
 			Name:  "size",
 			Usage: "Display total file size if the type is container",
 		},
+		LatestFlag,
 	}
 	inspectDescription = "This displays the low-level information on containers and images identified by name or ID. By default, this will render all results in a JSON array. If the container and image have the same name, this will return container JSON for unspecified type."
 	inspectCommand     = cli.Command{
@@ -47,7 +48,10 @@ var (
 
 func inspectCmd(c *cli.Context) error {
 	args := c.Args()
-	if len(args) == 0 {
+	inspectType := c.String("type")
+	latestContainer := c.Bool("latest")
+	var name string
+	if len(args) == 0 && !latestContainer {
 		return errors.Errorf("container or image name must be specified: podman inspect [options [...]] name")
 	}
 	if len(args) > 1 {
@@ -63,17 +67,26 @@ func inspectCmd(c *cli.Context) error {
 	}
 	defer runtime.Shutdown(false)
 
-	if c.String("type") != inspectTypeContainer && c.String("type") != inspectTypeImage && c.String("type") != inspectAll {
+	if !libpod.StringInSlice(inspectType, []string{inspectTypeContainer, inspectTypeImage, inspectAll}) {
 		return errors.Errorf("the only recognized types are %q, %q, and %q", inspectTypeContainer, inspectTypeImage, inspectAll)
 	}
-
-	name := args[0]
-
+	if !latestContainer {
+		name = args[0]
+	}
+	if latestContainer {
+		inspectType = inspectTypeContainer
+	}
 	outputFormat := c.String("format")
 	var data interface{}
-	switch c.String("type") {
+	switch inspectType {
 	case inspectTypeContainer:
-		ctr, err := runtime.LookupContainer(name)
+		var ctr *libpod.Container
+		var err error
+		if latestContainer {
+			ctr, err = runtime.GetLatestContainer()
+		} else {
+			ctr, err = runtime.LookupContainer(name)
+		}
 		if err != nil {
 			return errors.Wrapf(err, "error looking up container %q", name)
 		}
diff --git a/cmd/podman/kill.go b/cmd/podman/kill.go
index 776c7ef20..c24e68c54 100644
--- a/cmd/podman/kill.go
+++ b/cmd/podman/kill.go
@@ -1,10 +1,10 @@
 package main
 
 import (
-	"fmt"
 	"os"
 	"syscall"
 
+	"fmt"
 	"github.com/docker/docker/pkg/signal"
 	"github.com/pkg/errors"
 	"github.com/urfave/cli"
@@ -17,24 +17,29 @@ var (
 			Usage: "Signal to send to the container",
 			Value: "KILL",
 		},
+		LatestFlag,
 	}
 	killDescription = "The main process inside each container specified will be sent SIGKILL, or any signal specified with option --signal."
 	killCommand     = cli.Command{
-		Name:        "kill",
-		Usage:       "Kill one or more running containers with a specific signal",
-		Description: killDescription,
-		Flags:       killFlags,
-		Action:      killCmd,
-		ArgsUsage:   "[CONTAINER_NAME_OR_ID]",
+		Name:                   "kill",
+		Usage:                  "Kill one or more running containers with a specific signal",
+		Description:            killDescription,
+		Flags:                  killFlags,
+		Action:                 killCmd,
+		ArgsUsage:              "[CONTAINER_NAME_OR_ID]",
+		UseShortOptionHandling: true,
 	}
 )
 
 // killCmd kills one or more containers with a signal
 func killCmd(c *cli.Context) error {
 	args := c.Args()
-	if len(args) == 0 {
+	if len(args) == 0 && !c.Bool("latest") {
 		return errors.Errorf("specify one or more containers to kill")
 	}
+	if len(args) > 0 && c.Bool("latest") {
+		return errors.Errorf("you cannot specific any containers to kill with --latest")
+	}
 	if err := validateFlags(c, killFlags); err != nil {
 		return err
 	}
@@ -56,8 +61,16 @@ func killCmd(c *cli.Context) error {
 		killSignal = uint(sysSignal)
 	}
 
