Add bindings for Container Exec Create + Inspect

Also adds some basic tests for these two. More tests are needed
but will have to wait for state to be finished.

Signed-off-by: Matthew Heon <matthew.heon@pm.me>

libpod/container_exec.go

@@ -231,6 +231,11 @@ func (c *Container) ExecStartAndAttach(sessionID string, streams *AttachStreams)
 		}
 	}
 
+	// Verify that we are in a good state to continue
+	if !c.ensureState(define.ContainerStateRunning) {
+		return errors.Wrapf(define.ErrCtrStateInvalid, "can only start exec sessions when their container is running")
+	}
+
 	session, ok := c.state.ExecSessions[sessionID]
 	if !ok {
 		return errors.Wrapf(define.ErrNoSuchExecSession, "container %s has no exec session with ID %s", c.ID(), sessionID)

libpod/options.go

@@ -21,6 +21,8 @@ import (
 
 var (
 	// NameRegex is a regular expression to validate container/pod names.
+	// This must NOT be changed from outside of Libpod. It should be a
+	// constant, but Go won't let us do that.
 	NameRegex = regexp.MustCompile("^[a-zA-Z0-9][a-zA-Z0-9_.-]*$")
 	// RegexError is thrown in presence of an invalid container/pod name.
 	RegexError = errors.Wrapf(define.ErrInvalidArg, "names must match [a-zA-Z0-9][a-zA-Z0-9_.-]*")

pkg/api/handlers/compat/exec.go

@@ -12,6 +12,7 @@ import (
 	"github.com/containers/libpod/pkg/api/handlers/utils"
 	"github.com/gorilla/mux"
 	"github.com/pkg/errors"
+	"github.com/sirupsen/logrus"
 )
 
 // ExecCreateHandler creates an exec session for a given container.
@@ -88,6 +89,8 @@ func ExecInspectHandler(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
+	logrus.Debugf("Inspecting exec session %s of container %s", sessionID, sessionCtr.ID())
+
 	session, err := sessionCtr.ExecSession(sessionID)
 	if err != nil {
 		utils.InternalServerError(w, errors.Wrapf(err, "error retrieving exec session %s from container %s", sessionID, sessionCtr.ID()))

pkg/bindings/containers/exec.go

@@ -0,0 +1,71 @@
+package containers
+
+import (
+	"context"
+	"net/http"
+	"strings"
+
+	"github.com/containers/libpod/libpod/define"
+	"github.com/containers/libpod/pkg/api/handlers"
+	"github.com/containers/libpod/pkg/bindings"
+	jsoniter "github.com/json-iterator/go"
+	"github.com/pkg/errors"
+	"github.com/sirupsen/logrus"
+)
+
+var json = jsoniter.ConfigCompatibleWithStandardLibrary
+
+// ExecCreate creates a new exec session in an existing container.
+// The exec session will not be started; that is done with ExecStart.
+// Returns ID of new exec session, or an error if one occurred.
+func ExecCreate(ctx context.Context, nameOrID string, config *handlers.ExecCreateConfig) (string, error) {
+	conn, err := bindings.GetClient(ctx)
+	if err != nil {
+		return "", err
+	}
+
+	if config == nil {
+		return "", errors.Errorf("must provide a configuration for exec session")
+	}
+
+	requestJSON, err := json.Marshal(config)
+	if err != nil {
+		return "", errors.Wrapf(err, "error marshalling exec config to JSON")
+	}
+	jsonReader := strings.NewReader(string(requestJSON))
+
+	resp, err := conn.DoRequest(jsonReader, http.MethodPost, "/containers/%s/exec", nil, nameOrID)
+	if err != nil {
+		return "", err
+	}
+
+	respStruct := new(handlers.ExecCreateResponse)
+	if err := resp.Process(respStruct); err != nil {
+		return "", err
+	}
+
+	return respStruct.ID, nil
+}
+
+// ExecInspect inspects an existing exec session, returning detailed information
+// about it.
+func ExecInspect(ctx context.Context, sessionID string) (*define.InspectExecSession, error) {
+	conn, err := bindings.GetClient(ctx)
+	if err != nil {
+		return nil, err
+	}
+
+	logrus.Debugf("Inspecting session ID %q", sessionID)
+
+	resp, err := conn.DoRequest(nil, http.MethodGet, "/exec/%s/json", nil, sessionID)
+	if err != nil {
+		return nil, err
+	}
+
+	respStruct := new(define.InspectExecSession)
+	if err := resp.Process(respStruct); err != nil {
+		return nil, err
+	}
+
+	return respStruct, nil
+}

pkg/bindings/test/containers_test.go

@@ -1,12 +1,12 @@
 package test_bindings
 
 import (
-	"github.com/containers/libpod/libpod/define"
 	"net/http"
 	"strconv"
 	"strings"
 	"time"
 
