Rework exec to enable splitting to retrieve exec PID

Signed-off-by: Matthew Heon <matthew.heon@gmail.com>

Closes: #412
Approved by: baude

libpod/container_api.go

@@ -2,13 +2,11 @@ package libpod
 
 import (
 	"encoding/json"
-	"fmt"
 	"io/ioutil"
 	"os"
 	"path/filepath"
 
 	"github.com/docker/docker/daemon/caps"
-	"github.com/docker/docker/pkg/stringid"
 	"github.com/docker/docker/pkg/term"
 	"github.com/pkg/errors"
 	"github.com/projectatomic/libpod/libpod/driver"
@@ -236,21 +234,8 @@ func (c *Container) Exec(tty, privileged bool, env, cmd []string, user string) e
 	if privileged || c.config.Privileged {
 		capList = caps.GetAllCapabilities()
 	}
-	globalOpts := runcGlobalOptions{
-		log: c.LogPath(),
-	}
 
-	execOpts := runcExecOptions{
-		capAdd:     capList,
-		pidFile:    filepath.Join(c.state.RunDir, fmt.Sprintf("%s-execpid", stringid.GenerateNonCryptoID()[:12])),
-		env:        env,
-		noNewPrivs: c.config.Spec.Process.NoNewPrivileges,
-		user:       user,
-		cwd:        c.config.Spec.Process.Cwd,
-		tty:        tty,
-	}
-
-	return c.runtime.ociRuntime.execContainer(c, cmd, globalOpts, execOpts)
+	return c.runtime.ociRuntime.execContainer(c, cmd, tty, user, capList, env)
 }
 
 // Attach attaches to a container

libpod/oci.go

@@ -467,8 +467,54 @@ func (r *OCIRuntime) unpauseContainer(ctr *Container) error {
 	return utils.ExecCmdWithStdStreams(os.Stdin, os.Stdout, os.Stderr, r.path, "resume", ctr.ID())
 }
 
-//execContiner executes a command in a running container
-func (r *OCIRuntime) execContainer(c *Container, cmd []string, globalOpts runcGlobalOptions, commandOpts runcExecOptions) error {
-	r.RuncExec(c, cmd, globalOpts, commandOpts)
-	return nil
+// execContainer executes a command in a running container
+// TODO: Add --detach support
+// TODO: Convert to use conmon
+// TODO: add --pid-file and use that to generate exec session tracking
+func (r *OCIRuntime) execContainer(c *Container, cmd []string, tty bool, user string, capAdd, env []string) error {
+	args := []string{}
+
+	// TODO - should we maintain separate logpaths for exec sessions?
+	args = append(args, "--log", c.LogPath())
+
+	args = append(args, "exec")
+
+	args = append(args, "--cwd", c.config.Spec.Process.Cwd)
+
+	if tty {
+		args = append(args, "--tty")
+	}
+
+	if user != "" {
+		args = append(args, "--user", user)
+	}
+
+	if c.config.Spec.Process.NoNewPrivileges {
+		args = append(args, "--no-new-privs")
+	}
+
+	for _, cap := range capAdd {
+		args = append(args, "--cap", cap)
+	}
+
+	for _, envVar := range env {
+		args = append(args, "--env", envVar)
+	}
+
+	// Append container ID and command
+	args = append(args, c.ID())
+	args = append(args, cmd...)
+
+	logrus.Debugf("Starting runtime %s with following arguments: %v", r.path, args)
+
+	execCmd := exec.Command(r.path, args...)
+	execCmd.Stdout = os.Stdout
+	execCmd.Stderr = os.Stderr
+	execCmd.Stdin = os.Stdin
+
+	if err := execCmd.Start(); err != nil {
+		return errors.Wrapf(err, "error starting exec command for container %s", c.ID())
+	}
+
+	return execCmd.Wait()
 }