+	if c.Bool("latest") {
+		latestCtr, err := runtime.GetLatestContainer()
+		if err != nil {
+			return errors.Wrapf(err, "unable to get latest container")
+		}
+		args = append(args, latestCtr.ID())
+	}
+
 	var lastError error
-	for _, container := range c.Args() {
+	for _, container := range args {
 		ctr, err := runtime.LookupContainer(container)
 		if err != nil {
 			if lastError != nil {
diff --git a/cmd/podman/logs.go b/cmd/podman/logs.go
index 8745d5d7f..b31dce2d3 100644
--- a/cmd/podman/logs.go
+++ b/cmd/podman/logs.go
@@ -37,6 +37,7 @@ var (
 			Name:  "tail",
 			Usage: "Output the specified number of LINES at the end of the logs.  Defaults to 0, which prints all lines",
 		},
+		LatestFlag,
 	}
 	logsDescription = "The podman 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 podman run (i.e. your run may not have generated any logs at the time you execute podman logs"
@@ -51,6 +52,8 @@ var (
 )
 
 func logsCmd(c *cli.Context) error {
+	var ctr *libpod.Container
+	var err error
 	if err := validateFlags(c, logsFlags); err != nil {
 		return err
 	}
@@ -62,7 +65,7 @@ func logsCmd(c *cli.Context) error {
 	defer runtime.Shutdown(false)
 
 	args := c.Args()
-	if len(args) != 1 {
+	if len(args) != 1 && !c.Bool("latest") {
 		return errors.Errorf("'podman logs' requires exactly one container name/ID")
 	}
 
@@ -83,7 +86,11 @@ func logsCmd(c *cli.Context) error {
 		tail:      c.Uint64("tail"),
 	}
 
-	ctr, err := runtime.LookupContainer(args[0])
+	if c.Bool("latest") {
+		ctr, err = runtime.GetLatestContainer()
+	} else {
+		ctr, err = runtime.LookupContainer(args[0])
+	}
 	if err != nil {
 		return err
 	}
diff --git a/cmd/podman/rm.go b/cmd/podman/rm.go
index dcb8fac57..8dd3475c0 100644
--- a/cmd/podman/rm.go
+++ b/cmd/podman/rm.go
@@ -19,6 +19,7 @@ var (
 			Name:  "all, a",
 			Usage: "Remove all containers",
 		},
+		LatestFlag,
 	}
 	rmDescription = "Remove one or more containers"
 	rmCommand     = cli.Command{
@@ -46,7 +47,11 @@ func rmCmd(c *cli.Context) error {
 	defer runtime.Shutdown(false)
 
 	args := c.Args()
-	if len(args) == 0 && !c.Bool("all") {
+	if c.Bool("latest") && c.Bool("all") {
+		return errors.Errorf("--all and --latest cannot be used together")
+	}
+
+	if len(args) == 0 && !c.Bool("all") && !c.Bool("latest") {
 		return errors.Errorf("specify one or more containers to remove")
 	}
 
@@ -57,6 +62,12 @@ func rmCmd(c *cli.Context) error {
 		if err != nil {
 			return errors.Wrapf(err, "unable to get container list")
 		}
+	} else if c.Bool("latest") {
+		lastCtr, err := runtime.GetLatestContainer()
+		if err != nil {
+			return errors.Wrapf(err, "unable to get latest container")
+		}
+		delContainers = append(delContainers, lastCtr)
 	} else {
 		for _, i := range args {
 			container, err := runtime.LookupContainer(i)
diff --git a/cmd/podman/start.go b/cmd/podman/start.go
index d4ddfbbe7..0dad5e237 100644
--- a/cmd/podman/start.go
+++ b/cmd/podman/start.go
@@ -26,6 +26,7 @@ var (
 			Name:  "interactive, i",
 			Usage: "Keep STDIN open even if not attached",
 		},
+		LatestFlag,
 	}
 	startDescription = `
    podman start
@@ -46,7 +47,7 @@ var (
 
 func startCmd(c *cli.Context) error {
 	args := c.Args()
-	if len(args) < 1 {
+	if len(args) < 1 && !c.Bool("latest") {
 		return errors.Errorf("you must provide at least one container name or id")
 	}
 
@@ -65,7 +66,13 @@ func startCmd(c *cli.Context) error {
 		return errors.Wrapf(err, "error creating libpod runtime")
 	}
 	defer runtime.Shutdown(false)
-
+	if c.Bool("latest") {
+		lastCtr, err := runtime.GetLatestContainer()
+		if err != nil {
+			return errors.Wrapf(err, "unable to get latest container")
+		}
+		args = append(args, lastCtr.ID())
+	}
 	var lastError error
 	for _, container := range args {
 		// Create a bool channel to track that the console socket attach
diff --git a/cmd/podman/stats.go b/cmd/podman/stats.go
index cf54a8bfe..d2ffd8a75 100644
--- a/cmd/podman/stats.go
+++ b/cmd/podman/stats.go
@@ -42,7 +42,7 @@ var (
 		cli.BoolFlag{
 			Name:  "no-reset",
 			Usage: "disable resetting the screen between intervals",
-		},
+		}, LatestFlag,
 	}
 
 	statsDescription = "display a live stream of one or more containers' resource usage statistics"
@@ -61,6 +61,15 @@ func statsCmd(c *cli.Context) error {
 		return err
 	}
 