+	"github.com/containers/libpod/libpod/define"
 	"github.com/containers/libpod/pkg/bindings"
 	"github.com/containers/libpod/pkg/bindings/containers"
 	"github.com/containers/libpod/pkg/specgen"

pkg/bindings/test/exec_test.go

@@ -0,0 +1,77 @@
+package test_bindings
+
+import (
+	"time"
+
+	"github.com/containers/libpod/pkg/api/handlers"
+	"github.com/containers/libpod/pkg/bindings"
+	"github.com/containers/libpod/pkg/bindings/containers"
+	. "github.com/onsi/ginkgo"
+	. "github.com/onsi/gomega"
+	"github.com/onsi/gomega/gexec"
+)
+
+var _ = Describe("Podman containers exec", func() {
+	var (
+		bt *bindingTest
+		s  *gexec.Session
+	)
+
+	BeforeEach(func() {
+		bt = newBindingTest()
+		bt.RestoreImagesFromCache()
+		s = bt.startAPIService()
+		time.Sleep(1 * time.Second)
+		err := bt.NewConnection()
+		Expect(err).To(BeNil())
+	})
+
+	AfterEach(func() {
+		s.Kill()
+		bt.cleanup()
+	})
+
+	It("Podman exec create makes an exec session", func() {
+		name := "testCtr"
+		cid, err := bt.RunTopContainer(&name, &bindings.PFalse, nil)
+		Expect(err).To(BeNil())
+
+		execConfig := new(handlers.ExecCreateConfig)
+		execConfig.Cmd = []string{"echo", "hello world"}
+
+		sessionID, err := containers.ExecCreate(bt.conn, name, execConfig)
+		Expect(err).To(BeNil())
+		Expect(sessionID).To(Not(Equal("")))
+
+		inspectOut, err := containers.ExecInspect(bt.conn, sessionID)
+		Expect(err).To(BeNil())
+		Expect(inspectOut.ContainerID).To(Equal(cid))
+		Expect(inspectOut.ProcessConfig.Entrypoint).To(Equal("echo"))
+		Expect(len(inspectOut.ProcessConfig.Arguments)).To(Equal(1))
+		Expect(inspectOut.ProcessConfig.Arguments[0]).To(Equal("hello world"))
+	})
+
+	It("Podman exec create with bad command fails", func() {
+		name := "testCtr"
+		_, err := bt.RunTopContainer(&name, &bindings.PFalse, nil)
+		Expect(err).To(BeNil())
+
+		execConfig := new(handlers.ExecCreateConfig)
+
+		_, err = containers.ExecCreate(bt.conn, name, execConfig)
+		Expect(err).To(Not(BeNil()))
+	})
+
+	It("Podman exec create with invalid container fails", func() {
+		execConfig := new(handlers.ExecCreateConfig)
+		execConfig.Cmd = []string{"echo", "hello world"}
+
+		_, err := containers.ExecCreate(bt.conn, "doesnotexist", execConfig)
+		Expect(err).To(Not(BeNil()))
+	})
+
+	It("Podman exec inspect on invalid session fails", func() {
+		_, err := containers.ExecInspect(bt.conn, "0000000000000000000000000000000000000000000000000000000000000000")
+		Expect(err).To(Not(BeNil()))
+	})
+})

pkg/bindings/test/pods_test.go

@@ -79,9 +79,7 @@ var _ = Describe("Podman pods", func() {
 
 	// The test validates the list pod endpoint with passing filters as the params.
 	It("List pods with filters", func() {
-		var (
-			newpod2 string = "newpod2"
-		)
+		newpod2 := "newpod2"
 		bt.Podcreate(&newpod2)
 		_, err = bt.RunTopContainer(nil, &bindings.PTrue, &newpod)
 		Expect(err).To(BeNil())