+	all := c.Bool("all")
+
+	if c.Bool("latest") && all {
+		return errors.Errorf("--all and --latest cannot be used together")
+	}
+
+	if c.Bool("latest") && len(c.Args()) > 0 {
+		return errors.Errorf("no container names are allowed with --latest")
+	}
 	runtime, err := getRuntime(c)
 	if err != nil {
 		return errors.Wrapf(err, "could not get runtime")
@@ -75,7 +84,6 @@ func statsCmd(c *cli.Context) error {
 	var format string
 	var ctrs []*libpod.Container
 	var containerFunc func() ([]*libpod.Container, error)
-	all := c.Bool("all")
 
 	if c.IsSet("format") {
 		format = c.String("format")
@@ -85,6 +93,13 @@ func statsCmd(c *cli.Context) error {
 
 	if len(c.Args()) > 0 {
 		containerFunc = func() ([]*libpod.Container, error) { return runtime.GetContainersByList(c.Args()) }
+	} else if c.Bool("latest") {
+		containerFunc = func() ([]*libpod.Container, error) {
+			var ctrs []*libpod.Container
+			lastCtr, err := runtime.GetLatestContainer()
+			ctrs = append(ctrs, lastCtr)
+			return ctrs, err
+		}
 	} else if all {
 		containerFunc = runtime.GetAllContainers
 	} else {
diff --git a/cmd/podman/stop.go b/cmd/podman/stop.go
index f85512d47..d18a05bd4 100644
--- a/cmd/podman/stop.go
+++ b/cmd/podman/stop.go
@@ -19,7 +19,7 @@ var (
 		cli.BoolFlag{
 			Name:  "all, a",
 			Usage: "stop all running containers",
-		},
+		}, LatestFlag,
 	}
 	stopDescription = `
    podman stop
@@ -41,10 +41,13 @@ var (
 
 func stopCmd(c *cli.Context) error {
 	args := c.Args()
-	if c.Bool("all") && len(args) > 0 {
-		return errors.Errorf("no arguments are needed with -a")
+	if (c.Bool("all") || c.Bool("latest")) && len(args) > 0 {
+		return errors.Errorf("no arguments are needed with --all or --latest")
+	}
+	if c.Bool("all") && c.Bool("latest") {
+		return errors.Errorf("--all and --latest cannot be used together")
 	}
-	if len(args) < 1 && !c.Bool("all") {
+	if len(args) < 1 && !c.Bool("all") && !c.Bool("latest") {
 		return errors.Errorf("you must provide at least one container name or id")
 	}
 	if err := validateFlags(c, stopFlags); err != nil {
@@ -71,6 +74,12 @@ func stopCmd(c *cli.Context) error {
 		if err != nil {
 			return errors.Wrapf(err, "unable to get running containers")
 		}
+	} else if c.Bool("latest") {
+		lastCtr, err := runtime.GetLatestContainer()
+		if err != nil {
+			return errors.Wrapf(err, "unable to get last created container")
+		}
+		containers = append(containers, lastCtr)
 	} else {
 		for _, i := range args {
 			container, err := runtime.LookupContainer(i)
diff --git a/cmd/podman/top.go b/cmd/podman/top.go
index 796b31c1d..5b1dbd05c 100644
--- a/cmd/podman/top.go
+++ b/cmd/podman/top.go
@@ -16,7 +16,7 @@ var (
 		cli.StringFlag{
 			Name:  "format",
 			Usage: "Change the output to JSON",
-		},
+		}, LatestFlag,
 	}
 	topDescription = `
    podman top
@@ -36,6 +36,8 @@ var (
 )
 
 func topCmd(c *cli.Context) error {
+	var container *libpod.Container
+	var err error
 	doJSON := false
 	if c.IsSet("format") {
 		if strings.ToUpper(c.String("format")) == "JSON" {
@@ -47,7 +49,7 @@ func topCmd(c *cli.Context) error {
 	args := c.Args()
 	var psArgs []string
 	psOpts := []string{"-o", "uid,pid,ppid,c,stime,tname,time,cmd"}
-	if len(args) < 1 {
+	if len(args) < 1 && !c.Bool("latest") {
 		return errors.Errorf("you must provide the name or id of a running container")
 	}
 	if err := validateFlags(c, topFlags); err != nil {
@@ -63,7 +65,12 @@ func topCmd(c *cli.Context) error {
 		psOpts = args[1:]
 	}
 
-	container, err := runtime.LookupContainer(args[0])
+	if c.Bool("latest") {
+		container, err = runtime.GetLatestContainer()
+	} else {
+		container, err = runtime.LookupContainer(args[0])
+	}
+
 	if err != nil {
 		return errors.Wrapf(err, "unable to lookup %s", args[0])
 	}